阀门词汇-英文版-Valve-Glossary.doc

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1、ActuatorDeviceusedtoopen/closeorcontrolthevalve.Keytypesincludeelectrical,hydraulicandpneumatic.Movementmaybequarter-turnormulti-turn.Actuatorsmaybeusedwhen(i)valvesareremotelylocated(eg,onpipelines)(ii)valvesarelocatedinhazardousareas(iii)manualoperationwouldbe

2、time-consuming(eg,withlargervalves)AirvalveValvethatisusedtocontroltheflowofair.Flowsarenormallysmall,sosolenoidvalvesaresuited.BackpressureThepressureexertedonthedownstreamsideofavalveseat.BallvalveAquarter-turnvalvewithasphericalclosingelementheldbetweentwosea

3、ts.Characteristicsincludequickopeningandgoodshut-off.Ballvalvesarewidelyusedason/offvalvesinthechemicalprocessandotherindustries.Specialdesigns(withVnotchesorfingers)areavailableforthrottlingapplications.Largervalveswithheavierballs(eg,onpipelines)mayusetrunnion

4、stohelpsupporttheballandpreventdamagetosoftinternals.Designsaretypically,one,twoorthreepiece.BellowsSealingdevicewhichpreventslinemedialeakingbetweenthestemandthebody.ButterflyvalveAquarter-turnvalvewhichhasacirculardiskasitsclosingelement.Thestandarddesignhasth

5、evalvestemrunningthroughthedisk,givingasymmetricalappearance.Laterdesignsoff-setthestem,sothatthedisk‘cams’intothevalveseat.Advantagesincludelesswearandtearonthediskandseats,andtightershut-offcapabilities.ManydesigntypesareavailableincludinginexpensiveTeflonorre

6、silientseatsforuseinwater(treatment)plants,etc.Moreexpensivemetalseatscanbeusedwherehightemperaturesoraggressivechemicalsareencountered.So-called“HighPerformance”butterflyvalvesofferzeroleakagedesignsandhavebeenappliedinboththechemicalsandhydrocarbonprocessingse

7、ctors.BypassvalveAsmallborevalvefittedinparalleltoalargermainvalve.Bypassvalvesareusedtoreducethedifferentialpressureacrossthemainvalvebeforethislattervalveisopened(asotherwisethislarger,moreexpensivevalve,maysufferdamagetointernalcomponents).CheckvalveAvalvetha

8、tisdesignedtoallowthefluidtoflowinagivendirectionbutclosestopreventbackflow.Typesincludeswingcheck,tiltingdisccheckandwafercheck.Checkvalves(alsocallednon-returnvalve