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Testing and analysis of the Bangladeshi Treadle pump Kroeker, Murray George 1989

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TESTING AND ANALYSIS OF THE BANGLADESHI TREADLE PUMP  By MURRAY GEORGE KROEKER B.Sc.Ag.Eng., The U n i v e r s i t y o f Manitoba, 1987  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE in THE FACULTY OF GRADUATE STUDIES (Department o f A p p l i e d S c i e n c e , C i v i l  Engineering)  We accept t h i s t h e s i s as conforming t o t h e r e q u i r e d standard  THE UNIVERSITY OF BRITISH COLUMBIA March 1989 ( c j Murray George Kroeker, 1989  In  presenting this  degree at the  thesis  in  partial  fulfilment  of  the  requirements  University  of  British  Columbia,  I agree that the  freely available for reference and study. I further agree that copying  of  department  this thesis for scholarly or  by  his  or  her  It  is  an  Library shall make it by the  understood  head of my  that  publication of this thesis for financial gain shall not be allowed without permission.  Department of  CIVIL  ENGINEERING  The University of British Columbia Vancouver, Canada  D  A  T  E  DE-6 (2/88)  APRIL  20,  19B9  advanced  permission for extensive  purposes may be granted  representatives.  for  copying  or  my written  ABSTRACT The  T r e a d l e pump was invented  workers t o p r o v i d e  i n 1980 by development  low c o s t , low t e c h n o l o g y and l o c a l l y  manufacturable i r r i g a t i o n f o r farmers i n n o r t h e r n Bangladesh.  The t w i n c y l i n d e r s t e e l - b o d i e d s u c t i o n pump,  c a l l e d t h e T r e a d l e pump, operated by a w a l k i n g motion upon two  c e n t r a l l y pivoted l e v e r s , i s well s u i t e d t o the high  water t a b l e s o f much o f Bangladesh. The extensive  i n c r e a s e d p o p u l a r i t y o f t h e pump, r e s u l t i n g from marketing e f f o r t s , w i t h annual s a l e s o f over  50,000 u n i t s i n 1987/88, has prompted s u g g e s t i o n s f o r  design  a l t e r a t i o n s , s p e c i f i c a l l y pump m a t e r i a l changes t o decrease c o s t s and i n c r e a s e s a l e s .  A t e c h n i c a l f i e l d and l a b o r a t o r y  study supported by c a l c u l a t i o n s from h y d r a u l i c t h e o r y was r e q u i r e d as a b a s i s upon which t o s t a r t d e s i g n a l t e r a t i o n s . In l a b o r a t o r y t e s t s , d i f f e r e n t pump body  configurations  were found t o have n e g l i g i b l e impact on o v e r a l l pump performance c h a r a c t e r i s t i c s . These f i n d i n g s were supported by r e s u l t s o b t a i n e d turbulent loss.  from c a l c u l a t i o n s o f f r i c t i o n and  Any worthwhile a l t e r a t i o n s must r a t h e r be  j u s t i f i e d by c o s t and manufacturing b e n e f i t s . The  combination o f computer-aided i n s t r u m e n t a t i o n and  h i g h speed data c o l l e c t i o n i n l a b o r a t o r y t e s t i n g , ii  t h e o r e t i c a l a n a l y s i s , and f i e l d t e s t i n g i n Bangladesh r e v e a l e d t h a t t h e l o s s e s i n pump performance a r e a r e s u l t o f poor v a l v e s e a l i n g , v a l v e opening and c l o s i n g d e l a y s and leakage p a s t t h e p i s t o n s e a l , r e s u l t i n g i n lower d i s c h a r g e s than had been p r e v i o u s l y assumed. irrigation  The reduced d i s c h a r g e f o r  and t h e o p e r a t o r power i n p u t l i m i t , measured a t  t h e pump, o f 55 watts r e s u l t s i n a f o u r meter maximum depth of water t a b l e t o which t h e standard 89 mm  (3.5 inch) pump  can be used, w i t h some v a r i a t i o n due t o i r r i g a t i o n requirements  and o p e r a t o r s t r e n g t h s .  Improvements t o p i s t o n v a l v e and f o o t v a l v e d e s i g n t o reduce leakage and v a l v e - d e l a y times and t h e use o f a s m a l l e r 77 mm  (3 inch) c y l i n d e r diameter,  are recommended.  a r e a c h i e v a b l e and  These improvements combine t o permit  o p e r a t i o n o f t h e pump t o n e a r l y s i x meters without  exceeding  the l i m i t o f i n p u t power o r r e d u c i n g t h e d i s c h a r g e below t h e crop i r r i g a t i o n  requirements.  TABLE OF  CONTENTS PAGE  ABSTRACT  i i  L I S T OF TABLES  v i  L I S T OF FIGURES  v i i  ACKNOWLEDGEMENT  ix  1 INTRODUCTION  1  2 BACKGROUND 2.1 TREADLE PUMP DEVELOPMENT 2.2 PREVIOUS TEST RESULTS  AND  IMPACT  3 3 8  3 DESCRIPTION OF THE TREADLE PUMP 3.1 PHYSICAL DESCRIPTION 3.2 PUMP OPERATION  14 14 19  4 PUMP OPERATION MODEL 4.1 OPERATIONAL CONSTRAINTS 4.2 CALCULATION OF UNBALANCED HEAD 4.2.1 MINOR LOSSES 4.2.2 VALVE TIMING AND LEAKAGE 4.2.3 INERTIA 4.2.4 MECHANICAL LOSSES 4.3 GOVERNING EQUATIONS  23 23 24 24 25 26 29 30  5 LABORATORY TESTING 5.1 APPARATUS DESIGN CONSIDERATIONS 5.2 TESTING PROCEDURE 5.3 DATA REDUCTION AND ANALYSIS . . . . .  35 35 39 41  6 F I E L D TESTING 6.1 APPARATUS DESIGN CONSIDERATIONS 6.2 TEST LOCATIONS AND PROCEDURE 6.3 DATA ANALYSIS  43 43 45 49  iv  V  7 RESULTS 7.1 PUMP FORCES 7.2 VALVE CLOSURE DELAYS 7.3 THE EFFECT OF WATER TABLE DEPTH ON APPLIED FORCE 7.4 THE EFFECT OF WATER TABLE DEPTH ON DISCHARGE AND VOLUMETRIC EFFICIENCY 7.5 POWER INPUT REQUIREMENTS 7.6 THE EFFECT OF PUMP AGE ON DISCHARGE AND VOLUMETRIC EFFICIENCY 7.7 THE EFFECT OF PUMP BODY CONFIGURATION ON VOLUMETRIC EFFICIENCY, POWER REQUIREMENTS AND DISCHARGES  51 51 56 60  8 DISCUSSION 8.1 VALIDATION OF THEORETICAL MODEL BY LABORATORY TESTS 8.2 COMPARISON OF LABORATORY AND FIELD TEST RESULTS 8.3 IMPLICATIONS OF THE RESULTS ON PUMP RE-DESIGN .  71 71 72 74  9 CONCLUSION  79  LIST OF REFERENCES  82  APPENDIX 1: AVERAGED LABORATORY TEST DATA  85  APPENDIX 2: AVERAGED FIELD TEST DATA  86  60 63 67 68  LIST OF TABLES T a b l e I : T r e a d l e pump s a l e s o f I n t e r n a t i o n a l Development E n t e r p r i s e s (IDE), Rangpur D i n a j p u r R e h a b i l i t a t i o n S e r v i c e (RDRS) and o t h e r s . (Source: IDE 1988) 7 T a b l e I I : Percent  l o s s from p i s t o n and  vi  f o o t v a l v e d e l a y s . 57  LIST OF FIGURES F i g u r e 1: G e o g r a p h i c a l  l o c a t i o n o f Bangladesh  5  F i g u r e 2: Water t a b l e depths i n Bangladesh  6  F i g u r e 3: Rope and p u l l e y type T r e a d l e o p e r a t i o n  8  F i g u r e 4: C e n t r a l l y p i v o t e d "dheki" type T r e a d l e  operation.9  F i g u r e 5: "Dheki" s t y l e f i e l d pump  i n s t a l l a t i o n of the Treadle  F i g u r e 6: The two p i s t o n c o n f i g u r a t i o n s , t h e two-plate d e s i g n and t h e No. 6 s t y l e p i s t o n , and t h e two types of junctions tested  15  16  F i g u r e 7: F i e l d o p e r a t i o n o f T r e a d l e pump i n Bangladesh  18  F i g u r e 8: The pump c y c l e d e f i n e d by v a l v e p o s i t i o n s . F i g u r e 9:  .  19  C h a r a c t e r i s t i c p i s t o n motion parameters. . .  27  F i g u r e 10: An example o f c a l c u l a t e d f o r c e r e s u l t s  with  l a b o r a t o r y measured parameters F i g u r e 11: Instrumentation F i g u r e 12: Laboratory  34  f o r t h e l a b o r a t o r y t e s t s . . . 36  apparatus  38  F i g u r e 13: L o c a t i o n o f f i e l d t e s t s .  46  F i g u r e 14: Force-displacement type p i s t o n s F i g u r e 15: Force-displacement  52  loop u s i n g t h e two-plate loop u s i n g t h e No. 6 type  piston  53  F i g u r e 16: V a r i a t i o n s i n f o r c e w i t h water t a b l e depth.  61  F i g u r e 17: The e f f e c t o f water t a b l e depth on v o l u m e t r i c efficiency  62  vii  viii F i g u r e 18: Laboratory requirements  and estimated  f i e l d power i n p u t 65  F i g u r e 19: E f f e c t o f pump age on v o l u m e t r i c and d i s c h a r g e from f i e l d t e s t s  efficiency 67  F i g u r e 20: E f f e c t o f pump c o n f i g u r a t i o n on l a b o r a t o r y measured v o l u m e t r i c e f f i c i e n c y and d i s c h a r g e . . . .  69  F i g u r e 21: Comparison results  71  of calculated  and l a b o r a t o r y  ACKNOWLEDGEMENT I g r a t e f u l l y acknowledge t h e Canadian I n t e r n a t i o n a l Development Agency  (CIDA) f o r f i n a n c i a l support through t h e  Awards f o r Canadians Program.  I a l s o would l i k e t o  acknowledge Bob Nanes and t h e r e s t o f t h e s t a f f o f I n t e r n a t i o n a l Development E n t e r p r i s e s and  the United  States  i n Bangladesh, Canada  f o r t h e i r assistance,  valuable  i n s i g h t s and l o g i s t i c a l support, Dr. Stephen V. A l l i s o n , previously  D i r e c t o r o f O p e r a t i o n s f o r IDE and c u r r e n t l y  consultant  f o r t h e World Bank, f o r h i s guidance and h e l p as  program s u p e r v i s o r Engineering  and Dr. M. C. Quick o f t h e C i v i l  department a t t h e U n i v e r s i t y o f B r i t i s h Columbia  f o r h i s support i n a r r a n g i n g and  laboratory  f o r h i s i n t e r e s t i n the p r o j e c t .  ix  space and equipment  1 INTRODUCTION T h i s t h e s i s examines t h e performance o f two c o n f i g u r a t i o n s o f s t e e l T r e a d l e pump b o d i e s and p i s t o n configurations, use  i n c l u d i n g t h e d e s i g n s c u r r e n t l y marketed f o r  i n Bangladesh.  I n v e s t i g a t i o n o f t h e pumps by i n t e n s i v e  l a b o r a t o r y t e s t i n g and data a n a l y s i s , f i e l d t e s t s , and a n a l y s i s from h y d r a u l i c theory p r o v i d e s e v a l u a t i n g t h e pump d e s i g n An  initial  a basis f o r  and a l t e r a t i o n a l t e r n a t i v e s .  study o f t h e pump uses, proposed  design  a l t e r a t i o n s and pump theory was conducted i n Bangladesh d u r i n g t h e summer o f 1987, f o l l o w e d by l a b o r a t o r y t e s t i n g o f a l t e r n a t e pump and p i s t o n d e s i g n s a t t h e U n i v e r s i t y o f B r i t i s h Columbia a t Vancouver, Canada, i n mid-1988.  Field  t e s t i n g o f T r e a d l e pumps, u s i n g t h e c u r r e n t l y marketed c o n f i g u r a t i o n o f pump body and p i s t o n s , was conducted i n t h e c e n t r a l , eastern  and n o r t h e r n  regions  o f Bangladesh a t t h e  s t a r t o f i r r i g a t i o n f o r t h e 1988-89 d r y season crops i n l a t e November and December 1988. Included  i s a h i s t o r y and d e s c r i p t i o n o f t h e T r e a d l e  pump, t o f a m i l i a r i z e r e a d e r s w i t h t h i s technology, and an examination o f t h e pump h y d r a u l i c s t o d e s c r i b e t h e pump operation  i n more d e t a i l and p r o v i d e 1  the basis f o r the  2  analysis of laboratory laboratory  and f i e l d t e s t s .  Adescription  and f i e l d t e s t s and t h e p r e s e n t a t i o n  of the  of the test  r e s u l t s , as w e l l as those from t h e t h e o r y based c a l c u l a t i o n s , p r o v i d e s a comprehensive view o f t h e pump performance c h a r a c t e r i s t i c s .  The r e s u l t s a l s o i d e n t i f y t h e  mechanisms a f f e c t i n g pump performance as w e l l as p r o v i d i n g the b a s i s f o r proposed d e s i g n a l t e r a t i o n s . The  t e s t i n g and study i n c l u d e d  pump d e s i g n s and o p e r a t i o n s e c t i o n two.  i s based on t h e T r e a d l e  configuration  T h i s uses c e n t r a l l y p i v o t e d  described i n l e v e r s t o operate  the pump, r e f e r r e d t o as t h e " d h e k i " o p e r a t i o n  s t r u c t u r e , as  i s p r i m a r i l y used i n Bangladesh a t t h i s time.  The t e s t i n g  parameters and d e s i g n a l t e r n a t i v e s examined a r e l i m i t e d t o those manufacturable w i t h m a t e r i a l s in  Bangladesh.  and t e c h n o l o g y a v a i l a b l e  2 BACKGROUND 2.1 TREADLE PUMP DEVELOPMENT AND The T r e a d l e pump was  IMPACT  i n v e n t e d i n 1980 by Gunnar Barnes  and Dan J e n k i n s , development workers w i t h the nongovernmental o r g a n i z a t i o n s Rehabilitation Service  (NGOs), t h e Rangpur-Dinajpur  (RDRS) and USAid  o p e r a t i n g i n n o r t h e r n Bangladesh  respectively,  (RDRS 1984).  Bangladesh, l o c a t e d e a s t o f I n d i a and north-west o f Burma, encompassing  the Ganges and Brahmaputra  r i v e r deltas  where they e n t e r the Bay o f Bengal, i l l u s t r a t e d i n f i g u r e 1, i s w e l l s u i t e d t o human powered i r r i g a t i o n because: a)  Labor i s w i d e l y a v a i l a b l e , e i t h e r by t h e pump owner  o r a t low c o s t . b)  The h i g h water t a b l e throughout most o f t h e c o u n t r y  i s w i t h i n t h e 10 meter l i m i t o f s u c t i o n pumps, as shown i n the water t a b l e depth map c)  i n f i g u r e 2 and,  farm p l o t s are t y p i c a l l y so s m a l l t h a t t h e q u a n t i t i e s  o f water r e q u i r e d d a i l y a r e w i t h i n t h e l i f t i n g c a p a c i t y o f a s i n g l e human o p e r a t o r . The s i z e o f p l o t s i r r i g a t e d by manual i r r i g a t i o n range i n s i z e from 0.25  t o 1 h e c t a r e (Orr and Islam 1988).  High  v a l u e c r o p s such as v e g e t a b l e s , s p i c e s and tobacco are grown as t h e y g e n e r a l l y have lower i r r i g a t i o n requirements, l e s s 3  4 than 6 mm/day on average greater f i n a n c i a l parameters, to  (EPC 1988 T a b l e s 24-26), and  r e t u r n than r i c e c r o p s .  Given  t h e i r r i g a t i o n water requirements  these  v a r y from 15  60 c u b i c meters p e r day f o r 0.25 and 1 h e c t a r e  area r e s p e c t i v e l y .  I n more understandable  terms f o r t h e  p h y s i c a l e f f o r t needed t o meet t h e s e requirements manual i r r i g a t i o n , t h i s equates t o l i f t i n g  irrigated  using  from 15 t o 60  tonnes o f water a v e r t i c a l d i s t a n c e o f up t o f o u r meters every day d u r i n g p e r i o d s o f peak i r r i g a t i o n The o r i g i n a l  requirements.  aim i n d e s i g n i n g t h e pump was t o p r o v i d e low  c o s t manual i r r i g a t i o n , t o b e n e f i t low income farmers i n t h e Rangpur and D i n a j p u r r e g i o n s o f n o r t h e r n Bangladesh.  Since  i t s i n t r o d u c t i o n , use o f t h e pump has spread t o many o t h e r new r e g i o n s o f Bangladesh p r e v i o u s l y without irrigated  i r r i g a t i o n or  by more expensive o r l e s s a p p r o p r i a t e means.  r e c e n t socio-economic c o s t o f 1488 t a k a  In a  study o f t h e t r e a d l e pump, t h e low  ($60 CAD) (EPC 1988, t a b l e 29),  including  i n s t a l l a t i o n on an u n p l a s t i c i z e d P o l y v i n y l C h l o r i d e (uPVC) t u b e w e l l , was found t o p r o v i d e 100% investment season w i t h a minimum i r r i g a t e d acres)  r e t u r n i n one  area o f 0.08 h e c t a r e s (.16  (Orr and Islam 1988), p r o v i n g t h a t t h e aim o f t h e  original  d e s i g n has been a c h i e v e d .  B e n e f i t s o f T r e a d l e pump i r r i g a t i o n i n c l u d e d r y season c r o p p i n g , p r e v i o u s l y not p o s s i b l e f o r l a c k o f i r r i g a t i o n , diversification  o f crops t o modern h i g h y i e l d r i c e  varieties  5 and v e g e t a b l e s , job c r e a t i o n , w i t h 30% o f pumping labour b e i n g h i r e d , and i n c r e a s e d s e l f s u f f i c i e n c y i n r i c e Islam 1988).  F i g u r e 1: Geographical l o c a t i o n of  Bangladesh.  (Orr and  F i g u r e 2: Water t a b l e depths i n Bangladesh. (Source: U n i t e d Nations 1982, P l a t e 7)  7 S a l e s o f t h e T r e a d l e pump have i n c r e a s e d d r a m a t i c a l l y i n the p a s t  f o u r years  as i s shown i n t a b l e 1.  YEAR  IDE  RDRS  OTHERS  TOTAL  1980-85 1985- 86 1986- 87 1987- 88  0 120 12,000 12,000  39,870 10,316 3,000 3,000  0 4,000 16,000 27,000  39,870 14,436 30,000 43,938  T a b l e I : T r e a d l e pump s a l e s o f I n t e r n a t i o n a l Development E n t e r p r i s e s (IDE), Rangpur D i n a j p u r R e h a b i l i t a t i o n S e r v i c e (RDRS) and o t h e r s . (Source: IDE 1988)  The  l a r g e and i n c r e a s i n g s a l e s o f t h e T r e a d l e pump a r e  a t t r i b u t a b l e t o t h e low i n i t i a l  c o s t , t h e ease o f  maintenance and r e p a i r , comfort o f o p e r a t i o n , t h e a v a i l a b i l i t y o f replacement p a r t s and t h e a b i l i t y t o make some r e p a i r s u s i n g salvaged Although i n i t i a l l y  p a r t s such as i n n e r tube rubber.  installed  on bamboo t u b e w e l l s , t h e  i n c r e a s e d a v a i l a b i l i t y and i n c r e a s e d market demand f o r uPVC p i p e has r e s u l t e d i n i n c r e a s i n g uPVC usage f o r manual pump tubewells. and  T h i s has r e s u l t e d i n more c o n s i s t e n t w e l l  life  i n c r e a s e d b e n e f i t s but a t an i n c r e a s e i n c o s t and a  g r e a t e r dependence upon imported m a t e r i a l s .  In a d d i t i o n t o  the obvious b e n e f i t s o f t h e pump, i n c r e a s i n g l y focused marketing e f f o r t s throughout Bangladesh by v a r i o u s NonGovernmental O r g a n i z a t i o n s  (NGO's) and Bangladeshi p r i v a t e  businessmen have c o n t r i b u t e d g r e a t l y t o t h e a v a i l a b i l i t y and  8 q u a l i t y of the pumps s o l d , and have f u r t h e r i n c r e a s e d  2.2  sales.  PREVIOUS TEST RESULTS The i n c r e a s e i n p o p u l a r i t y of manual i r r i g a t i o n i n  Bangladesh and the concern with d r i n k i n g water supply worldwide, brought on i n p a r t by the U n i t e d Nations d e c l a r e d Decade o f S a n i t a t i o n and Water Supply i n 1980, i n i n c r e a s e d t e s t i n g and documentation throughout the world.  has r e s u l t e d  o f pump performance  Although the primary focus has been  on d r i n k i n g water pumps, manual i r r i g a t i o n pumps, such as the  T r e a d l e , Rower and No.  6 pumps used i n Bangladesh, have  r e c e i v e d a t t e n t i o n from r e g i o n a l NGOs, farmers and s m a l l business i n t e r e s t s .  F i g u r e 3: Rope and p u l l e y type T r e a d l e o p e r a t i o n . (Source: Barnes 1985)  F i g u r e 4: C e n t r a l l y p i v o t e d "dheki" type T r e a d l e o p e r a t i o n . (Source: S t i c k n e y , R.E., e t a l . 1987)  Over t h e p a s t f o u r years, t h e T r e a d l e pump has been t e s t e d by RDRS, t h e Mennonite C e n t r a l Committee (MCC), t h e I n t e r n a t i o n a l R i c e Research I n s t i t u t e  (IRRI), t h e Bangladesh  U n i v e r s i t y o f E n g i n e e r i n g and Technology (BUET), and most r e c e n t l y by E n g i n e e r i n g and Planning Consultants L i m i t e d o f Dhaka, Bangladesh  (EPC) on c o n t r a c t w i t h t h e Bangladesh  R u r a l Development  Board (BRDB) and t h e World Bank.  The f i v e t e s t s have v a r i e d i n focus as f o l l o w s :  10 1) The RDRS t e s t s d e a l t w i t h depth t o water t a b l e t o d i s c h a r g e r e l a t i o n s h i p of the o r i g i n a l pump d e s i g n  and  l a r g e r p i s t o n diameter p r o t o t y p e s f o r use a t s h a l l o w e r depths (RDRS 1983). 2) The MCC  t e s t s focused on the impact  of pump i n s t a l l a t i o n  parameters, such as t u b e w e l l l e n g t h , diameter l e n g t h , on the Rower, T r e a d l e and No.  and  filter  6 pumps from a  p r i m a r i l y s t a t i s t i c a l a n a l y s i s of a s m a l l s i z e t e s t sample (Spare and P r i t c h a r d 1981). 3) The  IRRI t e s t s focused on the a d a p t a t i o n and  promotion o f the T r e a d l e pump i n the  initial  Philippines.  Comparisons o f the power i n p u t requirements  f o r the rope and  p u l l e y and the c e n t r a l l y p i v o t e d "dheki" s t y l e s o f T r e a d l e pump i n s t a l l a t i o n s , shown i n f i g u r e s 3 and 4, i n d i c a t e d  no  s i g n i f i c a n t d i f f e r e n c e s between them ( S t i c k n e y e t a l . 1987). The  " d h e k i " s t y l e o p e r a t i o n was,  however, found t o more  c o m f o r t a b l e t o operate, which i s a l s o the reason f o r the l a r g e i n c r e a s e i n " d h e k i " s t y l e i n s t a l l a t i o n s over rope and p u l l e y s t y l e i n s t a l l a t i o n s i n Bangladesh. 4) The  BUET t e s t s c o n c e n t r a t e d on the r e l a t i o n of power  e f f i c i e n c y and d i s c h a r g e t o o p e r a t o r c h a r a c t e r i s t i c s  (Bureau  of  of  Research T e s t i n g and C o n s u l t a t i o n . 1986).  h i r e d urban o p e r a t o r s  (rickshaw operators)  t e s t s , the l a c k o f comparable f i e l d  The use  i n the l a b o r a t o r y  t e s t s , the use  of  observational recording of force transducer readings to c a l c u l a t e power i n p u t a t the pump, and the l a c k o f  11 t h e o r e t i c a l a n a l y s i s t o support reduced c o n f i d e n c e  t h e l a b o r a t o r y data, a l l  i n the report's  5) The EPC r e p o r t focused  conclusions.  on t h e f i e l d performance o f t h e  T r e a d l e , Rower and No.6 pumps. The t e s t s were commissioned to provide a basis f o r planning  o f i r r i g a t i o n pump promotion  as p a r t o f o v e r a l l a g r i c u l t u r a l development p l a n n i n g 1988) f o r t h e BRDB and the World Bank.  (EPC  The pumps were f i e l d  t e s t e d f o r two months, a t f o u r l o c a t i o n s , t o compare t h e discharge,  pump wear and o p e r a t o r  each pump type.  The f i n a l  input c h a r a c t e r i s t i c s of  r e p o r t concluded t h a t t h e T r e a d l e  pump be recommended f o r manual i r r i g a t i o n i n s t a l l a t i o n s on the grounds o f lowest c o s t , ease o f r e p a i r and l a r g e discharge  f o r a g i v e n amount o f o p e r a t o r  p a r t i c u l a r i n t e r e s t are the discharge  power.  Of  r e s u l t s , w i t h an  average o f 4 3 l i t r e s p e r minute a t a water t a b l e depth o f 3.3 6 meters.  T h i s i s achieved  w i t h a maximum power i n p u t o f  69.73 watts over a 20 minute p e r i o d o r 51.6 watts over 30 minutes o f s u s t a i n e d pumping. estimated  from t h e o p e r a t o r metabolism parameter o f body  s u r f a c e area The  (EPC 1988, Table  discharge  by BUET.  The power i n p u t v a l u e s were  12, s e c . 3.18).  r e s u l t s were much l e s s than those  presented  The two r e p o r t s r e p o r t s i m i l a r power i n p u t  measurements but t h e r e s u l t s a r e not comparable.  The EPC  r e s u l t s were based on t h e measurement o f t h e m e t a b o l i c of the operator,  rate  which would g i v e t h e power i n p u t t o t h e  t r e a d l e l e v e r s (EPC 1988, s e c . 3.18) w h i l e t h e BUET t e s t s  12 measured t h e average f o r c e i n p u t t o t h e p i s t o n r o d g i v i n g the power i n p u t t o t h e pump (Bureau o f Research T e s t i n g and C o n s u l t a t i o n , sec. 3.3).  The power a t t h e o p e r a t o r  and a t  the pump can n o t be equal due t o f r i c t i o n l o s s e s between t h e t r e a d l e l e v e r s , a x l e p i n and between t h e rope and p u l l e y system used w i t h these t e s t s , as w e l l as unmonitored metabolic  losses.  Given t h e d i f f e r e n c e s between t h e  d i s c h a r g e measurements, power i n p u t r e s u l t s , t h e more r e p r e s e n t a t i v e f i e l d t e s t c o n d i t i o n s and t h e l a r g e number o f t e s t s , t h e EPC r e p o r t seems t o p r o v i d e a more complete i n d i c a t i o n o f f i e l d T r e a d l e pump performance. A l l o f t h e T r e a d l e pump t e s t s t o date used t h e o r i g i n a l d e s i g n r o p e - p u l l e y s t y l e t r e a d l e l e v e r c o n f i g u r a t i o n , shown i n f i g u r e 3, as opposed t o t h e c e n t r a l l y p i v o t e d  "dheki"  s t y l e c o n f i g u r a t i o n used on most i n s t a l l a t i o n s s i n c e 1986, shown i n f i g u r e s 3,4 and 6. The  " d h e k i " s t y l e o p e r a t i o n has been adopted by t h e  B a n g l a d e s h i farmer i n an e f f o r t t o reduce t h e number o f moving p a r t s s u b j e c t e d  t o wear and r e q u i r i n g p e r i o d i c  replacement and t o i n c r e a s e o p e r a t o r  comfort.  Unfortunately,  the s h o r t e r s t r o k e l e n g t h s o f t h e "dheki" s t y l e r e s u l t s i n lower d i s c h a r g e comfort.  and g r e a t e r l o s s e s w i t h t h e i n c r e a s e s i n  The i n c r e a s e i n o p e r a t o r  o p e r a t i o n has been obtained  comfort and ease o f  from t h e change o f pumping s t y l e  t o a s h i f t i n g o f body weight from s i d e t o s i d e , p i v o t i n g a t the h i p s and without bending t h e knees, from t h e t h e l o n g e r  13 bent-knee  s t e p - l i k e o p e r a t i o n o f rope and p u l l e y s t y l e .  The  large p o p u l a r i t y of the "dheki" s t y l e operation c l e a r l y i l l u s t r a t e s t h e g r e a t e r importance o f comfort and ease o f o p e r a t i o n t o t h e Bangladeshi pump o p e r a t o r compared t o t h e mechanical e f f i c i e n c y o f t h e pump mechanism.  This p r i o r i t y  o f o p e r a t o r comfort over mechanical e f f i c i e n c y i n t h e case o f t h e o p e r a t i o n c o n f i g u r a t i o n , c l e a r l y shows t h a t c h a r a t e r i s t i c s o f t h e T r e a d l e pump t h a t must be c a r e f u l l y c o n s i d e r e d i n any d e s i g n a l t e r a t i o n s extend beyond t h e p u r e l y t e c h n i c a l performance  characteristics.  The lower d i s c h a r g e d a t a g i v e n i n t h e EPC r e p o r t i s c o n t r a r y t o p r e v i o u s pump performance  assumptions.  The l a c k  o f agreement between t h e o r e t i c a l a n a l y s i s , l a b o r a t o r y and f i e l d t e s t r e s u l t s i n a l l o f t h e above r e p o r t s p r e c l u d e s t h e i r use as a b a s i s f o r d e s i g n improvements and comparisons o f a l t e r n a t i v e pump d e s i g n s . The need f o r f u r t h e r t e c h n i c a l knowledge was i d e n t i f i e d i n 1988 by t h e MPG, an o r g a n i z a t i o n comprised o f manufacturers and marketers o f manual i r r i g a t i o n pumps i n Bangladesh.  3 DESCRIPTION OF THE TREADLE PUMP 3.1  PHYSICAL DESCRIPTION The  T r e a d l e pump i s a two c y l i n d e r manual s u c t i o n pump  constructed  from sheet s t e e l .  s i n g l e 40 mm  I t i s t y p i c a l l y mounted on a  (1.5 inch) diameter t u b e w e l l , a l s o r e f e r r e d t o  as t h e r i s i n g main o r r i s e r .  A t t a c h e d t o t h e bottom o f t h e  r i s i n g main i s a s l o t t e d u n p l a s t i c i z e d  polyvinyl-chloride  (uPVC) o r p o l y - p r o p y l e n e c l o t h covered s l o t t e d bamboo screen l o c a t e d below t h e water t a b l e , as shown i n f i g u r e 5. The  pump body c o n s i s t s o f two p a r a l l e l s t e e l c y l i n d e r s  made from r o l l e d and welded sheet a t t a c h e d t o t h e t o p o f a Y o r box shaped j u n c t i o n .  A s h o r t s t e e l 40 mm  (1.5 inch) p i p e  i s welded t o t h e bottom o f t h e j u n c t i o n t o connect t h e pump t o t h e uPVC o r bamboo t u b e w e l l . P l a s t i c t u b e w e l l components predominate i n t h e more recent  pump i n s t a l l a t i o n s i n most o f Bangladesh due t o t h e  superior  d u r a b i l i t y and s e a l i n g o f t h e r i s e r , a l t h o u g h t h e  c o s t o f t h e p l a s t i c components a r e g r e a t e r  than t h e bamboo  components. Two d e s i g n s o f p i s t o n were t e s t e d : (a) The o r i g i n a l two-plate p i s t o n d e s i g n which c o n s i s t s o f a perforated  p l a t e mounted on a s t e e l pump r o d above a s o l i d  plate with a p l a s t i c i z e d p o l y - v i n y l chloride 14  (pPVC) cup s e a l  15  -  PUMP >  SUPERSTRUCTURE  HAND  HOLD  AXLE  PIN  CCENTRAL  TREADLE  TREADLE  TUBEWELL  CASING  CBAMBOCQ  OR  PIVOT^  LEVERS  RISING  CBAMBOCO  MAIN  CuPVC}  PUMP BODY  S I LT  V —  FINE  WATER 1 . •  TABLE -  -4 . o  meter  SAND  COURSE  SAND  7.0  -  2 0 . •  meters  SCREEN  F i g u r e 5: "Dheki" s t y l e f i e l d T r e a d l e pump.  i n s t a l l a t i o n o f the  p l a c e d between them and, (b) t h e No. 6 p i s t o n , adapted f o r use i n t h e T r e a d l e pump. The No. 6 p i s t o n c o n s i s t s o f a molded uPVC poppet  valve,  used w i t h t h e same type o f pPVC cup s e a l as used i n t h e two p l a t e design, attached plate.  sandwiched between a threaded upper  cage,  t o t h e pump r o d , and a s i m i l a r l y t h r e a d e d lower The poppet v a l v e ,  as shown i n f i g u r e 6.  s e a l and v a l v e seat a r e c o n f i g u r e d  I t i s c a l l e d t h e No.6 p i s t o n  because  o f i t s use i n t h e w i d e l y used c a s t i r o n Number 6 d r i n k i n g water pump, which i s s i m i l a r t o t h e hand pump s t i l l  used f o r  most manual pump a p p l i c a t i o n s i n North America.  STANDARD CONFIGURATI ON  F i g u r e 6: The two p i s t o n c o n f i g u r a t i o n s ,  t h e two-plate  d e s i g n and t h e No. 6 s t y l e p i s t o n , and t h e two t y p e s o f junctions.  17 Both p i s t o n types a r e connected t o t h e h o r i z o n t a l bamboo rods, c a l l e d t r e a d l e s , by a hook and p i n arrangement a t t h e top o f t h e p i s t o n The  rod.  lower v a l v e s ,  or foot valves,  c o n s i s t o f weighted  i n n e r - t u b e rubber f l a p s mounted a t t h e base o f t h e c y l i n d e r s , where t h e c y l i n d e r s j o i n t o t h e s m a l l e r j u n c t i o n box.  diameter  Connection o f t h e f l a p t o t h e pump body i s by  nuts and b o l t s t o t h e c y l i n d e r base p l a t e . The  box shaped j u n c t i o n and t h e two-plate p i s t o n d e s i g n  are t h e s t a n d a r d c o n f i g u r a t i o n used i n Bangladesh due t o t h e low  c o s t and ease o f manufacture. As  shown i n f i g u r e 7, t h e pump i s operated by t h e  t r e a d i n g a c t i o n o f t h e o p e r a t o r on t h e o p p o s i t e c e n t r a l p i v o t from t h e pump.  The energy e x e r t e d  side of the by t h e  o p e r a t o r i s used i n t h r e e ways, t o pump water, t o overcome friction  a t t h e c e n t r a l p i v o t and t h e p i s t o n r o d  c o n n e c t i o n s , and t o i n c r e a s e t h e p o t e n t i a l energy o f t h e t r e a d l e l e v e r s by l i f t i n g t h e t r e a d l e mass on t h e pump s i d e o f t h e p i v o t n o t balanced by t h e mass on t h e o p e r a t o r s i d e . T h i s d i f f e r e n c e i n t r e a d l e mass on t h e pump s i d e o f t h e c e n t r a l p i v o t i s termed t h e unbalanced t r e a d l e mass. pump i s p r o p e r l y  s e t up, t h e energy used t o r a i s e t h e  t r e a d l e l e v e r w i l l be equal t h e energy r e q u i r e d downward s t r o k e  I f the  for the  o f t h e p i s t o n and minimal energy i s wasted.  In a c t u a l p r a c t i c e , many o f t h e pumps a r e i n s t a l l e d w i t h increased  unbalanced t r e a d l e mass t o i n c r e a s e t h e upward  18 pressure the  on t h e o p e r a t o r ' s  piston.  action  increases operator  the return stroke of  c o n t r o l over the loose  o f t h e l e v e r and i n c r e a s e s t h e speed o f t h e r e t u r n  stroke. the  This  foot during  I n extreme cases,  t h e l e v e r s may b e s e t up s o t h a t  end o f t h e l e v e r s on t h e o p e r a t o r ' s  pivot  touch  stroke results  side of the central  t h e ground a t t h e lower end o f t h e o p e r a t o r  a n d h i t t h e pump a t t h e upward e n d . i n wasted energy as a r e s u l t  Although  of hitting  this  t h e pump a n d  g r o u n d a n d a l s o i n c r e a s e s wear on t h e t r e a d l e l e v e r s , p i v o t s and  t h e pump body r e s u l t i n g  benifit  that  i t decreases the s e n s i t i v i t y  of the operator levers  simplicity  over e f f i c i e n c y The  smooth o p e r a t i o n .  of operation  and smoothness w i t h  pump c a n a l s o b e o p e r a t e d  each s i d e o f t h e s u p e r s t r u c t u r e ,  can take some  using  i t has t h e  and s k i l l  t o obtain the correct balance  a n d t h e more o p t i m a l  that greater  i n rough o p e r a t i o n ,  required  i n the treadle This  shows  precedence  operators.  two o p e r a t o r s ,  but this  one o n  i s n o t common  practice.  F i g u r e 7: F i e l d o p e r a t i o n (Photo by Author)  of the Treadle  pump i n B a n g l a d e s h .  19 3.2 PUMP OPERATION There a r e f o u r d i s t i n c t stages i n t h e s t r o k e c y c l e o f t h e Treadle  pump, which c o n s i s t s o f a s i n g l e up and down  stroke  c y c l e i n both c y l i n d e r s , w i t h a h a l f c y c l e phase d i f f e r e n c e between c y l i n d e r s .  The stage o f t h e c y c l e can be d e f i n e d by  the p o s i t i o n and d i r e c t i o n o f movement o f t h e p i s t o n a t any p o i n t i n time.  The f o u r stages,  f o r one c y l i n d e r i n t h e  pump c y c l e u s i n g t h e two-plate p i s t o n , i s shown i n f i g u r e 8.  S T A G E  1  S T A G E  2  S T A G E  3  F i g u r e 8: The pump c y c l e d e f i n e d by v a l v e In t h e f i r s t  S T A G E  A  positions.  stage, o c c u r r i n g w i t h t h e i n i t i a l  upward  movement o f t h e p i s t o n from t h e lowered p o s i t i o n , t h e p i s t o n v a l v e c l o s e s w i t h t h e upward movement o f t h e p i s t o n p l a t e t o connect w i t h t h e pPVC cup s e a l .  When no water i s l i f t e d  above t h e p i s t o n by t h e p i s t o n movement, o n l y t h e f r i c t i o n  20 force of the drag  cup  s e a l moving a g a i n s t  f o r c e of the  exerted very  on  the  p i s t o n m o v i n g upward t h r o u g h t h e  piston.  The  second stage,  decrease i n pressure lifting  power i n p u t  immediately below the  o f w a t e r above t h e  combination of the  p i s t o n to the  low  positive differential  water t a b l e through the The  initial  causes the duration the  low  piston  foot valve  seal  stage  are  is  and  force  stroke  the  from above the  beginning of t h i s stroke.  The  piston  and  piston  toward the  stage.  and  and  the  to  drag  The  to  piston  are  piston  mass a c c e l e r a t e d  of the  with the  stroke  the to  to  discharge of the  the  required  equal  the  discharge  the  towards the  the  the  constant  is a result  and  produce  force through  water column a c c e l e r a t i o n w i t h the top  valve,  overcome b o t h  a t a maximum a t  in force  the  cylinder.  water t o the  stage with a reduction reduction  i n t o the  additional force  the  and  flow from  r i s i n g main t o  lift  spout.  results in a  i s required  remains c l o s e  water i n the  piston  Force  a the  piston  remain open f o r  piston  f o r c e and  motion of the spout  upward s t r o k e .  this  causing  c l o s i n g of the  t o open and  and  discharge  water t a b l e  r i s i n g m a i n and  friction  accelerate  the  pressure,  p r e s s u r e below the  throughout t h i s  the  water  piston  p r e s s u r e below the  flow, with the  of the  foot-valve,  to  in this  the  f u r t h e r upward movement c a u s e s  a t m o s p h e r i c p r e s s u r e a c t i n g on net  c y l i n d e r and  small.  In the  The  the  of  top  of  reduced  slowing of  reduction water from  of  the the  above  the p i s t o n .  An a d d i t i o n a l f o r c e i s r e q u i r e d  i n t h i s stage  t o a c c e l e r a t e and l i f t t h e unbalanced mass o f t h e t r e a d l e l e v e r , used as t h e a c t u a t i n g the r e t u r n s t r o k e .  f o r c e i n stages t h r e e  and four,  The magnitude o f t h i s f o r c e depends on  the p o s i t i o n o f t h e c e n t r a l p i v o t on t h e t r e a d l e l e v e r s . The  degree o f unbalance r e s u l t s from t h e q u a l i t y o f  i n s t a l l a t i o n and, i d e a l l y , should n e a r l y equal t h e f o r c e r e q u i r e d t o move t h e p i s t o n downward d u r i n g stroke.  the return  The major p o r t i o n o f work and t h e maximum power i s  imparted t o t h e pump i n t h i s stage. In stage t h r e e ,  t h e downward r e t u r n s t r o k e b e g i n s w i t h  the opening o f t h e p i s t o n v a l v e . the v a l v e  The upwards movement o f  i s l i m i t e d by t h e upper p e r f o r a t e d  r e s u l t s i n a d i f f e r e n t i a l pressure across  plate.  This  t h e p i s t o n and  f o r c e s water t o flow through t h e p e r f o r a t e d  p l a t e and t h e  annulus between t h e lower p l a t e and t h e c y l i n d e r w a l l previously  s e a l e d by t h e pPVC cup s e a l .  The downward  movement o f t h e water i n t h e c y l i n d e r caused by t h e increased  p r e s s u r e causes t h e f o o t v a l v e t o c l o s e ,  the r e v e r s e main.  stopping  flow o f water from t h e c y l i n d e r i n t o t h e r i s i n g  Only t h e f r i c t i o n f o r c e o f t h e cup s e a l r e s u l t i n g  from t h e p i s t o n motion, t h e drag f o r c e o f t h e water through the p i s t o n , and t h e i n i t i a l drag f o r c e through t h e f o o t valve,  need t o be overcome d u r i n g t h i s stage.  The f o r c e f o r  the downward movement o f t h e p i s t o n i n stages t h r e e and f o u r  i s p r o v i d e d by t h e unbalanced mass o f t h e t r e a d l e  lever  which was r a i s e d i n stages one and two. In stage f o u r , t h e p i s t o n r e t u r n s t o t h e bottom o f t h e stroke,  i n h i b i t e d o n l y by t h e r e s i s t a n c e  o f flow through t h e  p i s t o n v a l v e and t h e f r i c t i o n o f t h e cup s e a l a g a i n s t t h e c y l i n d e r w a l l . Some water i s d i s c h a r g e d by displacement from the p i s t o n and p i s t o n r o d . The but  second c y l i n d e r f o l l o w s  t h e same c y c l e as t h e f i r s t ,  i s o f f s e t one h a l f c y c l e , r e s u l t i n g i n a continuous flow  of water from t h e pump.  4 PUMP OPERATION MODEL 4.1 OPERATIONAL CONSTRAINTS As b r i e f l y d e s c r i b e d i n s e c t i o n t h r e e , t h e o p e r a t i o n o f the  T r e a d l e pump u t i l i z e s t h e d i f f e r e n c e between atmospheric  p r e s s u r e , and t h e low p r e s s u r e c r e a t e d below t h e p i s t o n t o p r o v i d e flow from t h e water t a b l e t o t h e pump. p r e s s u r e , a t 20 degrees C e l s i u s , i s 101 kPa.  Atmospheric  When expressed  i n h e i g h t o f water over a u n i t area, termed atmospheric head, i s e q u a l t o 10.23 meters.  The p r e s s u r e d i f f e r e n t i a l  between atmospheric and t h a t produced below t h e p i s t o n i s termed unbalanced head  (UH). I d e a l l y , when t h e depth t o t h e  water t a b l e e q u a l s atmospheric head, t h e unbalanced head and resulting l i f t i n g  f o r c e a r e reduced t o z e r o .  This results  i n t h e t h e o r e t i c a l maximum h e i g h t f o r t h e o p e r a t i o n o f t h e T r e a d l e pump b e i n g c o n s t r a i n e d t o t h e 10.23 meter l i m i t o f atmospheric head. In p r a c t i c e , t h e a c t u a l vapour p r e s s u r e o f water and t h e use o f a p o r t i o n o f t h e unbalanced head t o overcome t u r b u l e n c e , f r i c t i o n and t o a c c e l e r a t e t h e water column w i t h the  p i s t o n , t h e l i m i t o f water t a b l e depth t o which t h e  unbalanced head remains p o s i t i v e i s about 7 meters Health Organization  1977).  23  (World  24 Further  c o n s t r a i n t s on t h e o p e r a t i o n  include t h e l i m i t s of operator  o f t h e T r e a d l e pump  c a p a b i l i t i e s such as power  i n p u t , which v a r i e s w i t h weight, d i e t , c o n d i t i o n i n g , and  environmental c o n d i t i o n s such as temperature and  humidity.  The c o n d i t i o n and d e s i g n  o f t h e pump s e a l s and  v a l v e s , which can i n f l u e n c e t h e amount o f s l i d i n g and  health  friction  leakage p a s t t h e p i s t o n and t h e amount o f s u c t i o n head  a t t a i n a b l e , a l s o c o n s t r a i n pump  operation.  4.2 CALCULATION OF UNBALANCED HEAD 4.2.1 MINOR LOSSES Minor l o s s e s a r e those caused by t h e f r i c t i o n and turbulence Included  o f water a g a i n s t components o f t h e pump system.  a r e those from when i t e n t e r s t h e pump system a t  the f i l t e r u n t i l i t i s d i s c h a r g e d The  a t t h e pump spout.  l o s s e s from t u r b u l e n t flow through t h e expansions,  c o n t r a c t i o n s and f i t t i n g s were c a l c u l a t e d u s i n g  tabulated  l o s s c o e f f i c i e n t s (Roberson and Crowe 1985, 377), c a l c u l a t e d as a p r o p o r t i o n  o f v e l o c i t y head, and added t o t h e t o t a l  head l o s s o f t h e system. Losses r e s u l t i n g from t h e f r i c t i o n between t h e water and  flow  t h e uPVC r i s e r p i p e and t h e s t e e l pump body were  c a l c u l a t e d u s i n g t h e Darcy-Weisbach e q u a t i o n w i t h a f r i c t i o n f a c t o r o f 0.005 d e r i v e d Crowe 1985,  368).  from t h e Moody diagram  (Roberson and  Although  t h e r e a r e v a r i a t i o n s i n i n s t a l l a t i o n such as  r i s e r p i p e and f i l t e r  q u a l i t i e s t h a t can a f f e c t t h e amount  l o s s e s t h a t occur, t h e l o s s e s i n t h e l a b o r a t o r y t e s t apparatus  were kept c o n s t a n t from t e s t t o t e s t u s i n g a  s i n g l e r i s e r t o pump system.  T h i s allowed comparison o f t h e  measured l o s s e s t o those c a l c u l a t e d .  4.2.2 VALVE TIMING AND LEAKAGE V a l v e t i m i n g and leakage  i n a constant  differential  manual pump system a f f e c t s pump performance by d e c r e a s i n g d i s c h a r g e f o r a g i v e n energy i n p u t . In t h e T r e a d l e pump, d e l a y s i n p i s t o n v a l v e c l o s u r e r e s u l t s i n t h e o p e r a t o r e x e r t i n g e f f o r t t o t h e pump without l i f t i n g any water and reduces t h e volume o f water above t h e piston f o r discharge.  T h i s d e l a y reduces t h e f o r c e  r e q u i r e d , w i t h t h e r e d u c t i o n i n d i s c h a r g e , b u t consequently i n c r e a s e s t h e time pumping time r e q u i r e d t o meet t h e i r r i g a t i o n requirements.  Delays i n f o o t v a l v e c l o s u r e a l l o w  water i n t h e p i s t o n t o r e t u r n t o t h e r i s e r p i p e r e d u c i n g t h e d i s c h a r g e on t h e f o l l o w i n g s t r o k e . i n c r e a s i n g t h e energy requirement,  T h i s has t h e e f f e c t o f as a reduced  amount o f  water remains i n t h e pump as compared t o t h e amount f o r which energy was expended. Leakage through  t h e v a l v e s and p a s t t h e p i s t o n cup s e a l  a l s o reduces pump e f f i c i e n c y .  The leakage p a s t t h e p i s t o n  cup s e a l d u r i n g t h e upward s t r o k e r e s u l t s i n a r e d u c t i o n o f  26 the s u c t i o n head c r e a t e d below t h e p i s t o n and a l s o reduces the volume o f water above t h e p i s t o n t o be d i s c h a r g e d .  From  examination o f t h e v a l v e l i f t d i s t a n c e s , t h e v a l v e opening and c l o s i n g times,  and t h e t o t a l l o s s e s through l a b o r a t o r y  experiments, t h e p r o p o r t i o n o f l o s s through leakage p a s t t h e p i s t o n s e a l can be compared t o t h a t from v a l v e c l o s i n g delays. A measure f o r t h e amount o f water l o s t by v a l v e and  delays  leakage i s termed v o l u m e t r i c e f f i c i e n c y , d e f i n e d as t h e  r a t i o o f t h e volume o f water d i s c h a r g e d t o t h e volume swept by t h e p i s t o n i n t h e same time p e r i o d .  Although i t i s  p o s s i b l e t o o b t a i n v o l u m e t r i c e f f i c i e n c i e s o f g r e a t e r than one,  from t h e momentum e f f e c t s o f a water column, i t i s not  common i n manual pumps which have s m a l l i n p u t power and r e l a t i v e l y s m a l l water column momentum.  4.2.3 The  INERTIA s u c t i o n head r e q u i r e d t o a c c e l e r a t e t h e column o f  water i n t h e r i s e r p i p e i s dependent upon t h e l e n g t h o f t h e p i p e and t h e a c c e l e r a t i o n .  As t h e r i s e r l e n g t h i s f i x e d and  s e a l e d , t h e a c c e l e r a t i o n o f t h e water column i s a d i r e c t r e s u l t o f t h e a c c e l e r a t i o n o f t h e p i s t o n s , b u t l i m i t e d by the t o t a l unbalanced head a v a i l a b l e . The  p i s t o n motion c h a r a c t e r i s t i c s o f t h e T r e a d l e pump  were assumed t o be p e r i o d i c w i t h r e s p e c t t o time.  To f i n d  the g e n e r a l shape and t i m i n g o f t h e a c c e l e r a t i o n curve, an  27  cm  0.05  m/s  0.25  : m/s"2  0.5 TIME (Seconds)  F i g u r e 9:  C h a r a c t e r i s t i c p i s t o n motion  parameters.  approximation o f t h e form: Y(t) = ^avg where  +  A  s:  "- ( "t) n  w  y ( t ) = p i s t o n displacement w i t h r e s p e c t t o time (centimeters) avg A  median d i s t a n c e Amplitude Y  a v g  o f p i s t o n t r a v e l (cm)  o f p i s t o n displacement  about  (cm).  w = Angular v e l o c i t y (as i f p i s t o n was connected t o a c i r c u l a r crank mechanism) (radians/second)  28 t = time  (seconds)  was assumed t o be s u f f i c i e n t g i v e n t h e motion v a r i a t i o n s due t o o p e r a t o r and pump i r r e g u l a r i t i e s . one  p i s t o n , measured i n t h e l a b o r a t o r y  The p i s t o n motion, f o r i s shown i n f i g u r e 9.  I r r e g u l a r i t i e s from o p e r a t o r and pump v a r i a t i o n s a r e e s p e c i a l l y evident i n the calculated acceleration small v a r i a t i o n s  curve. The  i n p o s i t i o n over time, t h a t a r e not e v i d e n t  w i t h t h e r e s o l u t i o n o f p o s i t i o n graph, a r e r e v e a l e d .  An  approximation o f t h e motion shown i n f i g u r e 9, g i v e n below u s i n g t h e assumed s i n u s o i d a l  form, c o u l d be used t o  m a t h e m a t i c a l l y model t h e pump c h a r a c t e r i s t i c s .  y ( t ) = 3.6 + 1.5 s i n (14t - 2.6)  Although t h e approximation i s not a p r e c i s e measured motion parameters, i t i s s u f f i c i e n t l y  f i t t o the accurate  g i v e n t h e v a r i a t i o n s i n motion from t h e pump and o p e r a t o r . M a t h e m a t i c a l l y , t h i s should r e s u l t i n a maximum o r minimum acceleration,  t h e second d e r i v a t i v e o f t h e p o s i t i o n  e q u a t i o n , when t h e p o s i t i o n o f t h e p i s t o n maximum r e s p e c t i v e l y .  i s a t a minimum o r  A t t h e same minimum o r maximum p i s t o n  p o s i t i o n , the v e l o c i t y , the f i r s t d e r i v a t i v e of the p o s i t i o n e q u a t i o n , s h o u l d be zero.  The p l o t o f l a b o r a t o r y  measured  p o s i t i o n , v e l o c i t y and a c c e l e r a t i o n v e r s u s time, f i g u r e 9, shows c l o s e agreement on t h e maximums and minimums t o the  29 those expected from t h e mathematical d e r i v a t i o n s .  As such,  the assumption as t o t h e p e r i o d i c nature o f t h e T r e a d l e pump motion c h a r a c t e r i s t i c s was c o n s i d e r e d v a l i d . However, f o r t h e purposes o f a c c u r a t e l y p r e d i c t i n g t h e f o r c e s i n t h e pump from c a l c u l a t i o n , i n p u t s f o r p o s i t i o n , v e l o c i t y and a c c e l e r a t i o n were taken from t h e l a b o r a t o r y data r a t h e r than from t h e mathematical e x p r e s s i o n s .  This  assured t h a t t h e c a l c u l a t i o n o f t h e f o r c e i n p u t s c o u l d be compared d i r e c t l y w i t h t h e measured r e s u l t s w i t h o u t any e r r o r s induced by breaks o r i r r e g u l a r i t i e s i n t h e l a b o r a t o r y s t r o k e motion.  4.2.4 MECHANICAL LOSSES The one mechanical l o s s accounted f o r i n t h e pump model was t h e s l i d i n g f r i c t i o n between t h e pPVC p i s t o n s e a l and the s t e e l c y l i n d e r .  V a r i a t i o n s i n t h e form, c o n s i s t e n c y and  dimensions o f t h e p i s t o n cup s e a l s and pump c y l i n d e r s r e s u l t i n g from t h e manufacturing p r o c e s s , made a n a l y t i c a l c a l c u l a t i o n of the s l i d i n g f r i c t i o n d i f f i c u l t .  Given t h e  i n e x a c t n e s s o f t h e pump and t h e i n c o n s i s t e n c y between pumps, an e m p i r i c a l approximation o f 15 newtons, taken from l a b o r a t o r y d a t a o f d r y pump t e s t s , was adopted. Other mechanical l o s s e s , such as t h e f r i c t i o n i n t h e hook and p i n p i s t o n c o n n e c t i o n t o t h e bamboo t r e a d l e s , and t h e f r i c t i o n of the central s t e e l axle treadle pivot against the o s c i l l a t i n g t r e a d l e s , a l s o reduce t h e power e f f i c i e n c y from  30 the o p e r a t o r t o the pump. The l o s s e s was  s e p a r a t e measurement of these  beyond the scope o f t h i s t h e s i s but are  i n the assessment of the t o t a l l o s s e s o c c u r r i n g  estimated  i n the  T r e a d l e pump.  4.3  GOVERNING EQUATIONS For stage one  s e c t i o n 3.2  and  of the pump c y c l e , p r e v i o u s l y d e s c r i b e d shown i n f i g u r e 8, the f o r c e a p p l i e d t o  p i s t o n i s the sum  in the  o f the l i f t i n g of the p i s t o n mass, the  s l i d i n g f r i c t i o n between the p i s t o n s e a l and  the  cylinder  w a l l and  the drag f o r c e from the water flow through  piston.  I t i s assumed t h a t no water above the p i s t o n i s  l i f t e d by the s m a l l upward p i s t o n movement i n t h i s  the  stage  which o c c u r s b e f o r e the p i s t o n s e a l s e a l s a g a i n s t the piston plate, i.e.  no d i s c h a r g e i s produced.  The  lower  force  r e q u i r e d t o l i f t the p i s t o n i s dependent upon the mass of the p i s t o n , the unbalanced mass o f the t r e a d l e l e v e r and a c c e l e r a t i o n imparted t o them, the c o e f f i c i e n t o f o f the s e a l a g a i n s t the c y l i n d e r w a l l and the p i s t o n through the water.  The  the  friction  the v e l o c i t y of  equation to c a l c u l a t e  the  force required i s :  F =  where  ((M+M )*a ) + t  p  (H *w*a ) + F  F = f o r c e a p p l i e d t o the p i s t o n M = the p i s t o n mass  (kg)  d  p  (newtons)  f  (1)  31 = unbalanced mass o f t h e t r e a d l e l e v e r (kg) 2  a  = the acceleration of the piston  (m/s )  H  d  = head l o s s r e s u l t i n g from t h e d r a g f o r c e s (m)  F  f  = sliding friction  force 3  w = s p e c i f i c weight o f water (newtons/m ) with H  =  c *v d  2  E —  ( 2  )  2*g where C  d  = drag c o e f f i c i e n t  V  = v e l o c i t y o f t h e p i s t o n (m/s)  g  = g r a v i t a t i o n a l c o n s t a n t = 9.81 m/s  2  For s t a g e two, t h e c o m p l e t i o n o f t h e upstroke, t h e p i s t o n must produce s u f f i c i e n t s u c t i o n t o overcome t h e minor l o s s e s , a c c e l e r a t e t h e water column and m a i n t a i n  sufficient  unbalanced head t o produce flow from t h e water t a b l e t o t h e pump. T h i s s u c t i o n , expressed i n meters o f water, i s r e f e r r e d t o a s u c t i o n head (H).  The f o r c e a p p l i e d t o t h e  p i s t o n a l s o i n c l u d e s t h e f o r c e r e q u i r e d t o l i f t and a c c e l e r a t e t h e unbalanced t r e a l e l e v e r mass, and i s c a l c u l a t e d using the equation: F = (H*A *w) + F p  f  + ((M+M )*a ) t  p  (3)  32  where Ap = c r o s s - s e c t i o n a l p i s t o n area  (m ) 2  and H = - WT - h1 - hd  a r *1 r g  (4) g  where H AH WT h-^ h H  = = = = =  s u c t i o n head (m) atmospheric head (m) depth t o water t a b l e (m) t o t a l minor head l o s s e s t o t a l head l o s s from drag  = head r e q u i r e d t o a c c e l e r a t e t h e water column  g a *1 —E_ g  - head r e q u i r e d t o a c c e l e r a t e water i n t h e cylinder  In t h e t h i r d stage, from t h e end o f t h e u p s t r o k e t o t h e c l o s u r e o f t h e f o o t - v a l v e , t h e f o r c e s a c t i n g on t h e p i s t o n include the f r i c t i o n force of the seal against  the c y l i n d e r  and t h e drag f o r c e , from water e s c a p i n g through t h e c l o s i n g foot valve, movement.  a t t h e same r a t e as t h e p i s t o n downward The f o r c e a c t i n g on t h e p i s t o n i s a r e s u l t o f  g r a v i t y a c t i n g upon t h e unbalanced mass o f t h e t r e a d l e  lever  r a i s e d i n s t a g e one and two. In t h e f o u r t h stage, t h e p i s t o n c o n t i n u e s downward a f t e r the c l o s i n g o f t h e f o o t - v a l v e .  The f o r c e s from t h e s l i d i n g  f r i c t i o n and t h e drag o f t h e p i s t o n through t h e water a r e  33  c a l c u l a t e d u s i n g t h e sum o f t h e c o n s t a n t f r i c t i o n f o r c e and the drag f o r c e from e q u a t i o n  (2), w i t h t h e p i s t o n v e l o c i t y  s u b s t i t u t e d f o r t h e r i s e r flow v e l o c i t y .  This force i s also  s u p p l i e d by t h e unbalanced t r e a d l e l e v e r mass. As s t a t e d , t h e f o r c e s i n stages t h r e e exerted  and f o u r a r e not  by t h e o p e r a t o r but r a t h e r by g r a v i t y a c t i n g on t h e  mass o f t h e unbalanced p o r t i o n o f t h e t r e a d l e l e v e r , t h e p i s t o n and t h e c o n n e c t i n g p i n .  The unbalanced mass o f t h e  second t r e a d l e i s s i m u l t a n e o u s l y b e i n g l i f t e d o p e r a t o r when t h e f i r s t i s e x e r t i n g downward I t was i n c l u d e d  by t h e force.  i n t h e f o r c e c a l c u l a t i o n s f o r t h e upward  p o r t i o n o f t h e s t r o k e where t h e f o r c e i s e x e r t e d the  b u t because  f o r c e t r a n s d u c e r was l o c a t e d a t t h e p i s t o n r o d and  measured t h e f o r c e exerted  a t t h e p i s t o n , not t h e f o r c e  exerted  by t h e o p e r a t o r t o t h e t r e a d l e l e v e r s .  exerted  t o r a i s e t h e unbalanced mass o f t h e t r e a d l e  was i n c l u d e d  The f o r c e  i n t h e f o r c e and power i n p u t measurements by  measuring t h e f o r c e exerted  on t h e downward p o r t i o n o f t h e  s t r o k e by t h e unbalanced t r e a d l e mass.  T h i s was added i n t o  the power c a l c u l a t i o n s t o account f o r t h e l i f t i n g measured on t h e upward s t r o k e . effort  exerted  downward  lever  f o r c e not  The method o f adding t h e  by unbalanced t r e a d l e l e v e r mass on t h e  s t r o k e does not take i n t o account t h e f o r c e  d i f f e r e n c e s between t h e upward and downward acceleration. installed,  lever  I t was assumed t h a t i f t h e pump i s p r o p e r l y  t h e d i f f e r e n c e between t h e two i s minimal.  From t h e above e q u a t i o n s , c a l c u l a t i o n s f o r t h e f o r c e s a t d i f f e r e n t p i s t o n p o s i t i o n s , based on one t e n t h o f a second measurement  increments, were conducted w i t h t h e r e s u l t s  shown i n f i g u r e 9. abrupt i n l e t ,  A water t a b l e depth o f 3.34 meters, an  6.37 meters o f uPVC r i s e r p i p e w i t h a f r i c t i o n  c o - e f f i c i e n t o f f=0.0005, a box type j u n c t i o n  and t h e two  p l a t e s t a n d a r d p i s t o n l o s s c h a r a c t e r i s t i c s and t h e motion parameters taken from l a b o r a t o r y  t e s t s were used i n the  calculations. 5TN0 CONFIGURATION  400  : DEPTH TO V T = 3 . 3 4 M  300  200  -  150  -  100  -  PISTON POSTION  ccentimeterS3  F i g u r e 10: An example o f c a l c u l a t e d laboratory  measured i n p u t  force r e s u l t s with  parameters.  5 LABORATORY TESTING 5.1 APPARATUS DESIGN CONSIDERATIONS The l a b o r a t o r y apparatus  d e s i g n r e q u i r e d a c a r e f u l mix o f  s t r e n g t h and s e n s i t i v i t y t o balance t h e i m p r e c i s e c h a r a c t e r i s t i c s o f t h e T r e a d l e pump, r e s u l t i n g from manufacture and d e s i g n f o r o p e r a t i o n i n Bangladesh, and the p r e c i s i o n r e q u i r e d f o r a c c u r a t e measurement o f performance characteristics.  O b t a i n i n g a measurement accuracy o f twenty  newtons, without t h e d e s t r u c t i o n o f t h e s e n s i t i v e measuring apparatus  by t h e l a r g e f o r c e and displacement  fluctuations  i n h e r e n t i n t h e pump, i n v o l v e d t h e d e s i g n o f a s p e c i a l i z e d force transducer. T h i s was a c h i e v e d through  repeated d e s i g n and t e s t i n g o f  a l t e r n a t e d e s i g n s over a p e r i o d o f t h r e e months t o o b t a i n t h e c o r r e c t balance between s e n s i t i v i t y and d u r a b i l i t y .  The  a d d i t i o n o f s i g n a l a m p l i f i c a t i o n and c o n d i t i o n i n g f i n a l l y enabled t h e t e s t i n g t o be conducted parameters.  within the required  In a d d i t i o n , t h e use o f a h i g h l y s t a b l e  s u p e r s t r u c t u r e and wide range i n p u t t r a n s d u c e r s f o r l i n e a r motion measurement was a l s o necessary t o ensure accuracy and a h i g h degree o f s e n s i t i v i t y . The m o d i f i e d s t e e l s u p e r s t r u c t u r e , pump attachment and w e l l s t r u c t u r e i n c r e a s e d s t a b i l i t y compared t o t h e bamboo 35  commonly used i n Bangladesh.  Used i n c o n j u n c t i o n  with  pumps, s e a l s and p i s t o n s u n a l t e r e d from manufacture i n Bangladesh, t h e f o r c e and displacement minimized without  f l u c t u a t i o n s were  compromising t h e o p e r a t i n g  characteristics  o f t h e pump. Force  i n p u t s t o t h e pump v i a t h e p i s t o n s were measured  u s i n g a t u b u l a r s t r a i n gauge f o r c e t r a n s d u c e r w i t h  F i g u r e 11: Instrumentation  reduced  f o r the laboratory t e s t s .  w a l l t h i c k n e s s t o o b t a i n maximum s e n s i t i v i t y mounted as p a r t o f t h e p i s t o n r o d as shown i n f i g u r e 11. The t u b u l a r transducer  was machined from aluminum, p r o v i d i n g maximum  s t a b i l i t y a g a i n s t bending and b u c k l i n g  from l a r g e loads but  r e t a i n i n g t h e s e n s i t i v i t y r e q u i r e d t o a c c u r a t e l y read t h e s m a l l f o r c e changes o c c u r r i n g d u r i n g t h e pump c y c l e .  Two  d i a m e t r i c a l l y opposed s t r a i n gauges were a f f i x e d t o t h e transducer bridge  and connected i n o p p o s i t e  arms o f t h e wheatstone  circuit.  T h i s c a n c e l l e d t h e bending f o r c e s r e s u l t i n g from t h e o f t e n e c c e n t r i c nature o f t h e p i s t o n t o c y l i n d e r s l i d i n g f o r c e s , t h e roughness o f t h e hook p i n c o n n e c t i o n  of the  p i s t o n t o t h e t r e a d l e and t h e arced motion o f t h e c e n t r a l l y p i v o t e d t r e a d l e l e v e r which r e s u l t e d i n a n g u l a r displacement o f t h e p i s t o n through t h e pump c y c l e . was  The f o r c e  transducer  a l s o temperature compensated u s i n g two 12 0 ohm r e s i s t o r s  mounted b e s i d e  the transducer  connected t o a d j a c e n t  on t h e pump frame and  arms o f t h e b r i d g e c i r c u i t  from t h e  s t r a i n gauges. The b r i d g e c i r u i t was balanced by t h e use o f a v a r i a b l e r e s i s t a n c e c i r c u i t connected i n s e r i e s w i t h one o f t h e temperature compensating The  resistors.  s t r o k e p o s i t i o n was instrumented u s i n g a l i n e a r  v a r i a b l e distance transducer r i g h t hand s i d e  (LVDT) mounted between t h e  (from t h e operator) p i s t o n p i n and t h e  v e r t i c a l u p r i g h t p o s t s o f t h e pump s t r u c t u r e .  I t was  38  F i g u r e 12:  Laboratory  apparatus.  mounted w i t h p i v o t c o n n e c t i o n s a t both ends t o p r e v e n t bending o f the t r a n s d u c e r due t o the a r c o f the t r e a d l e l e v e r throughout the s t r o k e . ten  The LVDT was  supplied with a  v o l t e x c i t a t i o n v o l t a g e from a r e g u l a t e d d i r e c t c u r r e n t  power s u p p l y . The d a t a from the t r a n s d u c e r s was  c o n d i t i o n e d u s i n g an  a m p l i f i e r t o boost the f o r c e t r a n s d u c e r s i g n a l 1000 to  a l e v e l u s a b l e by the analog t o d i g i t a l  analog t o d i g i t a l  times,  converter.  c o n v e r t e r allowed f o r data c o l l e c t i o n  s t o r a g e by a p e r s o n a l computer.  The and  U s i n g a B a s i c language  computer program, data i n p u t t i m i n g was  c o n t r o l l e d and  data  39 was c o l l e c t e d from t h e analog t o d i g i t a l c o n v e r s i o n board i n t o t h e computer memory a t a r a t e o f 10 r e a d i n g s p e r second. The use o f a h i g h c o l l e c t i o n r a t e enabled t h e f o r c e peaks and d e l a y s a t t h e p i s t i o n t o be d e t e c t e d and a n a l y z e d but r e s u l t e d i n v e r y l a r g e data s e t s .  A n a l y s i s o f t h e data  u s i n g spreadsheet based programs became v e r y time consuming and was somewhat l i m i t e d due t o t h e l a r g e s i z e o f each o f t h e 64 data s e t s . f i v e minutes,  The d u r a t i o n o f each t e s t was l i m i t e d t o  a t t h e t e n h e r t z c o l l e c t i o n r a t e , by t h e  amount o f i n t e r n a l memory a v a i l a b l e i n t h e p e r s o n a l computer and by t h e s t o r a g e media where t h e data was s t o r e d f o r l a t e r processing.  The B a s i c language program was a l s o used t o  c o n v e r t t h e data from raw c o n v e r t e r r e a d i n g s t o d a t a s u i t a b l e output f o r l a t e r a n a l y s i s u t i l i z i n g p r e v i o u s l y measured c a l i b r a t i o n f a c t o r s .  The o v e r a l l t e s t i n g s t r u c t u r e  i s shown i n f i g u r e 12. U s i n g f r e e weights  and a measuring s c a l e , t h e f o r c e and  d i s t a n c e i n s t r u m e n t a t i o n was i n i t i a l l y c a l i b r a t e d and t h e c a l i b r a t i o n f a c t o r s re-checked  a f t e r every f o u r t e s t s .  5.2 TESTING PROCEDURE The were:  f i v e s t e p s o f t h e procedure  for the laboratory tests  40 1) I n s p e c t i o n o f pump components and t r i a l pump o p e r a t i o n to  check f o r worn out components, any problems such as  leakage and t o o b t a i n uniform pump o p e r a t i o n . 2) The computer data c o l l e c t i o n channels were zeroed where a p p r o p r i a t e and t h e i n i t i a l  l e v e l o f water i n t h e  d i s c h a r g e c o l l e c t i o n tank was read and r e c o r d e d . 3) With data c o l l e c t i o n s t a r t e d , t h e zero r e a d i n g s f o r the f o r c e and p o s i t i o n t r a n s d u c e r s were r e c o r d e d f o l l o w e d by p r i m i n g o f t h e pump.  A f t e r a pause, t o i n d i c a t e t h e  b e g i n n i n g o f d i s c h a r g e i n t h e c o l l e c t e d data s e t , t h e pump was  operated f o r between 4 and 6 minutes,  d u r i n g which time  t h e d a t a was c o l l e c t e d from t h e f o r c e t r a n s d u c e r , t h e LVDT, the LVDT and s t r a i n gauge v o l t a g e s u p p l i e s and t h e computer t i m e r a t a r a t e o f t e n r e a d i n g s p e r second. 4) On completion o f pumping, t h e data c o l l e c t i o n program was  stopped and t h e data down loaded t o a data f i l e on  f l o p p y d i s k f o r c o n v e r s i o n from raw r e a d i n g s and a n a l y s i s u s i n g a spreadsheet based program. 5) The water l e v e l i n t h e d i s c h a r g e c o l l e c t i o n tank was read and r e c o r d e d a l o n g w i t h t h e number o f r e a d i n g s taken by the data c o l l e c t i o n system and t h e e l a p s e d r e a l time f o r comparison and e r r o r checking o f t h e computer c o l l e c t e d data. The t o t a l time t h a t data c o u l d be c o l l e c t e d i n one t e s t was  c o n s t r a i n e d by t h e i n t e r n a l memory l i m i t s o f t h e  computer used and by t h e s i z e o f d a t a f i l e s t o r a b l e on a  41 s i n g l e d a t a s t o r a g e d i s k e t t e and r e a d a b l e by t h e spreadsheet program used  f o r data a n a l y s i s .  C o l l e c t i o n times  than f i v e minutes were found t o exceed  longer  these c o n s t r a i n t s .  5.3 DATA REDUCTION AND ANALYSIS The d a t a f i l e s  r e s u l t i n g from t h e data  collection  computer program were t r a n s f e r r e d t o a spreadsheet using floppy disks. d a t a was imported,  U s i n g t h e spreadsheet  program  functions, the  reduced and analyzed u s i n g t h e f o l l o w i n g  steps: 1) The f i r s t p o r t i o n o f c o l l e c t e d data, taken w i t h t h e pump a t r e s t , was averaged  t o o b t a i n a raw data r e a d i n g  e q u a t i n g t o t h e zero p o i n t f o r each c o l l e c t e d v a r i a b l e . These i n i t i a l  zero r e a d i n g s were a l s o used t o check f o r  d e v i a t i o n s i n data caused by v a r i a t i o n s i n e x c i t a t i o n voltage supply o r c i r c u i t r y voltage v a r i a t i o n . average  I f the  o f t h e data c o l l e c t e d w i t h t h e pump a t r e s t v a r i e d  more than 10% from t h e average n o r m a l i z e d t o t h e average repeated.  o f t h e complete data s e t ,  supply v o l t a g e , then t h e t e s t was  U s u a l l y only the i n i t i a l t e s t i n a given s e r i e s  was prone t o l a r g e supply v o l t a g e and subsequent data v a r i a t i o n s due t o c i r c u i t r y h e a t i n g w i t h i n t h e v o l t a g e supply, f o r c e t r a n s d u c e r a m p l i f i e r and s t r a i n gauge b r i d g e circuits.  Small v a r i a t i o n s i n t h e data s e t about t h e  average were p e r m i t t e d , as t h e area under t h e f o r c e displacement  curve remained c o n s t a n t .  The s m a l l p o s i t i v e  42 and n e g a t i v e v a r i a t i o n s c a n c e l each o t h e r out i n the c a l c u l a t i o n o f the o v e r a l l area encompassed by the curve. 2) I f the data was  w i t h i n the a c c e p t a b l e l i m i t s f o r  v a r i a t i o n , then the zero r e a d i n g s were r e c o r d e d and t h e data c o l l e c t e d d u r i n g z e r o i n g , p r i m i n g and between the  completion  of pumping and the s t o p p i n g of data c o l l e c t i o n , was 3) The  f o r c e and p o s i t i o n data was  removed.  then c o n v e r t e d t o  a p p r o p r i a t e u n i t s from the raw data r e a d i n g s , u s i n g the c a l i b r a t i o n f a c t o r s and zero p o i n t d a t a . 4) C a l c u l a t i o n s f o r work and power were then  calculated  on a time i n c r e m e n t a l b a s i s from the p i s t o n p o s i t i o n , and f o r c e i n p u t s . unbalanced  time  The c a l c u l a t i o n of power used t o l i f t  t r e a d l e l e v e r mass d u r i n g the p i s t o n  the  upstroke,  l a t e r p r o v i d i n g the f o r c e f o r the downstroke, was  calculated  from t h e f o r c e measured a t the p i s t o n d u r i n g the downstroke and added t o t h a t c a l c u l a t e d f o r the u p s t r o k e . r a t e , t o t a l swept volume and average  The  stroke length  stroke was  c a l c u l a t e d u s i n g the e n t i r e data s e t . U s i n g the d i s c h a r g e data, c a l c u l a t e d from the r e a d i n g s taken on the c a l i b r a t e d d i s c h a r g e c o l l e c t i o n tank,  the  p i s t o n p o s i t i o n and t i m i n g v a l u e s , the v o l u m e t r i c e f f i c i e n c y , power output and, u s i n g the average  o f the  c a l c u l a t e d power v a l u e s , power e f f i c i e n c y r e s u l t s were calculated.  6 FIELD TESTING 6.1 APPARATUS DESIGN CONSIDERATIONS The apparatus d e s i g n f o r t h e f i e l d t e s t s was c o n s t r a i n e d by f o u r  factors.  F i r s t l y , the l i m i t e d a c c e s s i b i l i t y of the t e s t s i t e s . All  equipment and p e r s o n n e l reached t h e s i t e s by a  combination o f r i v e r boats, m o t o r c y c l e s and w a l k i n g . Secondly, t h e u n a v a i l a b i l i t y and u n s u i t a b i l i t y o f sophisticated  t e s t equipment such as t h a t used i n t h e  l a b o r a t o r y due t o extreme environmental c o n d i t i o n s and t h e lack of t r a n s p o r t a b i l i t y , facilities Thirdly,  component  fabrication  and power a v a i l a b i l i t y . t h e v a r i a b i l i t y o f pump i n s t a l l a t i o n s i n terms  of o v e r a l l c o n d i t i o n , parameters  repair,  set-up dimensions and o p e r a t i o n  and f o u r t h l y ,  the l i m i t to disruption  o f pumping  a c t i v i t i e s f o r t e s t i n g i n terms o f both time and a l t e r a t i o n of t h e pump f i e l d  situation.  Any undue d i s r u p t i o n  could  have had t h e e f f e c t o f minor crop damage due t o nonirrigation,  l o s s o f income f o r t h e h i r e d  the pump i f h i r e d  labour operating  l a b o u r was used, and undue e x p e n d i t u r e by  l o c a l farmers f o r food and d r i n k s i n t h e i r e f f o r t s t o befriend  and impress t h e t e s t e r s .  43  44  The  r e s u l t i n g apparatus d e s i g n u t i l i z e d two, t h i r t y  measurement pans, an e l e c t r i c a l water l e v e l sensor  litre  circuit  a t t a c h e d t o a tape measure, a two h o l e o f f s e t clamp t o a t t a c h a pen t o t h e p i s t o n rod, a c l i p b o a r d / p a p e r h o l d e r and four a d d i t i o n a l personnel. As i n t h e l a b o r a t o r y t e s t s , parameters f o r d i s c h a r g e , s t r o k e l e n g t h , s t r o k e number and t e s t time needed t o be measured.  Discharge was measured by a l t e r n a t e f i l l i n g and  dumping o f t h e two measuring pans, s t r o k e l e n g t h was measured by r e p e a t e d l y s l i d i n g t h e c l i p b o a r d h e l d paper a l o n g t h e h o l d e r and measuring t h e r e s u l t i n g t r a c e s from a pen o r marker mounted t o t h e p i s t o n r o d .  T h i s method f o r  measured s t r o k e l e n g t h was a l t e r e d somewhat from pump t o pump depending upon t h e ground s u r f a c e s u r r o u n d i n g  t h e pump,  the pump i n s t a l l a t i o n , t h e a p p l i c a b i l i t y o f u s i n g t h e c l i p b o a r d h o l d e r and t h e d i f f i c u l t i e s i n a f f i x i n g t h e pen o r marker t o t h e p i s t o n r o d . was  I n a few cases, t h e s t r o k e l e n g t h  measured by o b s e r v a t i o n o f t h e s t r o k e a g a i n s t a  measuring tape as t h e i n s t a l l a t i o n d i d n o t a l l o w f o r a f f i x i n g a marker t o t h e p i s t o n r o d without destruction.  i t s rapid  Stroke number was counted by one o f t h e  a d d i t i o n a l personnel  and t h e t e s t was timed  from s t a r t t o  stop by a stop watch. The  apparatus was simple i n d e s i g n and was found t o be  v e r y adaptable understood  t o v a r i a t i o n s i n t e s t s i t u a t i o n s and e a s i l y  by t h e t e s t p e r s o n n e l .  The apparatus was labour  45  i n t e n s i v e , by North American standards, b u t was a p p r o p r i a t e for  use i n Bangladesh, where l a b o u r i s r e a d i l y a v a i l a b l e and  l e s s expensive than t h e c o s t w i t h i n c r e a s e d apparatus complexity.  Given t h e c o n d i t i o n s f o r t h e t e s t i n g , t h e  apparatus was found t o be a p p r o p r i a t e .  6.2 TEST LOCATIONS AND PROCEDURE Forty-one T r e a d l e pumps were t e s t e d i n t h e f i e l d ten  tests,  i n t h e Jamalpur and Sherpur r e g i o n s i n n o r t h c e n t r a l  Bangladesh, and t h i r t y - t h r e e i n t h e K u s h t i a and Pabna r e g i o n s i n western Bangladesh as shown i n f i g u r e 11. Research i n t o pump d e s i g n and a l t e r n a t i v e s was conducted i n the  Kurigram r e g i o n i n Northern Bangladesh and i n t h e  Shonargoan r e g i o n j u s t south o f Dhaka. The t e s t procedure v a r i e d somewhat from s i t e t o s i t e depending upon how t h e pump was s i t u a t e d and s e t up i n t h e field  and t h e degree o f c o - o p e r a t i o n from t h e farmer owner-  operator or h i r e d operator.  I n g e n e r a l , t h e procedure was  as f o l l o w s : 1) With p e r m i s s i o n from t h e owner and o p e r a t o r , s o i l below t h e pump spout was removed, i f necessary, t o permit placement and removal o f t h e d i s c h a r g e measurement pans below t h e d i s c h a r g e spout.  46 Scale l'= 80 Miles Partchagarti REFERENCES . ,ni*,'  InternoHonal  iNiiphama.  District  Boundary . .  Boundary  RaiJwoy RiveiA i r Port  vlhet  Moulvi bazar  \VManikgonj\D|} " 'i. al  IMeherpur^r-r.  i  \  ?/, rf Brahmanbaria  ••.17  ^huadanga  tA  f  Faridpur  •jfJhenaidah Magura 1 \  Jessore  '  'Munshigani [_ ,, ^  J  Narailc x  ^  X\. Gopalgan, \/7^  £_Perojpur  1  ( '  JtA.^N^j v.  "»  tSatkhira  Figure 13: L o c a t i o n o f f i e l d  tests,  47 2) The owner o f t h e pump was asked about t h e age o f t h e pump, dates o f most r e c e n t component replacements, and type o f r i s e r and f i l t e r , encountered w i t h t h e pump.  and i f any problems had been  The pump o p e r a t o r ,  owner, was asked h i s o r h e r age, the pump was operated  depth  often the  weight and number o f hours  p e r day d u r i n g t h e d r y season t o g a i n  i n s i g h t i n t o o p e r a t o r s t y p i c a l l y u s i n g t h e pump. responses were recorded t o p r o v i d e  The  information t o a s s i s t i n  d e s i g n a l t e r a t i o n c o n s i d e r a t i o n s and t o s i g n a l any s i g n i f i c a n t d e v i a t i o n s from t y p i c a l pump usage which might a f f e c t t h e data  collected.  3) The pump c y l i n d e r s , p i s t o n s , cup s e a l s and f o o t - v a l v e s were i n s p e c t e d f o r s i g n s o f undue wear and improper operation. to  I f t h e components were i n such poor c o n d i t i o n as  be n o n - r e p r e s e n t a t i v e  o f normally  used and maintained  pumps, then t h e t e s t was abandoned and t h e t e s t moved t o t h e next  site.  4) A f t e r f i v e t o t e n minutes o f pumping t o o b t a i n as normal a s u s t a i n a b l e pumping r a t e as p o s s i b l e , t h e depth t o water t a b l e was measured u s i n g t h e e l e c t r i c a l measuring tape lowered i n t o t h e r i s i n g main through t h e f o o t - v a l v e and j u n c t i o n box. the i n i t i a l  The measuring o f t h e water t a b l e depth a f t e r  pumping and draw down r e s u l t e d a depth t h a t  would be c o n s i s t e n t w i t h s u s t a i n e d pump o p e r a t i o n . 5) The clamping mechanism t h a t a t t a c h e d t h e pen o r marker to  t h e p i s t o n r o d was a t t a c h e d on t h e upper p o r t i o n o f t h e  48 p i s t o n , so as not t o i n t e r f e r e w i t h pump o p e r a t i o n , and a pen was a l s o a t t a c h e d a t r i g h t angles t o t h e p i s t o n . 6) The o p e r a t o r was i n s t r u c t e d t o pump as i f t h e t e s t  was  f o u r hours i n d u r a t i o n , t o o b t a i n u s u a l s u s t a i n a b l e pumping rates.  A f t e r f i v e minutes o f pumping o r when t h e s t r o k e  r a t e slowed and became c o n s i s t e n t , t h e t i m i n g and s t r o k e c o u n t i n g was s t a r t e d and the d i s c h a r g e measuring pan was p l a c e d under t h e spout. 7) A t l e a s t f o u r t r a c e s o f t h e s t r o k e motion were made, spaced a t about one minute i n t e r v a l s , t h e d i s c h a r g e measuring pans were removed and emptied when f u l l w i t h as l i t t l e s p i l l a g e as p o s s i b l e and t h e t i m i n g and s t r o k e c o u n t i n g were continued.  The minimum t e s t d u r a t i o n was  four  minutes and the maximum was t e n minutes. 8) I f t h e s t r o k e r a t e and l e n g t h were c o n s i s t e n t over the first  f o u r minutes o f t e s t i n g , then the data c o l l e c t i o n  stopped a t t h e next f u l l measuring pan. t e s t was c o n t i n u e d incremental  was  I f not, then the  f o r as long as 10 minutes w i t h  data v a l u e s recorded t o o b t a i n t h e data f o r the  most c o n s i s t e n t pumping. 9) F o l l o w i n g completion recorded  o f the t e s t , t h e data  on data c o l l e c t i o n sheets  f o r future analysis.  the pump was mounted on an uPVC r i s e r and f i l t e r , t e s t s were repeated  was  then the  u s i n g t h e author as t h e o p e r a t o r f o r  comparison t o the l a b o r a t o r y data.  If  49  10) of  Upon completion  o f t h e t e s t i n g , t h e owner was a d v i s e d  any r e p a i r s o r maintenance r e q u i r e d on t h e pump t o  improve performance and t h e pump s e t up was r e t u r n e d t o as near i t s o r i g i n a l c o n f i g u r a t i o n as p o s s i b l e , u n l e s s asked t o do otherwise, b e f o r e l e a v i n g t h e t e s t  6.3  location.  DATA ANALYSIS The d a t a from t h e f i e l d  t e s t s had l a r g e v a r i a t i o n s due t o  d i f f e r e n c e s i n pump c o n d i t i o n , o p e r a t o r s i z e and m o t i v a t i o n and t u r n o v e r i n c o l l e c t i o n p e r s o n n e l . I n a n a l y z i n g t h e data, o n l y severe o u t - l i e r s , those n o t p h y s i c a l l y p o s s i b l e , were removed. The  s t r o k e l e n g t h s were measured u s i n g t h e v e r t i c a l  d i s t a n c e from t h e trough t o t h e peak on t h e t r a c e . m u l t i p l e t r a c e s f o r each t e s t were averaged  The  t o obtain the  s t r o k e l e n g t h used i n c a l c u l a t i o n s t o determine t h e t o t a l swept volume necessary  f o r calculating the volumetric  e f f i c i e n c y o f t h e pump. The d i s c h a r g e volume was c a l c u l a t e d from t h e number o f d i s c h a r g e pans f i l l e d pans.  and t h e r e s p e c t i v e volumes o f t h e  The pan volume was a d j u s t e d based on o b s e r v a t i o n o f  how f u l l t h e pans were f i l l e d d u r i n g t h e t e s t and on how much unmeasured d i s c h a r g e o c c u r r e d on t h e s w i t c h i n g o f t h e pans. T y p i c a l l y t h i s adjustment ranged from a seven t o twenty p e r c e n t r e d u c t i o n i n t h e measured d i s c h a r g e , as t h e  50 pans were r a r e l y completely was  f u l l on removal and l i t t l e  l o s t d u r i n g the s w i t c h i n g o f the pans.  water  The v a r i a t i o n i n  adjustment was dependent upon the performance o f t h e p e r s o n a l removing and r e p l a c i n g t h e pans d u r i n g a p a r t i c u l a r t e s t , which was  recorded  f o r each t e s t .  The v o l u m e t r i c e f f i c i e n c y was of  c a l c u l a t e d u s i n g the r a t i o  t h e t o t a l swept volume, c a l c u l a t e d from t h e number of  s t r o k e s and t h e s t r o k e l e n g t h s t o t h e measured d i s c h a r g e . U s i n g t h e depth t o water t a b l e and t h e d i s c h a r g e c o l l e c t e d , t h e i n p u t power t o the pump was  estimated  on t h e depth-discharge-power output r e s u l t s from t h e laboratory  tests.  data based  7 RESULTS 7.1 PUMP FORCES The  f o r c e displacement curves, generated from t h e  laboratory  t e s t s , a r e u s e f u l f o r measuring t h e changes i n  f o r c e s a p p l i e d t o t h e p i s t o n throughout t h e f o u r stages o f the p i s t o n s t r o k e . in friction, pipe,  These changes a r e a r e s u l t o f v a r i a t i o n s  a c c e l e r a t i o n o f t h e water column i n t h e r i s e r  f o r m a t i o n o f t h e unbalanced head, and t h e use o f t h e  p o t e n t i a l energy s t o r e d i n t h e r a i s e d t r e a d l e l e v e r mass t o p r o v i d e t h e energy f o r t h e downward p i s t o n s t r o k e .  Pump  c o n f i g u r a t i o n , p i s t o n and f o o t - v a l v e d e s i g n a l s o cause f o r c e v a r i a t i o n s t h a t a r e o f p a r t i c u l a r i n t e r e s t i n pump  design.  Taking a d e t a i l e d look a t the i n i t i a l p o r t i o n of the f o r c e c u r v e s , t h e l a r g e f o r c e s a t t h e s t a r t o f t h e upstroke, evident  i n f i g u r e s 14 and 15, r e s u l t from t h e l a r g e  forces  r e q u i r e d t o a c c e l e r a t e t h e water column i n t h e r i s e r p i p e and  t h e water above t h e p i s t o n from r e s t , o r n e a r l y so, t o  equal t h e v e l o c i t y o f t h e p i s t o n a t t h a t same p o i n t i n t h e stroke.  I n comparing t e s t s u s i n g t h e s t a n d a r d two p l a t e  p i s t o n and t h e No.6 p i s t o n , shown i n f i g u r e s 14 and 15 r e s p e c t i v e l y , two d i f f e r e n c e s i n a c c e l e r a t i o n f o r c e s a r e evident.  51  52  WATER TABLE DEPTH: 3.36 meters  400  2.3  3.3  4.5  3.3  6.5  PISTON POST I ON ccentlmeters}  F i g u r e 14: Force-displacement loop u s i n g t h e two-plate type p i s t o n .  F i r s t l y , the peak a c c e l e r a t i n g f o r c e o c c u r s much more r a p i d l y a f t e r the v a l v e c l o s i n g i n the standard two-plate p i s t o n compared t o the s m a l l e r w i t h t h e No. 6 p i s t o n .  slope  following valve  closure  However, t h e maximum f o r c e s  r e s u l t i n g from a c c e l e r a t i o n o f the water columns a r e c l o s e to equal,  given  o p e r a t o r v a r i a t i o n s , and a l s o o c c u r a t the  same p o s i t i o n i n t h e s t r o k e .  The d i f f e r e n c e i n t h e s l o p e s  i n t h e i n i t i a l p o r t i o n o f t h e curves  i s a r e s u l t of the  combined e f f e c t o f t h e f a s t e r v a l v e c l o s i n g time o f t h e No.6 WATER TABLE DEPTH : 5.34 meters  400  330  <J  200  -  130  100  _  5  °  "1  2.6  1  1  3  1  1  3.4  1  1  3.B  1  1  4.2  r  4.6  ~i  5  1  1  5.4  1  1  r—  5.B  5.2  PISTON POSITION c c e n t l m e t e r e }  F i g u r e 15: Force-displacement  loop u s i n g t h e No.6 type  pistons.  p i s t o n , i n d i c a t e d by t h e r a p i d i n c r e a s e i n p i s t o n f o r c e e a r l i e r i n t h e s t r o k e , and t h e e f f e c t o f g r e a t e r  initial  leakage through and by t h e No. 6 p i s t o n , which i s i n d i c a t e d by t h e f l a t t e r s l o p e o f t h e f o r c e curve piston.  f o r t h e No. 6  The e q u i v e l e n t maximum f o r c e s i n d i c a t e s t h a t t h e  two p i s t o n s s e a l e q u a l l y by t h e end o f t h e s t r o k e . Secondly, t h e standard p i s t o n shows a sharp decrease i n f o r c e o f 100 t o 150 newtons a t mid-upstroke f o l l o w e d by an  54 increase  i n f o r c e o f 50 t o 100 newtons a t t h e completion o f  the u p s t r o k e .  T h i s i s not e v i d e n t w i t h t h e No. 6 p i s t o n ,  which has a more constant explanations  f o r c e throughout t h e s t r o k e .  Two  of t h i s force v a r i a t i o n are:  1) That t h e water column and p i s t o n r o d e x h i b i t e l a s t i c p r o p e r t i e s r e s u l t i n g from t h e r a p i d v a l v e c l o s u r e and r e s u l t i n g shock f o r c e s . T h i s e l a s t i c e f f e c t i s much l i k e a s t r e t c h i n g and subsequent rebounding.  The e l a s t i c e f f e c t s  of a manual pump water column was documented, t o e x p l a i n s i m i l a r f o r c e v a r i a t i o n b e h a v i o r , i n t h e t e s t i n g o f deep s e t hand-pumps (Yau 1985).  Although t h e documented f o r c e  v a r i a t i o n i s s i m i l a r t o t h a t measured on t h e T r e a d l e pump, the much s h o r t e r p i s t o n r o d o f t h e T r e a d l e pump and t h e r e s u l t i n g e l a s t i c e f f e c t o f t h e pump r o d i s n e g l i g i b l e , compared t o t h e t e n meter r o d used i n t h e a n a l y s i s by Yau. The  r e s u l t s a r e s t i l l u s e f u l however.  The r e p o r t  (Yau 1985)  concluded t h a t t h e magnitude o f t h e l a r g e f o r c e i n c r e a s e was required f o r the design  o f pump components t o w i t h s t a n d t h e  shock l o a d i n g , but t h a t t h e o v e r a l l area under t h e f o r c e d i s p l a c e m e n t curve d i d not t o change.  S i m i l a r l y f o r the  a n a l y s i s o f t h e T r e a d l e pump f o r c e displacement curves, t h e reductions  i n p i s t o n f o r c e s were found t o be e f f e c t i v e l y  c a n c e l l e d by t h e i n c r e a s e s , measured over t h e e n t i r e s t r o k e l e n g t h , r e s u l t i n g i n a c o n s i s t e n t work i n p u t measurement.  55 2) The  f o r c e v a r i a t i o n c o u l d a l s o be caused by  d e f o r m a t i o n of the p i s t o n s e a l i n the two piston.  T h i s would cause b i n d i n g  c y l i n d e r w a l l as the p i s t o n cup  the  p l a t e standard  of the s e a l a g a i n s t  the  s e a l would deform under the  maximum combined f o r c e s o f head l o s s , head requirements acceleration.  The  u n r e s t r i c t e d p i s t o n s e a l i s able  and  to  r o t a t e about i t s l e a d i n g edge, the upper c i r c u m f e r e n c e , from the combined moment c r e a t e d by the downward f o r c e s  of  f r i c t i o n , unbalanced s u c t i o n head and  forces  acceleration  a c t i n g on the o u t e r edge o f the s e a l and the upward motion o f the p i s t o n a c t i n g on the and  inward edge.  sudden a c c e l e r a t i o n f o r c e , e v i d e n t  p l a t e p i s t o n , i s followed  The  l o s s o f s u c t i o n from s e a l  deformation.  The  i n f o r c e a few  i n the s t r o k e  c o u l d be caused by the cup  centimeters  later  seal re-sealing  r e g a i n i n g the s u c t i o n f o r c e s .  r e - s e a l i n g o c c u r s as the downward deforming f o r c e s on s e a l are reduced and  two  i n force,  caused by poor s e a l i n g and  a g a i n s t the c y l i n d e r and  large  w i t h the s t a n d a r d  by a sudden r e d u c t i o n  increase  lifting  the shape memory i n h e r e n t  The the  with  temperature s e t p l a s t i c s , such as pPVC, r e t u r n the s e a l t o i t s o r i g i n a l un-deformed shape.  In comparison, deformation  o f the s e a l by r o t a t i o n about i t s c i r c u m f e r e n c e edge i s not p o s s i b l e w i t h the No. between two  threaded  6 p i s t o n as the s e a l i s s o l i d l y f i x e d fittings.  Given t h a t the f o r c e r e d u c t i o n s stroke  are not c o n s t a n t w i t h the  and  increases  through  the  f i x e d r i s e r l e n g t h used i n  56 the l a b o r a t o r y t e s t s , and t h a t the No.  6 p i s t o n d i d not show  t h i s c h a r a c t e r i s t i c curve when maximum s e a l i n g and a c c e l e r a t i o n f o r c e curves o c c u r r e d explanation,  steep  i n some t e s t s , the second  t h a t of the deformation of the p i s t o n s e a l , i s  the most p r o b a b l e .  T h i s i s not c o n c l u s i v e l y p r o v a b l e  the t e s t apparatus and More i m p o r t a n t l y ,  r e s u l t s of t h i s t h e s i s .  t o the improvement o f the pump design,  the f o r c e curve when u s i n g the No.6  p i s t o n i s smoother w i t h  l e s s shock l o a d i n g on the p i s t o n than w i t h two-plate due  t o s h o r t e r v a l v e c l o s i n g times and p r o b a b l y  deformation.  The  7.2  design,  less seal  smoother f o r c e t r a n s i t i o n s a l s o l e s s e n  sudden l o a d s on the pump s u p e r s t r u c t u r e , working l i f e and  with  extending  the  the  improving s t r u c t u r e s t a b i l i t y .  VALVE CLOSURE DELAYS  The evident  opening and c l o s i n g of the p i s t o n and  foot valves  from the t e n s i o n o r compression f o r c e s measured a t  the p i s t o n rod.  Examination o f the time and  t r a v e l l e d by the p i s t o n from the beginning t o the b e g i n n i n g  distance  of a stroke  o f a s s o c i a t e d f o r c e s , i n d i c a t e s the  i n v a l v e opening and c l o s i n g . the p r o p o r t i o n o f v o l u m e t r i c  stage  delays  This i s useful i n analyzing losses a t t r i b u t a b l e to valve  d e l a y s as opposed t o leakage p a s t the p i s t o n s e a l . The  are  p i s t o n v a l v e c l o s u r e delay,  shown by the more  h o r i z o n t a l p o r t i o n o f the f o r c e curve a t the b e g i n n i n g the s t r o k e , i s about two  of  times g r e a t e r w i t h the two-plate  57 p i s t o n than w i t h the No. 6 p i s t o n . s t r o k e l e n g t h d e l a y o f t h e two-plate  The average 1.0 cm piston valve  e f f e c t i v e l y reduces t h e s t r o k e l e n g t h used f o r pumping by 25%  i n t h e l a b o r a t o r y t e s t s and an e s t i m a t e d  tests.  8% i n t h e f i e l d  The d i f f e r e n c e between the l a b o r a t o r y and  field  t e s t s i s a r e s u l t o f the l o n g e r s t r o k e l e n g t h s o f t h e Bangladeshi  o p e r a t o r s i n the f i e l d t e s t s .  The p r o p o r t i o n of  the s t r o k e used f o r v a l v e c l o s u r e becomes s m a l l e r w i t h the longer stroke. reduced  In e i t h e r case, the v a l v e d e l a y r e s u l t s i n  d i s c h a r g e and lower v o l u m e t r i c e f f i c i e n c y .  The 0.5  cm d e l a y w i t h the No.6 p i s t o n reduces t h e useable  stroke  l e n g t h by 12.5 p e r c e n t and an estimated  i n the  4 percent  l a b o r a t o r y and f i e l d t e s t s r e s p e c t i v e l y .  Field  Tests  Standard Piston  Piston  Foot-valve  Total  8  13  21  13  17  25  40  65  12.5  40  No. 6 Piston Lab.  Tests  Standard Piston No. 6 Piston  52.5  T a b l e I I : Percent l o s s from p i s t o n and f o o t - v a l v e delays.  58 It to  s h o u l d a l s o be noted t h a t t h e looseness  t r e a d l e l e v e r connection  of the piston  often r e s u l t s i n a longer  t r e a d l e l e v e r s t r o k e l e n g t h than p i s t o n s t r o k e l e n g t h . such, t h e s t r o k e s seemed l o n g e r t o t h e o p e r a t o r than  As  those  measured. Delays i n f o o t - v a l v e c l o s i n g a r e i n d i c a t e d by t h e downward d i s t a n c e t r a v e l l e d by t h e p i s t o n b e f o r e  compressive  f o r c e s which i n d i c a t e movement o f water through t h e p i s t o n r a t h e r than through t h e f o o t - v a l v e , a r e exerted'on t h e piston.  As seen i n f i g u r e s 14 and 15, t h e d e l a y i n f o o t -  v a l v e c l o s i n g i s l a r g e , t a k i n g up as much as 1.6 cm o f stroke length.  T h i s d e l a y r e p r e s e n t s an average o f 40% o f  the s t r o k e l e n g t h i n t h e l a b o r a t o r y t e s t s and an estimated average o f 13% i n t h e f i e l d The  cumulative  tests.  e f f e c t s of valve closure delays are  given i n Table I I . As p r e v i o u s l y mentioned, t h e d i f f e r e n c e s i n o p e r a t i n g s t y l e s i n t h e f i e l d t e s t s r e s u l t i n t h e v a r i a t i o n between the l o s s e s c a l c u l a t e d from t h e l a b o r a t o r y and averaged t e s t values.  field  The primary cause f o r t h e d i f f e r e n c e i s t h e  t h r e e times l o n g e r average s t r o k e l e n g t h o f 13 cm f o r t h e Bangladeshi  operated  f i e l d t e s t s as opposed t o t h e 4 cm  l e n g t h f o r t h e author operated  laboratory tests.  s t r o k e l e n g t h s used by t h e Bangladeshi  The l o n g e r  farmers i n t h e f i e l d  t e s t s reduces t h e o v e r a l l e f f e c t o f v a l v e c l o s u r e d e l a y s . Although t h e percentage l o s s e s a r e not as g r e a t i n t h e f i e l d  59 t e s t s , the c l o s u r e d e l a y s s t i l l  r e p r e s e n t a major l o s s i n  the s h o r t s t r o k e s as compared t o the f u l l c y l i n d e r l e n g t h s t r o k e s o f the o r i g i n a l rope and p u l l e y system shown i n f i g u r e 3. has  The  s h i f t t o the "dheki" o p e r a t i n g system t h a t  r e s u l t e d i n the s h o r t e r s t r o k e l e n g t h s was  Bangladeshi  initiated  farmers t o i n c r e a s e o p e r a t o r comfort.  by  They  found t h a t the weight s h i f t i n g , non-knee bending s t y l e of o p e r a t i n g the "dheki" system was  more comfortable  s t e p p i n g a c t i o n o f the rope and p u l l e y system.  than the  In e i t h e r  system, the o p e r a t o r w i l l move towards or away from the pump t o a c h i e v e the most comfortable i n p u t requirement.  s t r o k e l e n g t h and power  With the non-knee bending s t y l e of the  " d h e k i " o p e r a t i o n , the changes i n s t r o k e l e n g t h are by the h i p j o i n t motion and as such the range o f length i s small.  limited  stroke  For the a n a l y s i s of the pump, i t was  assumed t h a t the s t r o k e l e n g t h i s u n l i k e l y t o i n c r e a s e beyond the extremes measured i n the f i e l d .  For the most  p a r t , the l o n g e r s t r o k e l e n g t h s i n the f i e l d t e s t s over the l a b o r a t o r y t e s t s are a r e s u l t of many hours o f pumping experience operator,  by the Bangladeshi  operators.  The  laboratory  o p e r a t i n g pumps i n Bangladesh, c o n s i s t e n t l y had  shorter stroke lengths, f u r t h e r i n d i c a t i n g that  the  d i f f e r e n c e l i e s w i t h the o p e r a t o r r a t h e r than the pump installation.  60 7.3  THE EFFECT OF WATER TABLE DEPTH ON APPLIED FORCE As t h e f o r c e a p p l i e d t o t h e p i s t o n i s t h e sum o f  providing  t h e unbalanced head t o p r o v i d e water flow,  overcoming l o s s e s , a c c e l e r a t i n g t h e water column and i n c r e a s i n g t h e p o t e n t i a l energy o f t h e t r e a d l e l e v e r , an increase  i n water t a b l e depth w i t h no i n c r e a s e  r i s e r length,  i n overall  a f f e c t s only t h e f o r c e r e q u i r e d t o c r e a t e t h e  unbalanced head needed f o r water flow.  The i n c r e a s e i n  f o r c e , as shown i n f i g u r e 16, from 230 t o 350 newtons, a d i f f e r e n c e o f 120 newtons, w i t h an i n c r e a s e 5.36  from 3.44 t o  meters r e s p e c t i v e l y , i s , f o r a l l i n t e n t s and purposes,  equal t o t h e t h e o r e t i c a l d i f f e r e n c e o f 123 newtons c a l c u l a t e d u s i n g e q u a t i o n 1 and 2 from s e c t i o n 4.3, f o r t h e same depth i n c r e a s e .  T h i s shows t h a t t h e a c c e l e r a t i o n and  head l o s s e s a r e dependent upon r i s e r l e n g t h and n o t t h e water t a b l e depth. As t h e area under t h e f o r c e displacement loop  equals  the work done, t h e i n c r e a s e  i n f o r c e w i t h an i n c r e a s e i n  water t a b l e depth, i n c r e a s e s  t h e work done p r o v i d e d t h e  stroke  7.4  l e n g t h and s t r o k e r a t e a r e c o n s t a n t .  THE EFFECT OF WATER TABLE DEPTH ON DISCHARGE AND  VOLUMETRIC EFFICIENCY The  e f f e c t o f water t a b l e depth on v o l u m e t r i c  e f f i c i e n c y was found t o be a r e d u c t i o n  of volumetric  61  e f f i c i e n c y w i t h i n c r e a s i n g depth, as shown i n f i g u r e  17.  T h i s i n d i c a t e s t h a t v a l v e and s e a l leakage, r e s p o n s i b l e f o r poor v o l u m e t r i c e f f i c i e n c y , i s a f u n c t i o n o f water t a b l e depth and thus the magnitude  o f t h e s u c t i o n below the  piston. The c u r v e s p r e s e n t e d f o r t h e f i e l d t e s t s r e p r e s e n t averaged v o l u m e t r i c e f f i c i e n c i e s from the raw t e s t  results.  The v a l u e s v a r y from 35 t o 73 p e r c e n t , w i t h averages o f 55% p e r c e n t over a range o f water t a b l e depths from 2.05 meters.  The wide v a r i a t i o n was  to  4.13  a r e s u l t o f a wide range of  62  F i g u r e 17: The e f f e c t o f water t a b l e depth on v o l u m e t r i c efficiency.  pump c o n d i t i o n s , o p e r a t i o n a l s t r o k e l e n g t h s  and c y l i n d e r  c o n d i t i o n s , r e s u l t i n g i n v a r i a t i o n s i n f o o t v a l v e and p i s t o n s e a l leakage. The l a b o r a t o r y r e s u l t s f o r t h e same c o n f i g u r a t i o n o f pump as used i n t h e f i e l d , but t e s t e d over a g r e a t e r o f water t a b l e depths, i n d i c a t e d v o l u m e t r i c ranging  from 55 t o 41 percent  respectively.  range  efficiencies  a t 1.51 t o 6.22 meters  The s m a l l r e d u c t i o n  i n volumetric  efficiency  through t h e t e s t range was p r i m a r i l y due t o i n c r e a s e d  63 leakage and p i s t o n and f o o t - v a l v e d e l a y s , as seen by t h e force-displacement  curves.  This indicates that the  v o l u m e t r i c e f f i c i e n c y c h a r a c t e r i s t i c s o f t h e pump a r e more dependent on t h e motion c h a r a c t e r i s t i c s o f t h e p i s t o n r a t h e r than an i n c r e a s e i n water t a b l e depth. The  l o n g e r average s t r o k e i n t h e f i e l d t e s t s produced  reduced l o s s e s due t o v a l v e c l o s u r e d e l a y s .  The v a r i a t i o n  i n s t r o k e l e n g t h between o p e r a t o r s a l s o caused i n c r e a s e d data spread  as t h e l o n g e r s t r o k e s decreased  the proportion  o f t h e s t r o k e taken up by v a l v e opening and c l o s i n g s .  This  e f f e c t i v e l y i n c r e a s e d t h e v o l u m e t r i c e f f i c i e n c y o f t h e pump. The  s i m i l a r i t y of the volumetric e f f i c i e n c i e s i n the  l a b o r a t o r y and f i e l d t e s t s i n d i c a t e d much g r e a t e r l o s s e s p a s t t h e p i s t o n buckets i n t h e f i e l d t e s t s as t h e p r o p o r t i o n of l o s s e s due t o v a l v e opening and c l o s i n g were l e s s the l o n g e r s t r o k e  7.5  with  length.  POWER INPUT REQUIREMENTS The  power f o r t h e T r e a d l e pump, b e i n g s u p p l i e d by human  o p e r a t o r s , v a r i e s w i t h t h e c o n d i t i o n and surroundings o f both t h e pump and o p e r a t o r .  The l a b o r a t o r y t e s t s , u s i n g t h e  same pump c o n f i g u r a t i o n as t e s t e d i n t h e f i e l d , were conducted u s i n g s h o r t e r s t r o k e s a t roughly t h e same s t r o k e r a t e , r e s u l t i n g i n lower d i s c h a r g e s .  The s h o r t e r s t r o k e  l e n g t h used i n t h e l a b o r a t o r y was a r e s u l t o f t h e pump o p e r a t i o n b e i n g c o n t r o l l e d a c c o r d i n g t o o p e r a t o r comfort, as  65 POWER INPUT (watts)  1.51  2.57  3.34  3.62  4.09  5.36  D E P T H TO WATER TABLE (meters) ^  LAB. RESULTS  ••+•- EST. FIELD RESULTS  F i g u r e 18: L a b o r a t o r y and e s t i m a t e d f i e l d power i n p u t requirements.  The l a b o r a t o r y measured and e s t i m a t e d f i e l d t e s t power requirements both i n d i c a t e t h a t t h e r e i s an upper maximum power output a b i l i t y f o r o p e r a t o r s o f t h e T r e a d l e pump. T h i s v a l u e was measured as 50 watts a t t h e pump head w i t h some v a r i a t i o n w i t h o p e r a t o r and pump i n s t a l l a t i o n . the l o s s e s r e s u l t i n g from f r i c t i o n  Adding  i n t h e s u p e r s t u c t u r e not  measured by t h e l a b o r a t o r y i n s t r u m e n t a t i o n , t h e a c t u a l f o r power i n p u t i s c l o s e r t o 55 watts.  limit  Although i t i s  p o s s i b l e t o produce much more power than t h i s over a s h o r t p e r i o d o f time, t h e o f t e n malnourished Bangladeshi o p e r a t o r ,  64 i s done by t h e Bangladeshi what was comfortable  farmer.  The d i f f e r e n c e between  t o t h e North American l a b o r a t o r y  o p e r a t o r and t h e Bangladeshi  farmer o p e r a t o r s was t h e cause  of t h e d i f f e r e n c e s i n s t r o k e l e n g t h .  Assuming t h e l o s s e s  remained constant between t h e l a b o r a t o r y t e s t s and t h e f i e l d t e s t s , t h e power i n p u t should be p r o p o r t i o n a l t o t h e discharge  i n both t e s t s .  U s i n g t h e l a b o r a t o r y d i s c h a r g e and  power i n p u t measurements, i n c l u d i n g t h e power r e q u i r e d t o r a i s e t h e t r e a d l e l e v e r estimated  by t h e amount o f work done  by t h e l e v e r d u r i n g t h e p i s t o n downstoke, e s t i m a t e s  were  made f o r t h e power i n p u t from t h e f i e l d t e s t s , shown i n f i g u r e 18, u s i n g t h e f i e l d d i s c h a r g e measurements. estimates  The  do not f u l l y take i n t o account t h e i n e f f i c i e n c i e s  o f t h e s u p e r s t r u c t u r e , which i n c l u d e t h e f r i c t i o n  at the  c e n t r a l a x l e p i v o t and a t t h e p i s t o n t o t r e a d l e l e v e r connection,  o c c u r r i n g between t h e o p e r a t o r and t h e p i s t o n s  where t h e data was c o l l e c t e d . As w i t h t h e measured l a b o r a t o r y data, t h e f i e l d power i n p u t s r i s e s h a r p l y w i t h an i n c r e a s e i n depth t o t h e water t a b l e , as a r e s u l t o f t h e i n c r e a s e d f o r c e r e q u i r e d c r e a t e the unbalanced head r e q u i r e d for.water table.  Corresponding  flow from t h e water  t o t h i s i n c r e a s i n g power requirement,  the pump d i s c h a r g e decreases due t o i n c r e a s e d l o s s e s from pipe f r i c t i o n  and leakage through t h e v a l v e s and p i s t o n  s e a l s as d e s c r i b e d i n s e c t i o n 7.4.  pumping f o r p e r i o d s o f a t l e a s t 30 minutes d u r a t i o n and a t o t a l d a i l y pumping requirement  o f t e n between 8 and 10 hours  per day, w i l l not exceed t h i s v a l u e . (EPC  The t e s t i n g by EPC  1988), which measured power i n p u t u s i n g o p e r a t o r  m e t a b o l i c measurments, s t a t e s maximum power o p e r a t o r  output  v a l u e s as 69.73 and 51.7 watts f o r pumping d u r a t i o n s o f 20 and  30 minutes r e s p e c t i v e l y , c l o s e l y agrees w i t h t h e r e s u l t s  o b t a i n e d by c a l c u l a t i o n from t h e l a b o r a t o r y and f i e l d  tests.  T h i s l i m i t o f power has i m p l i c a t i o n s t o area i r r i g a b l e from a g i v e n depth.  The area must remain above t h e minumum  found  by O r r (Orr and Islam 1988) t o be t h e minimum f o r economic v i a b i l i t y and y e t remain w i t h i n t h e power c a p a b i l i t i e s o f the o p e r a t o r . For example, t h e minimum d i s c h a r g e r e q u i r e d t o supply an average farmer's  0.24 Ha (0.65 acre) crop, w i t h a  consumptive use o f 6 mm/day, u s i n g one pump and a maximum pumping time o f 8 hours p e r day, depth t o water t a b l e s t i l l requirements  i s 28 1/min.  The maximum  a b l e t o meet t h e i r r i g a t i o n  would be 3.8 meters and would r e q u i r e a  c o n s t a n t power i n p u t o f 40 watts, u s i n g t h e l a b o r a t o r y based f i e l d e s t i m a t e s o f i n p u t power requirements discharge  and f i e l d  results.  Regions where marketing  o f t h e pump has been l e s s  s u c c e s s f u l have water t a b l e depths o f 4 meters and g r e a t e r . The d i f f i c u l t y i n m a i n t a i n i n g t h e 28 l i t r e / m i n u t e i r r i g a t i o n requirement  without exceeding  t h e power i n p u t l i m i t o f 55  67 watts a t t h e s e depths, i s f o r t h e most p a r t , t h e cause f o r the poor  sales.  7.6 PUMP AGE EFFECTS ON DISCHARGE AND VOLUMETRIC EFFICIENCY The age o f t h e t r e a d l e pumps f i e l d t e s t e d i n Bangladesh had l i t t l e e f f e c t on t h e d i s c h a r g e and v o l u m e t r i c e f f i c i e n c y c h a r a c t e r i s t i c s measured as shown i n f i g u r e 19. VOLUMETRIC EFFICIENCY  10  • *  DISCHARGE (L/min)  20 30 PUMP AGE (months)  40  DISCHARGE  -f-  BEST FIT DISCH.CURVE  VOL. EFFICIENCY  -B-  BEST FIT V.E. CURVE  F i g u r e 19: E f f e c t o f pump age on v o l u m e t r i c e f f i c i e n c y and d i s c h a r g e from f i e l d  tests.  68 The  l a r g e v a r i a t i o n s i n owner maintenance and care o f  the pumps observed and t e s t e d , overshadowed any long term e f f e c t s from age as can be seen by t h e l a r g e degree o f s c a t t e r i n the data.  V a r i a t i o n s o f component wear were  w i d e l y observed, w i t h some pumps r e q u i r i n g replacement p i s t o n buckets and f o o t - v a l v e  f l a p s a f t e r two o r t h r e e  months and o t h e r s not u n t i l a f t e r 2 o r 3 y e a r s .  Major wear  i n t h e s t e e l pump body was c o m p a r a t i v e l y minimal by v i s u a l i n s p e c t i o n compared t o t h e obvious wear o f t h e cup s e a l s and valves.  7.7 EFFECTS OF PUMP BODY CONFIGURATION ON VOLUMETRIC EFFICIENCY, POWER REQUIREMENTS AND DISCHARGES E f f e c t s from a l t e r n a t e pump c o n f i g u r a t i o n s , t h e combinations o f t h e two p i s t o n and two pump body types, most e v i d e n t volumetric  i n the laboratory  results f o r force  were  inputs,  e f f i c i e n c i e s , d i s c h a r g e s and i n p u t power  requirements as shown i n f i g u r e 20. The  volumetric  e f f i c i e n c y i s much lower when t h e No. 6  p i s t o n i s used as compared t o t h e standard two p l a t e p i s t o n , w i t h e i t h e r pump body a t t h e same water t a b l e depth. i s a t t r i b u t a b l e t o poor s e a l i n g o f t h e poppet v a l v e No. 6 p i s t o n .  This i n the  The r e s u l t o f t h i s leakage i s a l o s s o f  s u c t i o n c a p a b i l i t y and t h e p a r t i a l l y t h e lower d i s c h a r g e s i n d i c a t e d i n f i g u r e 20.  69  1  DISCHARGE (L/mln)  VOLUMETRIC EFF'Y  T 30  0.  0.9  -- 25  0.8 -0.7 --  20  0.6 0.5 --  15  0.4 --- 10  0.3 -0.2 --  -- 5  D.l -0 2  +  +  3  4  5  WATER TABLE DEPTH (maters) — -  BOX:5  BOX; 6  HOX:S  -0-- BOX: 6  "A-  YiSTND  "B-  Y:N0.6  YiSTND  -X-  Y:N0.6  F i g u r e 20: E f f e c t o f pump c o n f i g u r a t i o n on l a b o r a t o r y measured v o l u m e t r i c  The  e f f i c i e n c y and d i s c h a r g e .  e f f e c t s o f pump body type a r e s i m i l a r t o those o f  the p i s t o n s , but t h e reasons f o r t h e p o o r e r performance o f the Y - s t y l e pump a r e l e s s obvious. the v o l u m e t r i c  As shown i n f i g u r e 2 0 ,  e f f i c i e n c i e s and d i s c h a r g e s  f o r the Y-style  pump a r e a l l lower than f o r a s i m i l a r l y c o n f i g u r e d box manifold  pump.  The lower v o l u m e t r i c  e f f i c i e n c y when u s i n g  the same s e t o f p i s t o n s i n each c o n f i g u r a t i o n , g i v e s a c l e a r i n d i c a t i o n t h a t t h e f o o t - v a l v e on t h e Y - s t y l e pump t e s t e d i n the l a b o r a t o r y was o p e r a t i n g p o o r l y ,  as no o t h e r change was  70  made which c o u l d a f f e c t leakage l o s s e s .  As a r e s u l t ,  can be s a i d about t h e e f f e c t s o f t h e Y - s t y l e T r e a d l e except t h a t any i n c r e a s e s manifold  design,  be overshadowed  little pump,  i n performance a t t r i b u t a b l e t o t h e  e i t h e r Y - s t y l e o r box, must be minimal t o by v a r i a t i o n s i n f o o t - v a l v e performance.  The a l t e r n a t e pump c o n f i g u r a t i o n s were not f i e l d  tested  so no comparison i s p o s s i b l e t o t h e performance t h e pumps would have i n Bangladesh.  Given t h e poor l a b o r a t o r y t e s t  r e s u l t s , an assumption o f s i m i l a r f i e l d performance would be r e a s o n a b l e g i v e n t h e c l o s e agreement  i n l a b o r a t o r y and f i e l d  r e s u l t s o f t h e c o n f i g u r a t i o n w i d e l y used i n Bangladesh, t h e box m a n i f o l d  and two-plate p i s t o n .  8 DISCUSSION 8.1 VALIDATION OF THEORETICAL MODEL BY LABORATORY TESTS The g o v e r n i n g equations p r e s e n t e d i n s e c t i o n 4.3 produced a f o r c e displacement curve t h a t compares c l o s e l y w i t h t h e l a b o r a t o r y r e s u l t s as shown i n f i g u r e 21,  F i g u r e 21: Comparison o f c a l c u l a t e d and l a b o r a t o r y results.  which i s f o r a model w i t h t h e box-type m a n i f o l d u s i n g t h e standard  two-plate p i s t o n .  T r e a d l e pump  Values f o r mechanical  f r i c t i o n and p i s t o n motion c h a r a c t e r i s t i c s used i n t h e c a l c u l a t i o n s where taken from t h e l a b o r a t o r y t e s t data, not from t h e d e r i v e d motion equations.  The c l o s e agreement o f  the l a b o r a t o r y and c a l c u l a t e d f o r c e curves shown i n f i g u r e 21 i s l a r g e l y due t o u s i n g measured p i s t o n motion r a t h e r than t h e t h e o r e t i c a l v a l u e s . values  T h i s i s because t h e measured  account f o r i r r e g u l a r i t i e s p r e s e n t  i n the laboratory  t e s t s t h a t would not be accounted f o r i n t h e t h e o r e t i c a l motion v a l u e s . The  l a b o r a t o r y and t h e o r e t i c a l r e s u l t s f o r t h e o t h e r  t h r e e pump c o n f i g u r a t i o n s a r e a l s o i n c l o s e agreement.  This  i s t o be expected because t h e a l t e r a t i o n s from t h e standard c o n f i g u r a t i o n a r e p r i m a r i l y i n v a l v e d e l a y and leakage parameters, which were d e r i v e d from t h e l a b o r a t o r y  data.  8.2 COMPARISON OF LABORATORY AND FIELD TEST RESULTS The  inconsistency of f i e l d operators  and pumps made t h e  comparison between l a b o r a t o r y and f i e l d t e s t r e s u l t s difficult.  Averaged f i e l d r e s u l t s , used f o r comparison a t  0.2 meter increments o f water t a b l e depth, showed t h a t t h e s h o r t e r s t r o k e l e n g t h s and t h e equal  o r slower s t r o k e  used i n t h e l a b o r a t o r y , as an e s t i m a t i o n o f how a B a n g l a d e s h i farmer would operate t h e pump over l o n g  rates  d u r a t i o n s , produced lower d i s c h a r g e configurations.  than f o r s i m i l a r f i e l d  The s h o r t e r s t r o k e l e n g t h s used i n the  l a b o r a t o r y t e s t s were a r e s u l t o f what was comfortable f o r the o p e r a t o r .  The Bangladeshi farmers a r e more  comfortable  w i t h t h e s l i g h t l y l o n g e r s t r o k e l e n g t h but they s t i l l the much s h o r t e r s t r o k e o f the "dheki"  style  prefer  superstructure  t o t h e f u l l l e n g t h s t r o k e s of t h e r o p e - p u l l e y superstructure.  The f i e l d t e s t o p e r a t o r s  pumped w i t h  longer  s t r o k e s and o f t e n a f a s t e r s t r o k e r a t e s than were assumed for  the l a b o r a t o r y t e s t s , but tended t o pump f o r s h o r t e r  d u r a t i o n s , about 1/2 hour r a t h e r than continuous pumping, as they reached the l i m i t o f t h e i r power output c a p a b i l i t i e s . The s h o r t e r pumping d u r a t i o n , t h e m o t i v a t i o n o f i r r i g a t i n g t h e s o l e source o f income f o r t h e f a m i l y group, and  a v a i l a b i l i t y and a f f o r d a b i l i t y o f food and medicine may  r e s u l t i n higher  power i n p u t s than a n t i c i p a t e d from t h e  laboratory tests. The v o l u m e t r i c  e f f i c i e n c y r e s u l t s were w i d e l y  spread i n  the f i e l d data but the averaged r e s u l t s agreed c l o s e l y w i t h the l a b o r a t o r y data.  T h i s c l o s e agreement i n v o l u m e t r i c  e f f i c i e n c y and thus l o s s e s , allowed  f o r the c a l c u l a t i o n of  i n p u t power f o r t h e f i e l d t e s t s t o be s c a l e d from t h e d i s c h a r g e measurements from t h e l a b o r a t o r y t e s t s . The c l o s e agreement between t h e t h e o r e t i c a l c a l c u l a t i o n s and t h e l a b o r a t o r y r e s u l t s , and t h e s i m i l a r values  f o r volumetric  e f f i c i e n c y i n the l a b o r a t o r y and  field  74 r e s u l t s , provide  a b a s i s f o r design  alterations valid for  f i e l d a p p l i c a t i o n based on t h e t h e o r e t i c a l and l a b o r a t o r y results.  8.3 IMPLICATIONS OF THE RESULTS ON PUMP RE-DESIGN Over t h e p a s t increase  few y e a r s ,  since the s t a r t of the rapid  i n p o p u l a r i t y and s a l e s o f t h e T r e a d l e pump, many  s u g g e s t i o n s have been made t o a l t e r t h e pump d e s i g n .  Part  of t h e purpose o f t e s t i n g t h e T r e a d l e pump was t o form a b a s i s f o r e v a l u a t i n g these suggestions. design  Some o f pump r e -  s u g g e s t i o n s have i n c l u d e d changes t o :  1. Pump body m a t e r i a l s ,  i n c l u d i n g PVC, c o n c r e t e ,  fiberglass,  j u t e g l a s s and c a s t i r o n . 2.  Piston configurations,  i n c l u d i n g r e t a i n i n g t h e standard  two-plate p i s t o n o r u s i n g t h e No.6 p i s t o n t e s t e d . 3.  C y l i n d e r s i z e , w i t h 76 mm  and  51 mm  4.  C y l i n d e r l e n g t h , such as a 203 mm  inch)  (3 i n c h ) , 64 mm  (2 1/2 inch)  (2 inch) diameters suggested. (8 inch)  c y l i n d e r t o r e p l a c e t h e c u r r e n t 356 mm  o r 254 mm (10  (14 inch)  length. 5.  The s t y l e o f pump t o r i s e r j u n c t i o n , w i t h t h e o r i g i n a l  box-style  and t h e Y - s t y l e suggested.  The t e s t r e s u l t s have i n d i c a t e d t h a t , i n t h e case o f a l t e r i n g pump m a t e r i a l , t h e f r i c t i o n f o r c e o f t h e s e a l a g a i n s t t h e c y l i n d e r would change m a r g i n a l l y m a t e r i a l change, as t h e p r e s s u r e  with a c y l i n d e r  of the seal against the  75 c y l i n d e r would remain c o n s t a n t and t h e c o e f f i c i e n t o f f r i c t i o n between t h e s e a l and any o f t h e m a t e r i a l s l i s t e d does not v a r y g r e a t l y .  With t h e marginal scope f o r  improvement from a h y d r a u l i c s view, t h e r e a s o n i n g f o r a change i n pump m a t e r i a l s must r a t h e r be based upon economic or manufacturing b e n e f i t s .  In b r i e f , g i v e n t h e c u r r e n t  development s t r a t e g y t o promote s m a l l s c a l e d e c e n t r a l i z e d manufacturing o f t r e a d l e pumps i n Bangladesh  and t h e more  pragmatic reasons i n c l u d i n g t h e a v a i l a b i l i t y o f machine t o o l s f o r working w i t h s t e e l and t h e a v a i l a b i l i t y , wide acceptance and r e - s a l e v a l u e o f s t e e l p r o d u c t s throughout Bangladesh,  t h e use o f s t e e l f o r t h e t r e a d l e pump p r o v i d e s  t h e b e s t s o l u t i o n i n terms o f t h e development and economic c r i t e r i o n a t t h e p r e s e n t time.  The use o f s t e e l  reduces t h e r e l i a n c e on new, more expensive  also  imported  m a t e r i a l s , p r o d u c t s and c e n t r a l i z e d p r o d u c t i o n technology r e q u i r e d f o r many o f t h e a l t e r n a t e m a t e r i a l s . In t h e case o f p i s t o n d e s i g n a l t e r a t i o n , both o f t h e two p i s t o n c o n f i g u r a t i o n s t e s t e d , t h e two-plate p i s t o n and the No. 6 p i s t o n , have advantages.  The two-plate p i s t o n i s  more w i d e l y used, e a s i l y f i x e d and p r o v i d e s b e t t e r p i s t o n v a l v e s e a l i n g than t h e No. 6 p i s t o n , which b e n e f i t s  from  wide a v a i l a b i l i t y ,  s h o r t e r v a l v e d e l a y s and a n o n - r u s t i n g  pPVC c o n s t r u c t i o n .  O p t i m a l l y , a combination o f t h e s m a l l  c l o s i n g time o f t h e No.6 and p o s i t i v e s e a l i n g o f t h e two p l a t e d e s i g n should be used.  76 In t h e case o f the c y l i n d e r s i z e , d i s c h a r g e and power i n p u t requirements are p r i m a r i l y a f f e c t e d by any  alteration.  A decrease i n c y l i n d e r diameter would reduce the d i s c h a r g e i n comparison  t o the p r e s e n t 89 mm  (3.5 inch) d e s i g n .  This  would a l l o w use o f the pump t o a g r e a t e r depth without exceeding a power i n p u t l i m i t a t i o n of 55 watts, which corresponds t o a h y d r a u l i c output o f 25.3 use.  watts, i n normal  As a r u l e of thumb, an i n c r e a s e i n water t a b l e depth  a c c e s s i b i l i t y o f 1.4  meters p e r 13 mm  i n c y l i n d e r diameter.  The 13 mm  (1/2 inch) r e d u c t i o n  r e d u c t i o n i n diameter i s  accompanied by a 27% decrease i n d i s c h a r g e , assuming l o s s e s are t h e same as those o c c u r r i n g i n the c u r r e n t pump d e s i g n , w i t h the 55 watt i n p u t l i m i t a t i o n . For example, u s i n g a d i s c h a r g e requirement o f 25 L/min as the minimum t o meet i r r i g a t i o n requirements, the maximum depth of a p p l i c a t i o n f o r a 102 mm T r e a d l e pump would be 3.86 The 89 mm  (4 inch) c y l i n d e r  meters,  (3.5 inch) t r e a d l e was  diameter  l i m i t e d by power i n p u t .  found t o have a maximum  water t a b l e depth a p p l i c a t i o n of 4.09  meters,  l i m i t e d by  d i s c h a r g e below the requirement and near the l i m i t of power input.  A 76 mm  (3 inch) T r e a d l e pump would have a maximum  a p p l i c a t i o n depth of 5.88  meters,  t h e i r r i g a t i o n requirement. would have a maximum o f 4.3 below the requirement.  l i m i t e d by d i s c h a r g e below  A 64 mm meters,  (2.5 inch) T r e a d l e l i m i t e d by d i s c h a r g e  77 From t h e s e c a l c u l a t i o n s , t h e optimum c y l i n d e r diameter, assuming o p e r a t i n g  l o s s e s , power i n p u t s and pumping  o p e r a t i n g parameters remain unchanged from those measured i n the f i e l d and l a b o r a t o r y t e s t i n g , i s 76 mm  (3 i n c h e s ) .  This  s i z e would a l l o w T r e a d l e pump usage t o a maximum water t a b l e depth and remain w i t h i n t h e l i m i t s o f power i n p u t and i r r i g a t i o n requirements.  Any i n c r e a s e i n e f f i c i e n c y would  i n c r e a s e t h e power output f o r t h e 55 watt l i m i t o f power i n p u t and i n c r e a s e t h e optimum c y l i n d e r s i z e w i t h i n t h e 6 meter water t a b l e  limit.  In t h e case o f c y l i n d e r l e n g t h , a r e d u c t i o n would reduce t h e pump c o s t by about 8 Taka (0.32 CAD) p e r centimetre.  Although on average o n l y 140 mm o f t h e 356 mm  (14 inch) c y l i n d e r i s used d u r i n g t h e pump s t r o k e , t h e p o r t i o n o f c y l i n d e r used v a r i e s between i n s t a l l a t i o n s . F i e l d t r i a l s conducted by IDE w i t h t h e 305 mm  (12 inch)  c y l i n d e r pump, found t h a t t h e r e d u c t i o n i n l e n g t h g r e a t e r accuracy installation.  required  o f s u p e r s t r u c t u r e placement a t  T h i s reduced pump p o p u l a r i t y due t o t h e l i m i t  of i n s t a l l a t i o n v a r i a t i o n p o s s i b l e . In t h e case o f t h e j u n c t i o n s t y l e , from t h e c a l c u l a t e d results,  i t was determined t h a t t h e power l o s s e s r e s u l t i n g  from t u r b u l e n c e 12%  through t h e m a n i f o l d  account f o r l e s s than  o f t h e t o t a l head l o s s e s , not i n c l u d i n g v a l v e d e l a y and  leakage l o s s e s , a t maximum water v e l o c i t y i n t h e p i s t o n and riser,  a t a head o f 3.34 meters. The a l t e r a t i o n i n type o f  78 j u n c t i o n manifold  from the b o x - s t y l e  t o the Y - s t y l e s u f f e r s  from i n c r e a s e d manufacturing complexity and o r no s a v i n g s  from reduced l o s s e s .  The  cost with  b e n e f i t from  little the  smoother j u n c t i o n would reduce s u c t i o n head requirements by 0.03  meters a t maximum flow.  reduction  This represents  i n h y d r a u l i c l o s s e s but  a  6.4%  i s o n l y 1% of the  head l o s s e s i n the whole system, i n c l u d i n g v a l v e and l o s s e s , and  i s not worth the i n c r e a s e i n c o s t  manufacturing  difficulty.  and  total leakage  10 CONCLUSION In c o n c l u s i o n , t h e T r e a d l e pump performance can be b e s t improved by d e s i g n a l t e r a t i o n s t o t h e p i s t o n and f o o t - v a l v e s as i n d i c a t e d by t h e low d i s c h a r g e s and v o l u m e t r i c e f f i c i e n c i e s measured i n t h e l a b o r a t o r y and f i e l d t e s t s , and by a r e d u c t i o n i n c y l i n d e r diameter t o permit pump use i n areas w i t h g r e a t e r water t a b l e depths. The  comparatively  s m a l l l o s s e s caused by t u r b u l e n c e and  f r i c t i o n i n d i c a t e t h a t a l t e r a t i o n s t o t h e pump m a t e r i a l and c o n f i g u r a t i o n , as shown i n t h e l a b o r a t o r y and t h e o r e t i c a l r e s u l t s , a r e not warranted on t h e b a s i s o f improved pump performance, b u t must be d e c i d e d from economic and development s t r a t e g y b e n e f i t s . The primary  problems i d e n t i f i e d from t h e l a b o r a t o r y and  f i e l d t e s t i n g o f t h e "dheki" s t y l e T r e a d l e pump i n s t a l l a t i o n s were t h e leakage through t h e p i s t o n and f o o t v a l v e s and t h e l a r g e v a l v e c l o s u r e d e l a y times.  Although  the l o n g e r s t r o k e l e n g t h s o f t h e f i e l d t e s t s reduced t h e e f f e c t o f t h e v a l v e d e l a y s , even a t t h e maximum  comfortable  s t r o k e l e n g t h s recorded t h e minimum l o s s r e s u l t i n g from v a l v e d e l a y s i s 17%.  F o r example, i f both t h e p i s t o n and  f o o t - v a l v e c l o s u r e d e l a y times where halved, t h e decrease i n leakage  represents a p o t e n t i a l increase i n volumetric 79  80 e f f i c i e n c y o f 46%, r e s u l t i n g i n i n c r e a s e d d i s c h a r g e and use t o g r e a t e r water t a b l e depths. The water t a b l e depth t o which t h e T r e a d l e pump i s u s a b l e i s l i m i t e d by e i t h e r i n s u f f i c i e n t d i s c h a r g e o r l a r g e i n p u t power requirements, depending upon c y l i n d e r s i z e and depth t o water t a b l e .  The c u r r e n t 89 mm  (3.5 inch) c y l i n d e r  diameter pump i s l i m i t e d t o a water t a b l e depth o f 4 meters, due t o t h e s u s t a i n a b l e power i n p u t l i m i t o f 55 watts i n d i c a t e d by t h e f i e l d and l a b o r a t o r y r e s u l t s .  The  d i f f i c u l t y o f s e l l i n g t h e pumps i n r e g i o n s w i t h water t a b l e depths deeper than 4 meters and t h e EPC t e s t r e s u l t s i n d i c a t e a water t a b l e depth l i m i t o f 4 meters. i n c y l i n d e r s i z e t o 76 mm  also  A reduction  (3 inch) would i n c r e a s e t h e water  t a b l e depths a c c e s s i b l e t o t h e T r e a d l e pump w i t h i n t h e l i m i t a t i o n s o f power i n p u t and m a i n t a i n enough d i s c h a r g e t o meet i r r i g a t i o n requirements.  The 76 mm pump would be most  s u i t a b l e f o r water t a b l e depths i n t h e 4 t o 5.5 meter range, t o a s s u r e t h a t t h e power i n p u t r e q u i r e d does n o t exceed 55 watts.  Any f u r t h e r r e d u c t i o n i n diameter p a s t 76 mm would  reduce t h e d i s c h a r g e below t h e i r r i g a t i o n requirements f o r t h e 0.24 Ha (0.6 acre) minimum i r r i g a t e d a r e a r e q u i r e d f o r pump repayment.  The use o f t h e w i d e l y a v a i l a b l e 89 mm (3.5  inch) pPVC p i s t o n cup s e a l , manufactured f o r use i n t h e u b i q u i t o u s No.6 pump, and t h e poor a v a i l a b i l i t y o f t h e 76 mm (3 inch) pPVC s e a l reduces t h e d e s i r a b i l i t y o f t h e 76 mm  81 pump a t t h e p r e s e n t time, but more work i n manufacturing a l t e r n a t i v e s may y i e l d more o p t i o n s . O v e r a l l , t h e study o f t h e p i s t o n f o r c e c h a r a c t e r i s t i c s and t h e use o f v a r i a t i o n s between f i e l d and l a b o r a t o r y r e s u l t s t o a n a l y z e t h e pump d e s i g n , c l e a r l y shows t h e b e n e f i t s o f t h e combined use o f l a b o r a t o r y , a n a l y t i c a l and field  r e s u l t s as t h e b a s i s f o r d e s i g n a l t e r a t i o n s .  The  study a l s o i n d i c a t e d t h e s t r e n g t h o f t h e d e s i g n and t h e i n n o v a t i o n by t h e a i d workers who o r i g i n a l l y developed t h e T r e a d l e pump, as v e r y l i t t l e a l t e r a t i o n i s r e q u i r e d t o o p t i m i z e t h e o p e r a t i o n o f t h e T r e a d l e pump.  LIST OF REFERENCES A l l i s o n , Stephen V. 1986. Handpump I r r i g a t i o n i n Bangladesh. Vancouver: I n t e r n a t i o n a l Development E n t e r p r i s e s Barnes, Gunnar. 1985. The Development o f a Manual I r r i g a t i o n Device: The Twin T r e a d l e Pump, M a n i l l a , P h i l i p p i n e s : I n t e r n a t i o n a l R i c e Research I n s t i t u t e . Photocopied. Barnes, Gunnar. 1981. Low Cost I r r i g a t i o n ( A g r i c u l t u r a l Programme o f RDRS). A s s o c i a t i o n o f Development Agencies i n Bangladesh News. M a r c h / A p r i l . Baumann, E r i c h and R i c h a r d J . F u l l e r . 1984. Manual I r r i g a t i o n i n Bangladesh. Dhaka: Swiss Development Cooperation. Bos, M.G., ed. 1976. Discharge Measurement S t r u c t u r e s . D e l h i : Oxford & IBH P u b l i s h i n g Co.  New  Bureau o f Research T e s t i n g and C o n s u l t a t i o n . 1986. L a b o r a t o r y T e s t i n g o f T r e a d l e Pump. Dhaka: Bangladesh U n i v e r s i t y o f E n g i n e e r i n g and Technology Consumers' A s s o c i a t i o n T e s t i n g and Research L a b o r a t o r i e s , R u r a l Water Supply Handpumps P r o j e c t . L a b o r a t o r y T e s t i n g o f Handpumps f o r Developing C o u n t r i e s . World Bank T e c h n i c a l Report No. 19. E n g i n e e r i n g and P l a n n i n g C o n s u l t a n t s L t d . 1988. T e s t i n g o f Handpumps under IDA A s s i s t e d HTW P r o j e c t ( C r e d i t 1140-BD). Dhaka: Bangladesh R u r a l Development Board Gibson, A.H. 1925. H y d r a u l i c s and i t s A p p l i c a t i o n s . 4th ed. New York: D. Van Nostrand Company Inc. G i s s e l q u i s t , David, ed. 1985. Report on BARC Sponsored Course on: Manual and Animal Powered Pumps f o r I r r i g a t i o n . Dhaka: Bangladesh A g r i c u l t u r a l Research C o u n c i l . Hahn, Robert. 1984. Handpump T e s t i n g and Development. P a r t 4, The F i r s t Year - R e s u l t s o f Completed and Ongoing T e s t s . Stockholm: Lund I n s t i t u t e o f Technology.  82  83 Hyde, C h a r l o t t e . 1987. A Mathematical M o d e l l i n g S i m u l a t i o n of Rower Pump Performance. B.A.Sc. t h e s i s , U n i v e r s i t y o f B r i t i s h Columbia. I n t e r n a t i o n a l Development E n t e r p r i s e s . 1988. Annual Report. Dhaka: I n t e r n a t i o n a l Development E n t e r p r i s e s . . 1988. Pump s a l e s f i g u r e s . Dhaka: I n t e r n a t i o n a l Development E n t e r p r i s e s . T y p e w r i t t e n . K r i s t a l , Frank A. and F.A. Annett. 1940. Pumps: Types. S e l e c t i o n , O p e r a t i o n , and Maintenance. New York: McGraw-Hill Book Company I n c . Manual Pump Group. 1987. Long-range S t r a t e g i c I s s u e s . Dhaka: Manual Pump Group. T y p e w r i t t e n . . 1988. Annual Report. Dhaka: I n t e r n a t i o n a l Development E n t e r p r i s e s . . 1988. Bangladesh Handtubewells I I P r o j e c t . Recommendations o f t h e Manual Pump Group. Dhaka: Manual Pump Group. Massey, B.S. 1968. Mechanics o f F l u i d s . London: D. Van Nostrand Company L t d . Orr, A l a s t a i r and A.S.M. N a z r u l Islam. 1988. The S o c i o Economic Impact o f t h e T r e a d l e Pump. Dhaka: Bangladesh R i c e Research I n s t i t u t e . Rangpur D i n a j p u r R e h a b i l i t a t i o n S e r v i c e . 1983. I r r i g a t i o n Manual. R e v i s e d ed. Rangpur: RDRS. . 1984. Lutheran World S e r v i c e Bangladesh Annual Report. Dhaka: RDRS. . 1984. Twin T r e a d l e Pump and D r i n k i n g Pump Manufacturer's Guide. R e v i s e d ed., Dhaka: RDRS. . 1985. Lutheran World S e r v i c e Bangladesh Annual Report. Dhaka: RDRS. Roberson, John A. and C l a y t o n T. Crowe. 1985. E n g i n e e r i n g F l u i d Mechanics. 3rd Ed. Boston: Houghton M i f f l i n Company. Spare, Dan and Doug P r i t c h a r d . 1981. Three Hand Pumps Tested A g a i n s t Tubewell C o n d i t i o n s . Dhaka: Mennonite C e n t r a l Committee.  84 S t i c k n e y , R.E., C. A b r i n a , R.L. Bacalocos, J.A. Damian, R. Domingo, B.C. Gonzalo, V.N. Piamonte, Q. deSagun and I . V e n t u r a . 1987. Human-Powered Pump f o r L o w - l i f t I r r i g a t i o n . M a n i l a : I n t e r n a t i o n a l R i c e Research I n s t i t u t e . The World Bank. 1981. Bangladesh Hand Tubewells P r o j e c t S t a f f A p p r a i s a l Report. 3280-BD. The World H e a l t h O r g a n i z a t i o n I n t e r n a t i o n a l Reference Centre f o r Community Water Supply. 1977. Handpumps f o r use i n D r i n k i n g Water S u p p l i e s i n Developing C o u n t r i e s . The Hague: The World H e a l t h O r g a n i z a t i o n . Todd, David K. 1959. Ground Water Hydrology. New Wiley and Sons Inc.  York: John  U n i t e d N a t i o n s . U n i t e d N a t i o n s Development Programme. Ground Water Survey - The H y d r o g e o l o g i c C o n d i t i o n s o f Bangladesh. U.S. Bureau o f Reclamation. 1975. Water Measurement 2nd ed. Denver.  1982.  Manual.  WHO. 1977. See The World H e a l t h O r g a n i z a t i o n I n t e r n a t i o n a l Reference Center f o r Community Water Supply. 1977. Yaw, Goh S i n g . 1985. L a b o r a t o r y and F i e l d T e s t i n g o f Handpumps. Ottawa: I n t e r n a t i o n a l Development Research C o u n c i l . IDRC-TS51e.  APPENDIX  1: AVERAGED F I E L D TEST DATA  T E S T S CONDUCTED IN THE JAMALPUR  :ST #  AND KUSHTIA REGIONS OF BANGLADESH  VOL. STROKE PUMP W. T. STROKE OPERATOR AGE DEPTH LENGTH DISCHARGE EFF'Y RATE AGE WEIGHT (m> (/mi n) (yrs) (cm) (1/min) (lbs) (yrs)  POWER OUTPUT (watts)  21 42 11 16 17 19 18 22 39 32 41 13 40 43  27 40 28 18 25 30 25 31 25 18 18 22 40 37  125 110 130 90 150 150 95 100 100 95 90 120 130 125  1 1 1 12 12 12 12 12 2 24 2 12 1 3  2.05 2.20 2.23 2.29 2.29 2.37 2.47 2.59 2.73 2. 78 2.79 2.86 2.88 2.97  12.32 16.06 9.57 13.75 9.02 11.11 15.62 9.79 14.85 15. 73 12.98 12.54 18.92 11.99  39. 22 33. 12 36.59 30. 30 23.32 35. 35 27.27 37. 15 43.83 41.93 45.00 40. 82 22.52 39.22  0.66 0.35 0.73 0.44 0. 63 0.72 0.38 0.63 0.54 0.52 0.61 0.60 0. 36 0.55  39.02 47.51 42.26 40. 61 32.95 35.76 36. 55 48.48 44. 42 41.55 46.00 43.67 26.31 28.04  13. 14 11.91 13.34 11. 35 8. 73 13.70 11.01 15. 73 19.56 19.06 20.53 19. 09 10.61 19.04  35 9 10 36 37 27 29 33 31  50 40 25 18 30 28 14 25 35  120 125 150 __. 100 120 126 80 130 125  12 2 2 2 2 12 24 12 36  3. 13 3. 25 3. 25 3. 56 3. 61 3. 73 3. 83 3. 85 3. 97  11.66 15.73 8.47 13.97 13.64 6.27 12.76 10. 12 9. 13  29.51 60.89 32.97 39.60 46.23 23.96 28.57 27.86 36.92  0.62 0.51 0.67 0.57 0.58 0.57 0.45 0.51 0.70  33.05 61.33 46.81 39.80 46.85 54.25 40.00 43. 10 46.34  15. 10 32. 35 17.52 23.05 27.29 14.61 17.89 17.54 23.97  28 23 24 25 26  23 24 25 45 25  115 110 150 110 150  36 36 36 3 3  4. 01 4. 13 4. 13 4. 28 4. 28  6.82 16. 28 9.24 5.94 5.72  27. 19 43.23 25. 17 24. 19 22.73  0.46 0.54 0.51 0.86 0.89  70.33 39. 77 43.09 38. 13 36. 06  17.83 29. 19 16.99 16. 93 15.90  85  APPENDIX 2: AVERAGED LABORATORY DATA -TESTS CONDUCTED AT THE UNIVERSITY  DF BRITISH COLUMBIA, CANADA  NOTE: THE FIRST TWO DIGITS OF THE TEST CODE INDICATE CONFIGURATION 01:BOX MANIFOLD, 2-PLATE PISTON 02:BOX MANIFOLD, NO. 6 PISTON 03:Y-MANIFOLD, 2-PLATE PISTON 04:Y-MANIFOLD, NO. 6 PISTON  TEST CODE  POWER RATE OUTPUT (/mi n) ( w a t t s )  STROKE VOL. E F F' Y HEAD LENGTH DISCHARGE (cm) (m) (l/iiiin)  POWER POWER INPUT EPF' Y (watts)  TO1021 TO1022 TO1041 TO1042 TO1061 TO1062 TO1081 TO1082  1. 51 1. 51 3. 34 3. 34 5. 36 5. 36 6. 22 6. 22  4. 04 3.35 3.56 4.24 3. 30 1.91 4.32 4.84  25. 06 25. 04 24.07 12.36 16.63 6.27 34.54 20.85  0.68 0. 41 0. 60 0. 41 0. 58 0. 30 0. 55 0.41  73.41 73.72 45.52 57. 07 70. 20 87. 94 60. 00 41.81  6. 11 6. 15 13. 15 6.69 14.58 5.49 34. 51 21. 17  26.55 23.64 50.56 31.88 64.80 35.44 95.85 81.44  0. 23 0.26 0.26 0.21 0.23 0. 16 0.36 0.26  T02021 T02022 T02041 T02042 T02061 T02062 T02081 T02082  1. 51 1. 51 3. 34 3. 34 5. 36 5. 36 6. 22 6. 22  4.08 2.78 3.28 2. 94 2.79 3. 02 4.69 3.61  42.60 28.44 24.53 15.13 16. 14 9.03 28.70 12.21  1.08 0. 49 0.43 0. 33 0.34 0.23 0.33 0. 23  77.99 91.72 69.30 63.84 67. 73 53.50 74.00 58.30  10. 56 7.57 13.50 8.28 13.92 8.00 30. 16 12. 13  45.92 37.85 42. 19 30. 68 51.57 40. 00 115.99 86.63  0.23 0.20 0.32 0.27 0.27 0. 20 0.26 0. 14  T03021 T03041 T03061 T03081  1. 51 3. 34 5. 36 6. 22  4.57 3.68 1.88 4.21  35.54 15.77 12.97 9. 72  0. 54 0. 28 0.23 0. 17  58. 17 61.81 60. 08 54.56  8.75 8.71 11.44 9.94  29. 18 39.60 54.46 99.44  0.30 0.22 0.21 0. 10  T04021 T04022 T04041 T04042 T04061 T04062 T04081 T04082  1. 51 1. 51 3. 34 3. 34 5. 36 5. 36 6. 22 6. 22  4.94 3.72 4.49 4. 11 6.71 4.31 7.65 4.77  25.84 27. 19 15.67 19. 10 17. 15 11.44 5.80 11. 03  0. 33 0. 41 0. 21 0.27 0. 18 0. 17 0. 10 0. 17  63. 55 72. 13 65. 66 68.35 56. 14 63. 17 39. 20 55.88  6.53 6.87 8.71 10.55 15.51 9.53 5.61 10.91  40.84 42.92 67.01 70.35 129.28 105.87 93.58 121.21  0. 16 0. 16 0. 13 0. 15 0. 12 0.09 0.06 0.09  86  

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