ANSI Vs API Pump Comparison.pdf

8/14/2019 ANSI Vs API Pump Comparison.pdf

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By Ross C. Mackay,Contributing Editor

Which processpump is right

for yourapplication?

In view of these figures, it is apparent that theAPI pumps should be cons idered for higher pres-sure and temperature services chan che lighter duryANS I pump.I n the world of pwnps, there are vo types ofhorizontal end suction centrifugal pumps thatare more conHl'lOnly used chan all the others putcoged1er. 1l1ey are the ANS I pump char ls des ignedand built co the standards of the American NationalStandards Institute, and the AP I pump that nlts The Liquidsche requirementS of che American Petroleum In cons id er in g the arious rypes of iquids han-lnscicuceStandard 610 for General RefineryService . died by these pumps, the fluids in the petrochemi-Q er che years, ANSI designs ha,e become the ca l in dustry are frequentl y classified aspreferred sryle of end suction pumps, not on ly for H) drocarhons. Aggrnsivl Clumicals and Mildchem ica l process applications, bu r also for water Oumicals.and ocher less aggressi \e services. The ANSI H) drocarhom are petroleum-based productS

Standard pro\ides for dimensional interchangeabil- chat are frequently classified as light, iruenn ed lateicy ofpwnps from one nu nufacr urer co another. or At atmospher ic pressure and temperature,The API pwnp is almost the exclusi\e choice lighr h)Urocarbons rend m \aporize, inrenn ed latefor applications in the oil refin- hydrocarbons are liquid, andery industry, where it handles T.aking these fac hea-y hydrocarbons are highlyhigher temperatures and pressure t \iscous or even so lid.applications of a more aggressi\e t t t Aggrmivl Chemicals includenature. While this specification Or S In 0 aCCOUn strong acids , alkalines or oxidiz-also deals with some vertical you can finish up ing agentS that are destructive [shaft models, this arcicle wi ll both equipment and the environ-focus on rhe rnore widely used th fit bl menr. They are also dangerous tohorizontal designs. These single W pro a e plant personnel if allowed ro leak.stage pumps are designed with a and reliable Mild Chrmicals are generallyradially split casing co accommo- easy co handle, and are nor detri-date a back pullout arrangement operating system mental [ eirher equipment orfor ease of maincenance. Tile the environment.major difference between rhe Many of these liquids canrwo styles is reflecced in the casin g pressure design prod uce toxic fluid exposure and vapors if rhey areratings, which are as follows : allowed co leak our of a pump. Vapor release is acommon danger with hydrocarbons due aporize acatmo spher ic conditions or other chem icals char maybe eSJC ar 500 F36 MARCH 2004 z o n e c o m PUMPS SYSTEMS


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If a ''apor release is e.


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.-

L _ ....J Figure 3. Typical AN SI mpThe drawback of chis design is for most of

these pumps tha t che PSH required ls often considerably greater chan ir would be in the end suctionarrangement. More PSH is needed in order coaccommodate the friction losses in che corwous

path from the suction flange co theof che im.peller

Back Coverrr ngementsOrle of che major differencesberween the ANSI and API pump cas-ings is in the m:mner in which ilie back

CO\'er is secured co the casing.In che r u ~ S design shown inFigure 3 the back ctwer and gasketare held against the purnp casing bythe bearing frame adapcor which ismost frequendy supplied in cast iron.This usually results in a gap berweenthe mating faces of the frame adapcorand che pump casing that has thepotencial co permit une\en rorquingofche boles. In che e\enc of a higherchan-normal pressuriz.acion of che casing by cheprocess syscern . chls tnay cause a fracmre of cheadapcorllle AP I design in Figure 4 boles che back CO\ erdirecdy co che casing and uses a confined controlled

PolarisPumps are AmericanMade fromall cast parts of 28 chrome Iron -so they'll work HARDER.last LONGER and s a ~ youtime and moneyOur unique modular designallows field upgrades andconversions. And Polarispartsarereadily availableso down time s limited.For sales& r v l c eofPolarisPumps call:800624 7069www.polarlspumps.com

38 MARCH 2004 V . V . z o n e c o m PUMPS SYSTEMS


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a r c h 0 4 P ~ P S S . S Y S p 2 6 l 2 l7/04 LO: 45 A." Page 39

compre-ssion gaske-t withmetal to metal firs. T h eacbp tor is bo lted in depend< -n d y to the back cm'C':r anddoes not p lay a pan in thepr


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ele\'ated te mperatures. As che pump comes up mcemperarure in such cases, any e:


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pump rather than a combination of che impeller, Contributing EdiUJr Ross Mackn)' has ovrr 40casing and back cover. In add ition, b()[h the indi- )'fars i11 thr pump industr)-man)' o thrm working,idua l parrs and complete pumps are a-ailable fairly with both ANSI andAPIpmnp applicatiom. Todn)'quickly. This can make ic more cost effeccive co hr sprcialius in hrlping companif1 i11c1 t asr theirrep lace raeher chan repair che pares, unless che wee pump rt'liahilitj and rt'ducr oprrating and maintr-ends are made of che more e.xocic alloys. lc ls dear, ttllncr costs through comulti11g and rducation. Hr canin the case of non-mecallic pumps (wh ich may also hr rrachrdat 1-800..465-6260 or tlll'oughhiswrh siuconform to ANSI standards), chat the componentS at www.rossmacka)'.commuse be replaced, as chey general- 1y cannot be repaired .AP I pumps, howe\er, are gen erally more economical co repairchan co rep lace. These w1 ics areusually installed in more ruggedducies and haz.ardous app licat ionsin refineries or ocher petrochemica l indusrries, and are consequent y more durable and moreexpensive. Deli\'ery periods arealso frequendy longer, and tilepares more costly chan their ffi'ISIequi\tlenr.s--particular thr casrsand impel/us.This makes it \'ery cempcingco source these pares from anafcer-rnarker supplier rather dunthe Original Equipment Manufacturer (OEM) . It should benoted, chough, chat the majorpares of a ce ntrifugal pump (i.e.che casing, che impeller and theback CO\er) are all case from parterns irwolving incricace hydra ulicdesigns , wh ich are of a propriecarynamre. These pares are also theones chat pro\ide rhe hydra ulicperformance of the purnp. W'hileche pares mighc be a\ailable frornafcer-rnarkec suppliers at slighdylower prices than they are frornche OEM, char cost Sa\ing wlllfade inco in sign ifica nce if chepum.p does noc meet ics hydraulicperformance. Your OEM canaccept che responsibiliry for thesu bseq uent hydrau lie performance of these rep lace men r pares .

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By taklng these factors incoaccount, you can fin ish up wlchreliable pumps due have beerlpropery selected to provide a profitable arld reliable operatingsystem .P S L ~PUMPS& SYSTEMS ww.v pump-zo ne. om MARCH 2004 41

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ANSI Vs API Pump Comparison.pdf