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Memorandum

To: Professor Alan S. FeitelbergFrom: Muhammad Khan and Saddmun Ahsan (subgroup of Th4)Date: September 18 !"14

Re: #e$ apparatus for measuring pump performan%e

Per the instru%tions %ontained in &our memo dated !' August !"14 $e ha e tested the ne$apparatus manufa%tured b& *lin +ngineering b& flo$ing $ater through a %losed loop po$ered b&a Mar%h Pumps TM T+ ,- M magneti% dri e pump. The $ater flo$ rate $as aried bet$een !and !" gallons per minute (gpm) and the reading at ea%h of the t$o pressure gauges $asre%orded. The %urrent dra$n from the pump motor displa&ed b& the ammeter $as also re%orded.

The s&stem %ur e $hi%h tra%/s head loss throughout the entire piping %ir%uit $as determined before the e0periment $as %ondu%ted. t ta/es into a%%ount fri%tion from motion through the piping and resistan%e en%ountered at fittings su%h as elbo$s tees and globe al es. The ar%&

2eisba%h e3uation $as used to %onstru%t relationships bet$een fluid me%hani%al 3uantities su%has the -e&nolds number and the Fanning fri%tion fa%tor ( f ) rele ant to the pump test. The totalhead loss %an be %al%ulated b&1+3uation 1 $hi%h ta/es into a%%ount head loss from bothfri%tional effe%ts at fittings and rotameter.

hloss = v

2

2 g (4 f L D + K f )+ P g (1)v represents the a erage elo%it& of the fluid g the a%%eleration due to gra it& P the pressuredifferen%e a%ross the rotameter and is a /ineti% energ& %orre%tion fa%tor (1." for full&de eloped turbulent flo$).

The data obtained $hile %ondu%ting the e0periment are summari5ed in Table 1. The t$o pressuregauges differed in height b& appro0imatel& ,." in%hes $hi%h a%%ounts for the head gain due tothe %hange in gra itational potential energ& of the pro%ess fluid.

These data are used to %onstru%t the pump %ur e (for a !. in%h impeller) sho$n in Figure 1$hi%h delineates the relationship bet$een the head gain of the fluid the sum of the gains due tothe pressure gradient a%ross the pump and the %hange in gra itational potential energ& ersusthe flo$ rate. The pump %ur es for the 6." in%h and 6. in%h impellers $ere determined based onthe fa%t that fluid elo%it& is linearl& dependent on the diameter 1 $hi%h implies that the first termin +3uation 1 (%orresponding to head loss due to fri%tional effe%ts at fittings and 7oints) aries$ith the s3uare of the diameter (sin%e it depends on the s3uare of the elo%it&) as is indi%ated b&+3uation ! belo$. 2ith the alue of the fri%tional head loss alread& %al%ulated for a !. in%himpeller +3uation ! $as emplo&ed to %onstru%t the other t$o pump %ur es.

[ v2

2 g (4 f L D + K f )]new = [ v2

2 g (4 f L D + K f )]o ld( D new Dold )2

(!)

8/9/2019 Revised Lab 1 Pump Curve

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The error in the e0periment %ould ha e been redu%ed b& ta/ing more than one set of readings andha e one person re%ord the measurements ersus different members of the group. Furthermore amore a%%urate %ur e $ould ha e been produ%ible if $e in%remented b& a smaller flo$ rate and%olle%ted more data points.

Figure 1: Pump Curve illustrating relationship between head gain and flow rate

The effi%ien%& $as %al%ulated b& %omputing the ratio bet$een the fluid $or/ and the totalamount of energ& deli ered b& ele%tri%al pump motor ea%h of $hi%h is easil& %al%ulated b&%onsulting +3ns. 9 and '9 from the %ourse notes 1. Table 1 summari5es the effi%ien%ies and theele%tri%al energ& in the e0periment.

RotameterReading

(gpm)

Gauge 1Reading

(psig)

Gauge 2Reading

(psig)

AmmeterReading

(A)

FluidWork

(horsepower )

le!tri!alnerg"

A#aila$le(horsepower )

%%i!ien!"

! " 11.' !.4 "."16 4 ".6'"1 6.,':4 " 11.' !. 1 "."!,", ".6'8;, ,.64:' " 11.1 !. "."688' ".6,48 1".6,:8 " 1"., !.'" "."4;;4 ".68!! 16.",:

1" " 1".1 !.' "." 8;6 ".68; 1 .16:1! " ;.6 !.," "."' 4' ".6;'; 1'.4;:

1!.8 " 8.;" !.,1 "."''4' ".6;86, 1'.'8:

Table 1: Summarizes measurements taken during the e periment and !al!ulated energies and effi!ien!ies of the!losed"loop pro!ess#

-eferen%es1. Professor Feitelberg personal %ommuni%ation !; August !"14.