Centrifugalpumpscanbedesignedwithanumberofimpellersinseries串联,连续toattainahighfinaldeliverypressure.Theyarepopularbecausetheyareverysimpleinconstruction结构,andcanproducesmooth平稳,constant连续,non-pulsating无脉动的discharge排出.Avertical立式的,single-stage单级,single-suction单吸centrifugalpumpforgeneralmarineduties普通船用isshownbelow.Thepumpingelementismadeupofatopcover顶盖,apumpshaft泵轴,animpeller叶轮,abearingbush轴承套andasealing密封arrangement装置aroundtheshaft.Thesealingarrangementmaybeapackedgland填料压盖oramechanicalseal机械密封andthebearinglubricationsystemwillvary变化accordingtothetypeofseal.Replaceable可更换的wearrings抗磨环arefittedtotheimpellerandthecasing.Incentrifugalpumps,besidesverticalpumps,therearehorizontalones;besidessingle-stagepumps,therearemulti-stageones;besidessingle-suctionpumps,therearedouble-suctionones.verticalpump立式泵horizontalpump卧式泵single-stagepump单级泵multi-stagepump多级泵single-suctionpump单吸泵double-suctionpump双吸泵Besidesvolute蜗壳type,anothertypeofcentrifugalpumpisdiffuser导轮type.Aringisfixedtothecasingaroundtheimpeller叶轮,inwhichtherearepassages通道formedbyvanes叶片.Thepassageswidenoutinthedirectionofliquidflowandacttoconvert转换thekineticenergy动能oftheliquidintopressureenergy压力能.Whenstartingacentrifugalpumpthesuctionvalve吸口阀isopenedandthedischargevalve排出阀leftshut;themotorisstartedandtheprimingunit引水装置willprimethesuctionline.Oncethepumpisprimedthedeliveryvalvecanbeslowlyopenedandthequantityofliquidcanberegulatedbyopeningorclosingthedeliveryvalve.Whenstoppingthepumpthedeliveryvalveisclosedandthemotorstopped.Reciprocatingpumpsandrotarypumpsarepositivedisplacement正容积typebecausetheydischargeanearlyconstantamount定量的ofliquidregardlessof不管pressure.Ifthedischargevalveisclosed,theybuildupaburstingpr