阀门流量计算方法介绍

1、阀门流量计算方法如何使用流量系数HowtouseCv阀门流量系数(Cv)是表示阀门通过流体能力的数值。Cv越大，在给定压降下阀门能够通过的流体就越多。Cv值1表示当通过压降为1PSI时，阀门每分钟流过1加仑15c的水。Cv值350表示当通过压降为1PSI时，阀门每分钟流过350加仑15oC的水。Valvecoefficient(Cv)isanumberwhichrepresentsavalvesabilitytopassflow.ThebiggertheCv,themoreflowavalvecanpasswithagivenpressuredrop.ACvof1meansavalvewill

2、pass1gallonperominute(gpm)of60Fwaterwithapressuredrop(dp)of1PSIacrossthevalve.ACvof350meansaovalvewillpass350gpmof60Fwaterwithadpof1PSI.公式1FORMULA1流速：磅/小时(蒸汽或水)FLOWRATELBS/HR(SteamorWater)在此:Where:dp=压降，单位：PSIdp=pressuredropinPSIF=流速，单位：磅/小时F=flowrateinlbs./hr.I=比容积的平方根，单位：立方英尺/磅(阀门下游)3=squarerootof

3、aspecificvolumeinft/lb.(downstreamofvalve)公式2FORMULA2流速：加伦/分钟（水或其它液体）在此：Where:dp=压降，单位：PSIdp=pressuredropinPSISg=比重Sg=specificgravityQ=流速，单位：加伦/分钟Q=flowrateinGPM局限性LIMITATIONS上列公式在下列条件下无效:Aboveformulasarenotvalidunderthefollowingconditions:对于可压缩性流体，如果压降超过进口压力的一半。Forcompressiblefluids,wherepressuredr

4、opexceedshalftheinletpressure.对于不可压缩性流体，如果压降产生空穴或闪蒸。Fornon-compressiblefluids,wherepressuredropcausescavitationorflashing.对于双相流体，如蒸汽-水混合流体。Fordual-phaseflowsuchassteam-watermixtures.例子EXAMPLE通过DN350,压力等级Class900的压力密封闸阀，水温400F，压力为1500PSIG5,000,000磅/小时的压降是多少？Whatisthepressuredropthrougha14Class900pres

5、suresealgatevalvewith4001500PSIG,and5,000,000lbs/hrflowrate?解：采用公式1Solution:Useformula1.F=5,000,000朋=0.137（从水温为400oF的表中得到）o=0.137（fromchartforwaterat400F）Cv=9150（来自本页）Cv=9150（frompage26）亠/F疗5t000t000XJ37Jdp=（葩H）=163.5X9159）流速为oFwater,1相同，求=（1J8）DN350 xDN300 xDN350，压力等级Class900缩喉管压力密封闸阀，其它条件与例压降。What

6、isthepressuredropthrougha14x12x14Class900Venturipressuresealgatevalvewiththesameconditionsasexample1.解：采用公式1Solution:Useformula1.Cv=6285（来自本页）-1.4PSICv=6285(frompage26)dp=/5,000,000X.137=（172=PSII63,5x6285丿温度900F,压力1200PSI，流速500,000磅/小时的蒸汽应用中压降小于5PSI的压力等级Class2500闸阀的最小通径是多少？WhatisthesmallestClass250

7、0gatevalvethatwillhavelessthana5PSIpressuredropin900F,1200PSIsteamserviceataflowrateof500,000lbs/hr?解：采用公式1Solution:Useformula1.F=500,000=0.785(来自900oF,1200PSIG蒸汽表)o0.785(fromchartforsteamat900F,1200PSIG)500.000玄.785=2759=2.24最接近的、较大的Cv是DN250压力等级Class2500闸阀，其Cv是3130。这里是压降小于5PSIG的最小的阀门。Theclosesthigh

8、erCvisa10Class2500gatewithaCvof3130.Thisisthesmallestvalvewithapressuredroplessthan5PSIG.水和蒸汽的备选特性SelectedPropertiesofWaterandSteam水的丫歹（下游）肩ForWater(Downstream)所有压力等级温度(oF)oTemperature(F)All100200300400500600Pressures0.1270.1290.1320.1370.1430.154蒸汽的封(下游)MForSteam(Downstream)压力PSIG温度(of)oTemperature

9、(F)阀座端口流速计算PressurePSIGSat500600700800900100011001001.972.202.322.442.542.642.742.842001.461.611.681.771.851.952.002.073001.211.301.381.461.521.601.651.714001.061.111.191.261.321.381.431.475000.9500.9791.061.121.181.231.281.336000.8650.8950.9601.021.081.131.171.227000.8010.8800.9410.9941.041.081.128

10、000.7470.8150.8750.9260.9721.011.059000.7010.7590.8210.8700.9140.9550.9910000.6620.7100.7730.8160.8650.9170.9411000.6280.6700.7320.7810.8230.8720.9012000.5980.6290.6950.7450.7850.8130.8613000.5700.5900.6620.7100.7520.7890.8314000.5450.5590.6330.6830.7230.7520.7916000.580.630.670.700.7418000.540.590.

11、630.660.6920000.500.550.590.620.6525000.410.480.520.550.5830000.310.420.460.490.5240000.170.320.380.420.4450000.160.240.320.360.3960000.160.190.280.320.35CalculatingSeatPortVelocity下列公式可以用来计算任何阀门的阀座流速：Thefollowingformulascanbeusedtocalculateseatportvelocityinanyvalve:流量（磅/小时）:流速：（英尺/秒）=F()225AFlow(l

12、bs/hr):vel:(fps)=Flow(lbs/hr):vel:(fps)=2F()25A0.32Q流量（加仑/分钟）:流速:（英尺/秒）=AFlow(GPM):vel:(fps)=0.32QA在此：Where:F=流量（磅/小时）F=flow（lbs/hr）=比容积的平方根2A=阀座端口面积（英寸A=seatportarea（in）Q=流量（加仑/分钟）Q=flow(gpm)例:DN300型号58809(压力等级Class900)止回阀，流体介质为温度500F，压力200PSIG的蒸汽,流速为90,000磅/小时，求阀座端口的流速？Example:Whatistheseatportvel

13、ocityina12Figure58809(Class900)checkvalvewithaflowrateofo90,000lbs/hrofsteamat500Fand200PSIG?）解:解:从蒸汽表得为1.61，从阀座端口面积表A得阀座端口面积为78.5英寸2Answer:Fromthesteamtables7is1.61,andfromtheseatportareatableAis78.5inF()2F()2流速：（英尺/秒）=25A90,000(1.61)225(78.5)英尺/秒Vel(fps)=F()225A90,000(1.61)225(78.5)例：DN300型号180（压力

14、等级150）旋启式止回阀，流体介质为温度500F，压力200PSIG的蒸汽，流速为90,000磅/小时，求阀座端口流速？Example:Whatistheseatportvelocityina12Figure180(Class150)SwingCheckValvewithaflowrateof90,000lbs/hrofsteamat500乍and200PSIG?解:查表得为1.61，A为113.1英寸3Answer:FromthetablesVel(fps)=流速:（英尺/秒）=F()225AF()290,000(1.61)=82.525(113.1)290,000(1.61)英尺/秒=82

15、.5fpsvT25A25A25(113.1)局限性LIMITATIONS流速公式在下列条件下无效:Velocityformulasarenotvalidunderthefollowingconditions:对于可压缩性流体，如果压降超过进口压力的一半。Forcompressiblefluids,wherepressuredropexceedshalftheinletpressure.对于不可压缩性流体，如果压降产生空穴或闪蒸。Fornon-compressiblefluids,wherepressuredropcausescavitationorflashing.对于双相流体，如蒸汽-水混合

16、流体。Fordual-phaseflowsuchassteam-watermixtures.注意NOTE在确定止回阀通径时，最适宜的工作流速应该位于这些范围内:Whendeterminingsizingforcheckvalves,theoptimumoperatingvelocitiesshouldfallwithintheseranges:BB旋启式止回阀：55至115或135至240BB截止止回阀:BB截止止回阀:40至120PS提升式阀瓣止回阀：55至200PSY形止回阀：148至200BBSwingCheckValves-55to115or135to240BBStopCheckVal

17、ves-40BBStopCheckValves-40to120PSTiltDiscCheckValves-55PSTiltDiscCheckValves-55to200PSStopCheckValves-40to180PSY-StopCheckValves-148to200阀座端口面积“A英寸2)适用于螺栓阀帽阀门SEATPORTAREAAFORBOLTEDBONNETVALVES(in2)阀门通径ValveSize压力等级PressureClass150300600900150011/2221/234681012141618202430361.83.14.97.112.628.350.378

18、.5113.1137.9182.7233.7291.0424.5671.9969.01.83.14.97.112.628.350.378.5113.1137.9182.7227.0283.5424.5672.0942.01.83.17.112.628.348.774.7108.4130.2170.9213.8261.6380.1590.9851.21.83.14.96.511.826.044.271.0100.0117.91.52.84.06.010.322.738.560.084.5101.6阀座端口面积(英寸2)适用于压力密封闸阀，截止阀，提升式阀瓣止回阀SEATPORTAREAFORPR

19、ESSURESEALGATE,2GLOBE,TILTDISCCHECKVALVES(in)阀门通径ValveSize压力等级PressureClass6009001500250021/23468101214161820245.45.49.623.239.961.088.7173.8310.255.95.910.321.737.758.480.597.2125.2156.7198.0287.33.34.98.318.931.948.769.082.5108.4137.9170.9247.52.43.65.912.621.734.547.258.276.697.2117.9170.9阀座端口面积(

20、英寸2)适用于压力密封Y形截止阀SEATPORTAREAFORPRESSURESEALY-GLOBEVALVES(in2)阀门通径ValveSize压力等级PressureClass9001500250081012141618202439.961.986.686.6135.4135.4198.1302.639.961.986.686.6135.4135.4198.1302.627.242.860.186.686.6135.4135.4198.1BoltedBonnet开胆度%与流駅系数町%Openvs%Cu开胆度%与流駅系数町%Openvs%Cu$do舊曾切WAHAn阀门开片度rl分比02C0

21、0SD1Q0PercentofFullOp&nCv全开狀态下流鼠系薮百分比图1螺栓阀帽截止阀Figure1BoltedBonnetGlobeValves(1)当开启度小于10%时，不建议用于节流应用。notrecommendedforthrottlingatlessthan10%Open.GateValvesFULLOPENCv阀门通径ValveSize压力等级PressureClass150300600900150011/2212/234568101214161820243036165307490710130020903110572089351335016275215602872035760

22、52165862351295001653074907101300311057208935133501627521560278903484051050847651258251653074907101300311055408495128001537029170262703214046710755301142506501220285050257850114751391013827040060010701600250043756840998012000PressureSealGateValvesFULLOPENCv阀门通径ValveSize压力等级PressureClass60090015002500

23、21/23468101214161820243505259252150377557508600102751342517200209503085035045085019253575525075502754157301675292545506570190275460110019703130453555007210压力密封缩喉管闸阀全开状态下的流量系数CvPressureSealVenturiGateValvesFULLOPENCv阀门通径ValveSize压力等级PressureClass600900150025008x6x815701385118581510 x8x102795238521551

24、43012x10 x12448540653450251514x12x14731062855640385516x14x16900072006270441518x16x181100097608465616520 x18x20142001218511120796022x20 x22168001600514130964526x24x262500023000螺栓阀盖旋启式止回阀全开状态下的流量系数CvBoltedCapSwingCheckValvesFULLOPENCv阀门通径ValveSize压力等级PressureClass150300600900150011/2221/23468101214161

25、820243063142217356716141429615720631682753927401992234057209713922724649913343359544070459840129121954035860516232508406963161113155641520螺栓阀帽截止阀全开状态下的流量系数CvBoltedBonnetGlobeValvesFULLOPENCv阀门通径压力等级PressureClassValveSize150300600900塞形塞形塞形塞形或V形或V形或V形或球形端口球形端口球形端口球形阀瓣阀瓣阀瓣阀瓣阀瓣阀瓣阀瓣PlugorV-PortPlugorV-Po

26、rtPlugorV-PortPlugorBallDiscBallDiscBallDiscBallDiscDiscDiscDisc11/223232123243404340434021/270707031009210092100929041851701851701851701705297273644040544040544040588107458107457801012601150126012189018901810压力密封提升式阀瓣止回阀全开状态下的流量系数CvPressureSealTiltingDiscCheckValvesFULLOPENCv阀门通径ValveSize压力等级Pressu

27、reClass9001500250021/2958060314613294426823014666275363558106294062710172214651020122420211014201429552550177516394533952355184900436530252062755465370524929580605465压力密封缩喉管提升式阀瓣止回阀全开状态下的流量系数CvPressureSealVenturiTiltingDiscCheckValvesFULLOPENCv阀门通径ValveSize压力等级PressureClass1503006008x6x810 x8x1012x1

28、0 x1214x12x1416x14x1618x16x1820 x18x2022x20 x2256595515502175266035504410565048084513201900229530553930492032056592012751598212027253335球形止回阀，截止止回阀，提升式止回阀的流量特性曲线CharacteristicFlowCurvesforGlobeStop,Stop-Check,Lift-CheckValves小于全开状态的估计流量系数CvEstimatingCvForLessThanFullyOpenValves2002004MJ63MPercentofF

29、ullOpenCv少开肩狀杰F侑淋I岳救百分比.1JDo64uio-u&LedO-A-CA糾口开fl度.頁畫图2球形止回阀，截止止回阀和提升式止回阀Figure2GlobeStop,Stop-CheckandLift-CheckValves压力密封T形球形止回阀，截止止回阀和提升式止回阀阀全开状态下的流量系数CvPressureSealT-GlobeStop,Stop-CheckandLift-CheckValvesFULLOPENCv阀门通径ValveSize压力等级PressureClass9001500250021/234681012901051954558001250182065951

30、703956951085158045651052654707501100142205压力密封Y球形止回阀，截止止回阀和提升式止回阀阀全开状态下的流量系数CvPressureSealY-GlobeStop,Stop-CheckandLift-CheckValvesFULLOPENCv阀门通径ValveSize压力等级PressureClass600900150025008101214161820242025302546004300765073251180016450175027253825365060005825912513500175027253825365060005825912513500

31、11751875265040753775662562259050算。不建议将闸阀用在节流应用中表中所列流量系数仅适用于全开状态下的阀门。不是全开状态的流量系数可以采用适用于提升式阀瓣止回阀和截止阀的流量特性曲线进行估Theflowcoefficient(Cv)listedinthetablesapplytofullyopenvalvesonly.Flowcoefficientsatotherthanfullyopenmaybeapproximatedbyuseofthecharacteristicflowcurvesfortiltingdisccheckandglobevalves.Gatevalvesarenotrecommendedforthrottlingservice.例:DN300，压力等级Class900的美国太平洋压力密封截止阀在开气度为1/4时的流量系数是多少?EXAMPLE:WhatistheCvofa12inchClass900P