The Performance Testing Of Treadle Pumps No-39 1993

10 Pages·1993·0.1 MB·English

DEVELOPMENT
TECHNOLOGY
UNIT

Working Paper No. 39

The Performance Testing of Treadle Pumps

October 1993

Development ‘Technology Unit
Department of Engineering. University of Warwick
Coventry C¥4 7AL UK
‘Tots 444 (0)203 523523 extn 2939 Fax: [phone] Telex: 311906 GNIVWK G
Working Paper No. 39

The Performance Testing of Treadle Pumps
by Dr. T.H. Thomas

October 1993

Abstract:
A good 2 cmp sss many wer eriteiaineludiag some that can be tse
under ‘aborecory conditions. Tie paper describes a se: of laborstory sess and
perfermance thresholds thac shaid be reached ia the. The tests mise i
efifexeeey or 19 ease Under the description of prising sess there is
‘mcluced an analysis of snc effect of uny ‘dead voluice’ of trapped aie upon the
‘muxioore suction bead af a pump durieg priming ard ducing steady operation,
Listof Variables

cross-sections! ea of evtinkler or eyciva‘em cross sectional area of diaphragm
pure callene in eycles per secs
sioral vorstant ~ 9.81 mi?
luca! iad experienced by punup = ptessave rive Use! pump! pg
HAH,

ftictioe heed loss

delivery nead = delivery pant pressure / 9
(wesid) peimirg suetioa bead

suction tead = inles por: negative pressure / ng
‘maximum pornging s:ctfoa end

piston sctoke

flow thscngh gmp in ane (1 an ~ 1000 nes)
deat ow Gif 30 leakage)

Jeakage (incloding itserna. leakages} flow
ieton power Zags jroechanica’)
input power wt uewd-es

exgonaraic aficiensy

os=put flow/tourpar tow + leakage fon) = OKO + @)
ouput hew(outpot hea + head loss} = HAH 4)
Iydzaulie exticiency = Ty % Tne
ectuicai efficiency = (WF, - Want,

pimp efficiency = opus powerfnpst powe
density of wate = 1020 besa
1. Introduction

Any gon meacle purmg mst sesisfy miny criteria, Jt must be affective’ or efficient, durable, portable,
ataynanle over a ringe of users a-d delivery aeads, easy to clean end cepeir, easy t¢ install and start
For the purpose of this paper ve will restrict our inserest to performance in tho narrow sease of
elfectiveness in use, Se. performance ther. can be measnres! sn Iaharviory toss

‘Teead‘e pamps ure human operated. Tre amourt of seater that can 2e pumped depends oa the putep’s
efficiency, on the tox head znd on the effet ad physique Of the operator, 1k ss not practical to replace
hanian operat for testing purposes by calibrated motors or engiees, so any test erocedure masc
accem:nodate the vaviahility OF & person as # power source, Ie¥eed the extent 20 which the pump
fatches the aperetar (allowing 2imn cr cer to deliver power with the least frigne} is an importaae
perforaance paranvets

Hurmac-powered acemps ate not ased consinually or very steady. Trey start and stop. Ber test
pEEpOseS we uscally casmnguesh between two Paases of use

2) Sursup ar prming! when 8 pump is fist applied to anew site
by Steady pomping,

‘Trere sa varsicion from the Grgt phase 20 the sevead wareh by take as Ite as 9 soveads of es =1uch

a6 1D inizszes. Dosing this sexcing-divwr: pesiod eather pistons may swel. 2 eehieve better seaceg,

residue! cit nay be wasced cu: of piss. Libeieating oll may spread to reach Tabzing gars, Howeves

he tsnsition Yas i}-delined boucdries sad itis aormélly aleguite to simplify hebaviour inte just the

(oro phases atrendy oventoxed,

ven. eenth

Driening takes 2 cestain time, whick terminates whee the puarp output has reacted (fo:
say 95% ofits fine] or steady State value.

2, Beplormance Measures

These are many pousirie performace measures, some ef a global nature anc some describing the
effectiveness of patticucar pump varnpanents. Comnmor msasutes ae

Output floseate - for a defined (typical > operator a¢ various total headle and various suction heads. A
Convenient ropreseacatan is «9 plot fowiete @ versus told! head 7 for exch of several suction Leads
ty spanning from 0 co (sey) 8 mowers, Cleary #7 mast not 32 ‘e38 thar. H,, ‘The vieaness of “Es
measure :s the vanabtty of spereuecs. However by asing an operator of defined physique (eg. healt,
sage, sex and weight) -n a detined duty (ep. a zyc%e of 1 minutes treadlling followed by S annutes rest
smainceined or 1 hour). this variably can he Tssited, Chnput Aowzate isan easy sieasare 9 iaterPret
sand espeen. ly usefv wen comparing diferent purngs tested by the sims operat

Sucton bec - this is tbe cmaxiaen: dep from: which che pump ean suck water. There 's a absoluze
limit of about 10 =reteis on is deptt at 20°C at sex level (gsszmieg exmospherie presseze is 1000
imbsc) nick dcinishes by avout 10% for excl: Klneneter shove sew level Yn ntaetivesvtion. deads are
sully much lesa chan 10 meters, We ceed 10 distingsish bewveen rwo solutions. 1, ~ unaided
prining suction Head. is the tnaxicoamn depth from swbich some water cau be vaisec iu say" ice of
‘reading without the addi¢on of any wates rem the top. #,, = maximum pumping suetion hed she
rruxcroutn depth 10 waick the Sake of a siexeily aperseng Famp ean be jowered bozite delivery flow
eeuses, Aiterratvely 2 pumping suction head may be detined as tke depth at wich @atput falls 20 say
SUE of les cees-c-heal vale Pumping setion head may be obterved from the ouppee flowrate
characterise; priming sacsion iad! cvannox, A fuser measure connected with cUctO€ '3 jj = less of
‘prime tone, the time tat x pump ean oe lett we attr use betore the acbievt2:e suction Cells from Hq 40
Hi, more realistically falls fram Hy, 1014 (H,, +H).

Priccion just - can be divided iato ‘aid and wechanical components. #, ~ frlevion headless is a
Tunctian of Tow rate Q end varies approximately wit Q?

W, = mechanical jriction power lose varies wth pap cadence iteadling rate} and would be expressed
io wars. th measures Hrickion beat generated in Searings, inside ropes, -2 te -Wabing af pistons against
coytinder was and in the ceke-up of slack in mevanisms Rosh Hard it, xffeet cfficianey as discussed.
below.

Efficiency in any device is the rata of the perforrrance actually abtainable 10 that ‘ideally’ obtainable,
When anergy is being pasted along a chain of prucesses - for example from: aman muscle c lied
water - the efffciercy of each prncess can >e expressed as the usefal energy out of it divided by ‘he
exergy put in, There are severa: e%ciencies of pacie.ar interest. The harest to mengine is

nergy given by

weadler

Teg = ergonomic ofiieney

cneryy the sender iceally could have given

Obviously we mus compere "like with Whe", so the wo kaman ontpits show be oxeasuced ewes Hee
sume time and correspond 10 the saime ieve’ of husear effort. A rzachine whieh 's awkiurd (0 Use, Zc.
vite doesn't make etlecave use of the teadler's muscies, wil have a low erguromis efficioney, An
ergonomically idea! machine will nave n= 1. The basi Lastitieauos for emploving a srecdle pump
zatker than 4 cheaper kandoump % previsely because of its higher ergonomic effic.ency, iis use of lee
smuseles rather Gon arm muscles

Mote stealghteoeward foe mecs:tement :s

igs = Indra afctancy = ——2OBR2E gut flow
urputhead and head oss output Row and Cow cass

Mote. = Thee Ed = Muy ¥REY With DUMP heoaghpLt. Ar low heads and hig Hows, My i comedies
tou cov. At hig heads anal low lows, the semoustess of any Ieecage increases and My, ix somedins
(20 low

Ht
H+H,

ha

where H, rises wits QF and weakage flow Gases with #. “The seconé corpeoent 1, is sometimes
called volumetric efficiency and is atfe-tnd both by feakage from tke purmp and. yooce innportant, back,
leakage within the pup doe in Imperfers naaenira valves

stag, = mechanical efceney = TBS HM aches the water

energy put into read’es
a ob cnt and In fon of n

We can visualise Slowing thecagi a pump as underguing # stcies off mensformations even vith an

efficiency “ess than than £0 (: 008}
Potential human + © Pawerepplied © Power applied > —Qumpat
pover The totreadles Thy, 0 water Ths (Puomoing)

power

(lane = in at * Tae

However our interest in "elficicroy’ is caly sevondary. Eificiencies tell how effective the individual
rrinsfermations ace ane haw zeuch roorr shere $s for immpravement Users are only interested in output
flow ender particular vircumsances of aperaor, head and sa an, and how the relative eutgct flows of
rive. pumps compare with their sival enss. [a any humarc-operated device the energy’ cost of operat
is high ‘feu equal energy nuipets, i. raost countries harmaur ‘aboue cogs up th 5D times that of engine
uel, $0 efficiency Is important. Lisfuemately the stuatiens the: favour Gxe of armen energy ae also
those lha: require the capitel 20st of equiproent 6 be very low. Ty some extent high efficiency and low
‘costar iacorcpazible,

In tho flaw chart abovs the sir efficiency shown is ergocumic efficiency. Although chere isa large
lreructe on tis opis and spectalised mexsuremer: zechnigaes (eg. human oxyger consummation), for
UME lesting 1s BON usaA.y pravtwal to separecely Measure ergonomic cchsceney. Tne desige of mmo:
‘weadle purzps allow the operstor © wljust hers position 01 the teadles to get the most ccmrlorabie
combination of stroke, cadence ceyeic rats) and foot faree. The scope for adyustment has ims, 50 tha:
heavy operators in stusrions of very iow “ft or ght operators m9 mtuatioas of bigh if may no be able
1 Find n> opium position

Tr the abgence of dizect sis nf erganoaie efficieney, some indirect fests of treuder ‘comfort’ can be
satle. The pump caz be uperaved ats id-cange heal (ep. 3 or 4 x) with a large sane operator, 2
sretitm aperstor and a small weak one, ‘Tae cadence and stroke they choose Yor sustained panning
should be outed. The medium apereor sheuld not he at either end af the range of possible foot
positions afong the tread, nar shoul she/he he persistently hitting, the treadlc endl stops, With a good
punip these cuudicuns sbould alsy not aise wilh Ure Ieavy or tight operators efiher (Wc this tedium
bead). No operator should fied he hencle position zwkwird or the treadle angles too steep for ankie
confor.

Repeating tne wals idk a minimum head (1.5 ta 3 meters depending on pomp type) and a otaxionm
hese (5 :0 10 eters), the operator choosing new est posigons, wil show whether the ‘medics’
persion can saiccain a Sorta cadence and sunke ay helore. change f either of more than 5%
Indicates F-kely cow ergonomic eficiercy at ove or otter enc wf tae eae reege. lus ualike!y that the
heavies: operaior will be comnfortabie ne e'Ficien a1 the rinimem heud, or #c*ild will he etticient at
the maximum bead.

In the absence of complex equizmect, 1 simple guide to human effort is pulse care. If, og ewe different
occasions a sustained puunpiog tats. she save potsu. las the sezie yilse Zul, czem Hes two effors are
Tikely 9 be Tretetore if ox¢ avcasion v2. choloe of pianp ane -eac) gives & Enger ourpuc
power than the other, orc may essuine che thine: as ike higher averell efficiency (ergonemic and
pump et ciencies convened).
‘The three component parts vf pump eificeney ae the mechanica’, head and flow (er Volume’)
efliciencias. These cat ha app-oxiroaely nieasured 2 isolation as fOuo%s.

forces urd fer Fiction foroes.

provided both inpus fees and friction force ate mseastsee a the st place,

Input fovee F, can be measired al any desined positon along # tale when that treadle is cnved
Slowly, the pump being conaected fo a defined typica: head. Frictioa fowca F; is approicate’y the
farce at the sume point © slon!y move the weadle when the pump head is reduces! te zero (let ar
cout: atthe same Erigh:}. tl,_, Mezsured in his way shoeld exceed 1135 in a new well adjusted perap
ad sill exoeed 9 isa wun pus

IH +H recuzes messureweat of ead, which is Soule, wd fleson head Joss whic 8 ant
FFe-ction hed loss far # givre flow ean te obtained by Est measuriog the reverse heed H, 6. the
heigse the pamup octle pipe is he fave tan its tapas) sevessary to drive hat low throug che pun.

Hy = 4M, where dys ar lest 4 und wypicelly berween 5 and

For a swo-cylinder ueadie pursp, whethes with piston o: diaphrager, aay delivery flow has pussad
through twe values in sens in elthec one cyliader or dhe other, During the reverse-bead rest the cal
flow divides agoat equa:ly between the (a cyl de ary 10 clamp ene pisrens daviag
the reson keep thems in use Cie Mew akerua.es betwee Uylindess
‘The ceverse heac test 38 therefore subjecting cach valve «© only half the peak flew i watld normally
experience - heave the correction factor oF & = 4 (@2%). The ceverse ‘ead also uses stealy flow,
whereas tread: pumps produce a sishrly pulsing flow. This difference raises the faceor k frora 4s
tone 6 As Bis propoctiona: °o G? we sheuld measure M, at euxicnam sermiel flow, waick occurs
full power sad muiniorue: nor head H.,,. Using the esuitune v0 M, yy ARC HE, will give 2 worst
bate vad eifiieney of

Fan

\Whick should not be Tower than 0.5 (30%,

Nee — BIG + 2 = 20,
s0-we need to seasure wihesQ,(dthcule o 9 celeute che deal owrate Q. = Q + Oy Wits apis:
cararyemeal, 0, = pision sake » evincer wea » cadence x 2-2, 4f in coasistent urs. This flew
eftioery should nut be beow 09 (90%)

With a diapsagu 4 ix nevensry -u caibrare che volume displacement fhe eath soroke length, @
talibeation woich may be s.gnifiearly ze error at cae Ulaptragn: diss strongly with variation in warer
preseure. In facs, newswerient af wlinetticifow efficiency Is probably not wortk undertaking with
diaphragm purse.
The measorenmeat uf avera!l puzyp effvieaty Mag ft IMprActICL IDIess calbraced gyreeastic equiproent
i wvadlable to meastce the power output of the operator. IF suck equipment is aveileble and its action is
sicnilar tie. reading) to that of the pump, it way be poss ble <n relate operator pulse cave 2o eperacor
power. Th such cxsee nsing the pimp a exacrly the stee operator power W,, a8 on tre calibrated
feqguipeent will permis she calculation of

_ pew
Spor power

Thane

Bung efficiency wil generally 3e lowest at low heeds {and hence high lows). A worst sase efficiency
cof SO% rsight be just atceptubie, Acernatively T),4g = 0.5 a: fall power cen he used 6 define the
sminioura rated eed ff,

4. Start up, Suction ano Priming

‘Tae nteasnrement of ‘anaided) priming scesion #,, and mex:roum pemping suction bead is faitly
semmighr forward

A dry pomp can 2¢ operated with aa agen delivery port ad a va Lia sacle pipe (oC rawsna! diteneter>
cached to its inlet port. Starting with 10 meiers of saction Gf evallable) exe Suction dept should be
releed -esil he pumcp delivers ster. The suction should be redaoed not :asiee thar, | melee every 2
wiaeies: tis can be done eisher cuntincously or i hal? meser seps. When Ge suction head H, at
wich delivery begins hus brew “oid, it shoal be checked tha: Cie pup will prime within su 1
rmintse from chis depes oven aftor the Sacro: pige x3 completely drained of wate: and left w dry for 20
inte. Once se pump is tuning aed Kec canciag for a: least 5 atinutes at a suction of H, ur less,
the sustien poir: should be gradualy lowered while besdling sloly ai (a depth H,_> the cebvery
Flow stops. This test can he ropested severe: unne, anv she valves of H, averaged, 1 give a mere
rebahle meastre,

Suggested values for H, oad H,, awe 2 ioeters and 6 mers. H's quite variable as ir depends on
ueacug iat zal cas al be Lally affected by ledks zoxmd piss oF through valves, A claphraga
ump should reach a beter prinnieg suctina #, than a pison pump.

Aa aftersatve auprosch i mrasuring priming and scetion cerfonmance is te estimate then From
Jndicee: measurements. Failure wy prime ar filore 2p eosintsin prime occurs when the pumping low
rae Bs Jess thet the leak: ge Flowrate. Tis may be eve te high ‘sukage or low Lowsate ar hath,

“The suction side nf a pueap and she suction pipe are normaly surrounded hy air thac wil Jeak in through
ny fiee cracks. Duricg priming the pistor-eylindsr seal end the valves aze alsa “a wir (aot water as
duting roeral puinging} anv will therefore leak “ester then wier, wetted, The sisnplest farm of priming
rssiscance is 0 sometow' wet these components, far example by poulrng water or. tp ofthe pistin

‘The flow efficiency of 3 pump is lowered by the presense of ay air in the cylinders or diagh
chambers, due to ai being thousands of dimes race carepressible tha

age

Consider « cylincer that contains a ‘deed’ vole ¥ oF ac al atmosphere atessure whea the piston isin
ins iowest position, As ce piston is cased the air valume exphads aad its pressure dros approxioistely
according to Gre retain p. V? — constess, Orly wea the piston has moved « considerable dist
vil he pressuce fneve droppeu enough 16 be below the fnlet pressere and hence open the fulet valve,
‘Thereatte: Farther p:sion movesent will pertorra useful peinging, drawing air (and helew it water) up
the suction pipe. We can cherefore calalite a how efficiency which wssumes perfec: sulk (ro leas)

4
boot expresses the effects of this tesicua) ait. ‘This ideal Cow ef'iciexey depenly upon the suction head
(exuessed as a fraction of tne atmosnzeric neue of 10 mucters) and che rato of volume swept by the
Piston ¥,, So Totus define iw ratios, a nirouiise’ suction S ene a cylinder ratio X.

R

ead volume / swept weiLme = KY,

Table Téea! yolumerric efficiency of cyliacer fas %)

o 01” 02 G3 OF OS 06 Cy O8 “WS
Et a

op 1003000
cn, a rn a]

La

iS

mw 2% D % BS @ % 7 fF Of

mw 3% HO ROH 0 GG

|

, 1 9 6 a RB 0 0 Ul}
sf i 6K]
L102 9 3 6 8 6 o tf 4

Dating priening wt he ratio of dead air volun ts swept volume oan be quite high,
lover 2 for some digphragm paraga ard ovar 1 for piston puaips. These will caerefore ace self-prime for
suctions over 3.5 raters suction and 5.5 meiers sition sespectvely even werk perfect seals, Far gud
521F pring R =tust be kept well below

Diving steady ese however. much of the desd volume a: the bortorn of
cxoupi
atainable,

Ginlecsfchanenens will be
Dy seater. The det sir veleme V,, will he en:ch reduced and R satiog ol below 0.) may be

Using the table above, and eeasurng
again when 3s werking (au: a can
maxioiam values for priming succon #,
Teakege, especially desing scare.

We pump fo asker the valuzs of K when the pun) is dy and
i be tranped above the de.ivery velve}, i is pusstble to predict
nd pumipirg suction 1... Actual values #50 be. less e 09

Regardless of any leakage Losses, ar operciona volumente efictence Cae 10 Caese compression elfects
ssthan sty 0% woule be unzccopiatle. Suck 2 yup would be "springy" and ditioals‘o teadle

Because it uses 9 amar ereigy source 0° vaciable and taknown power. it i noc noemally practical to
test the cHficemoy of a ead yuorp. However a number of fests and measarements are possible to
ckeee that te ergcecenic, ewechanica: ard kydrealic effciencles (defined in the pups} ere eclete ly
high

Witis the sletive peviounce of wu sival pumps, racher onan the absclare peifcemance of a single
‘Bump, that :S zequited, cher satable tess are wvanatble, For example one such test in Zimabubwe it
1991, comparing teadle purrping stk bucket-carrying, established chat he lermer wes three tines as
productive es the lost ina typical Srigation task,

The owe af priming of a seadle gutsp, aad the liits of is ability w draw water from a source same
rncters below itself, cac be ceadily tested aid slw roughly predicted fore measurements of pucip
geomezy. 11 is ahown that a BLNp whose dead ar yoluae exceeds is piston swepl volume ean a
rcrieve high suesion,
‘Troadle pumps nave a lower ead Limi: helew which sere ineftcrency becomes aeceptaaly high. This
Jinstis typically 2 mowers. Altaoaga veacle puraps cam be designe! for higa heads, cfgonomic enc size
venstrainss make them inefficient to ozerate over a bea range O° rtore thas abavt S:l, and eecnomies
icone thle use for heads exceeding 10 meters.

Good performance depends on gereroisly sized vaives sax! uassages (to seduce head bosses), goon! seals
and fast clesing valves (io eure ‘ezercal and extemal leakages, correct gearing (10 allow users t0
choose ergonon.cally efficient vaclenves ard strokes) and smoot, welt lubricated linkages (Ww nsise
‘uochanieal efficiency).