阀门流量计算方法.docx

1、阀门流量计算方法阀门流量计算方法如何使用流量系数How to use Cv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1 PSI时，阀门每分钟流过 1加仑15oC的水。Cv值350表示当通过压降为1 PSI时，阀门每分钟流过 350加仑15oC的水。Valve coefficient (Cv) is a number which represents a valves ability to pass flow. The biggerthe Cv, the more flow a valve can pass wit

2、h a given pressure drop. A Cv of 1 means a valve willpass 1 gallon per minute (gpm) of 60 F water with a pressure drop (dp) of 1 PSI across the valve.A Cv of 350 means a valve will pass 350 gpm of 60 F water with a dp of 1 PSI.公式1FORMULA 1流速：磅/小时（蒸汽或水）FLOW RATE LBS/HR (Steam or Water)63.5 vdp在此：Wher

3、e:dp =压降，单位：PSIdp = pressure drop in PSIF =流速，单位：磅/小时F = flow rate in lbs./hr.| =比容积的平方根，单位：立方英尺 /磅(阀门下游)= square root of a specific volume in ft /lb.(downstream of valve)公式2FORMULA 2流速：加伦/分钟（水或其它液体）FLOW RATE GPM (Water or other liquids)在此：Where:dp =压降，单位：PSIdp = pressure drop in PSISg =比重Sg = speci

4、fic gravityQ =流速，单位：加伦/分钟Q = flow rate in GPM局限性LIMITATIONS上列公式在下列条件下无效:Above formulas are not valid under the following conditions:a.对于可压缩性流体，如果压降超过进口压力的一半。b.For compressible fluids, where pressure drop exceeds half the inlet pressure.c.对于不可压缩性流体，如果压降产生空穴或闪蒸。d.For non-compressible fluids, where pre

5、ssure drop causes cavitation or flashing.e.对于双相流体，如蒸汽-水混合流体。f.For dual-phase flow such as steam-water mixtures.例子EXAMPLE1.通过DN350,压力等级Class 900的压力密封闸阀，水温400F,压力为1500 PSIG,流速为5,000,000 磅/小时的压降是多少？2.What is the pressure drop through a 14 Class 900 pressure seal gate valve with 400 Fwater, 1500 PSIG, a

6、nd 5,000,000 Ibs/hr flow rate ？3.解：采用公式14.Solution: Use formula 1.F = 5,000,000=(从水温为400F的表中得到)曲 = (from chart for water at 400 F)Cv = 9150 (来自本页)Cv = 9150 (from page 26).=/ F、盯 ? = p.000.000 x J37? t 63.5 Cv、 I63,5 X 91 59 丿 二 CM込 1,4 PSI2.DN350 x DN300 x DN350,压力等级 Class 900缩喉管压力密封闸阀，其它条件与例 1相同，求压

7、降。3.What is the pressure drop through a 14x12x14 Class 900 Venturi pressure seal gate valve with the same conditions as example 1.4.解：采用公式15.Solution: Use formula 1.6.Cv = 6285 (来自本页)7.Cv = 6285 (from page 26)dp = QCCUQJx .1即 f = (1.72 = 2 9 PSI8.V 63.5 X 6235 丿9.温度900oF,压力1200 PSI，流速500,000磅/小时的蒸汽应

8、用中压降小于 5 PSI的压力等级Class2500闸阀的最小通径是多少？10.What is the smallest Class 2500 gate valve that will have less than a 5 PSI pressure dropin 900 oF, 1200 PSI steam service at a flow rate of 500,000 lbs/hr ？11.解：采用公式112.Solution: Use formula 1.F500,000 (来自 900F, 1200 PSIG 蒸汽表)(from chart for steam at 900 F, 1

9、200 PSIG)63.5 63,5 x 2.24最接近的、较大的 Cv是DN250压力等级Class 2500闸阀，其Cv是3130。这里是压降小于 5 PSIG的最小的阀门The closest higher Cv is a 10 Class 2500 gate with a Cv of 3130. This is the smallest valve with a pressure drop less than 5 PSIG.水和蒸汽的备选特性Selected Properties of Water and Steam水的(下游) V For Water (Downstream)所有压力

10、等级AllPressures温度(F)Temperature ( oF)100200300400500600L V蒸汽的(下游)For Steam (Downstream)压力PSIGPressurePSIG温度(F)Temperature ( oF)Sat50060070080090010001100100200300400500600阀座端口流速计算Calculating Seat Port Velocity下列公式可以用来计算任何阀门的阀座流速：The following formulas can be used to calculate seat portvelocity in any

11、 valve:25A25AFlow (lbs/hr): vel: (fps)=流量（加仑/分钟）:流速:（英尺/秒）=Flow (GPM): vel: (fps)=AA在此：Where:F =流量（磅/小时）F = flow (Ibs/hr)r| =比容积的平方根square root of specific volumeA =阀座端口面积（英寸2）2A = seat port area (in )Q =流量（加仑/分钟）Q = flow (gpm)例:DN300型号58809 (压力等级Class 900)止回阀，流体介质为温度 500 F,压力200 PSIG的蒸汽，流速为90,000磅/

12、小时，求阀座端口的流速Example:What is the seat port velocity in a 12 Figure 58809 (Class 900) check valve with a flow rateof 90,000 lbs/hr of steam at 500 F and 200 PSIG解:Answer:From the steam tables 兴 is , and from the seat port area table A is 78.5 in例:DN300型号180 （压力等级150）旋启式止回阀，流体介质为温度 500F,压力200 PSIG的蒸汽，流速

13、为90,000磅/小时，求阀座端口流速？Example:What is the seat port velocity in a 12 Figure 180 (Class 150) Swing Check Valve with a flow rate of 90,000 lbs/hr of steam at 500 F and 200 PSIG解:Answer:From the tables is and A is 113.1 in局限性LIMITATIONS流速公式在下列条件下无效:Velocity formulas are not valid under the following cond

14、itions:For compressible fluids, where pressure drop exceeds half the inlet pressure.For non-compressible fluids, where pressure drop causes cavitation or flashing.For dual-phase flow such as steam-water mixtures.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：Whendetermining sizing for check valves, the optimum o

15、perating velocities should fall within these ranges:BB旋启式止回阀：55 |占 至 115；莎或135 至240BB截止止回阀：40 |亡至120 |PS提升式阀瓣止回阀：55疳至200桂：|PSY形止回阀：148 |.：. 至 200 |BB Swing Check Valves - 55 /： to 115 |必：| or 135 |注:-| to 240 |:九 |BB Stop Check Valves - 40 |-A |to 120 巴：|PS Tilt Disc Check Valves - 55 血 to 200 晁PS S

16、top Check Valves - 40 |to 180 订PS Y- Stop Check Valves - 148 to 200阀座端口面积“ A （英寸2）适用于螺栓阀帽阀门SEAT PORT AREA A FOR BOLTEDBONNET VALVES (irn)阀门通径Valve Size压力等级Pressure Class150300600900150011/222厶3468101214161820243036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SEAT PORT AREA FOR PRESSURE SEAL GATE,GLOBE, TILT DIS

17、C CHECK VALVES (in 2)阀门通径Valve Size压力等级Pressure Class6009001500250021/2346810121416182024阀座端口面积（英寸2）适用于压力密封Y形截止阀SEAT PORT AREA FOR PRESSURE SEAL Y-GLOBEVALVES (in 2)阀门通径Valve Size压力等级Pressure Class90015002500810121416182024螺栓阀帽闸阀全开状态下的流量系数 CvBolted BonnetGate Valves FULL OPEN Cv阀门通径Valve Size压力等级Pre

18、ssure Class150300600900150011/2221/2345681012141618202430361653074907101300209031105720893513350162752156028720357605216586235129500165307490710130031105720893513350162752156027890348405105084765125825165307490710130031105540849512800153702917026270321404671075530 11425065012202850502578501147513910

19、138270400600107016002500437568409980 12000than 10% Open.压力密封闸阀全开状态下的流量系数 CvPressure SealGate Valves FULL OPEN Cv阀门通径Valve Size压力等级Pressure Class6009001500250021/ 23468101214161820243505259252150377557508600102751342517200209503085035045085019253575525075509150119501557519200 276752754157301675292545

20、5065707890 10325 13425 16825 241501902754601100197031304535550072109215 11450 16575压力密封缩喉管闸阀全开状态下的流量系数 CvPressure SealVenturi Gate Valves FULL OPEN Cv阀门通径Valve Size压力等级Pressure Class600900150025008 x 6 x 815701385118581510 x 8 x 10279523852155143012 x 10 x 12448540653450251514 x 12 x 147310628556403

21、85516 x 14 x 16900072006270441518 x 16 x 181100097608465616520 x 18 x 20142001218511120796022 x 20 x 22168001600514130964526 x 24 x 262500023000螺栓阀盖旋启式止回阀全开状态下的流量系数 CvBolted CapSwing Check Valves FULL OPEN Cv阀门通径Valve Size压力等级Pressure Class150300600900150011/2636397214216813911121/221727522733563922

22、4635831547167404996055646141419921334162315208296123403359250810572057205440406912786085447045631614104161946498401613800138001291218134201302920167081627619540243338436672305455654652螺栓阀帽截止阀全开状态下的流量系数 CvBolted BonnetGlobe Valves FULL OPEN Cv压力等级Pressure Class150300600900阀门塞形塞形塞形塞形通径或V形或V形或V形或Valve

23、Size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Plug orV-PortPlug orV-PortPlug orV-PortPlug orBallDiscBallDiscBallDiscBallDiscDiscDiscDisc17 223232123243404340434021/ 270707031009210092100929041851701851701851701705297273644040544040544040588107458107457801012601150126012189018901810压力密封提升式阀瓣止回阀全开状态下的流量系数 CvPressur

24、e SealTilting Disc Check Valves FULL OPEN Cv阀门通径Valve Size压力等级Pressure Class9001500250021/2958060314613294426823014666275363558106294062710172214651020122420211014201429552550177516394533952355184900436530252062755465370524929580605465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 CvPressure SealVenturi Tilting Disc Che

25、ck Valves FULL OPEN Cv阀门通径Valve Size压力等级Pressure Class1503006008 x 6 x 810 x 8 x 1012 x 10 x 1214 x 12 x 1416 x 14 x 1618 x 16 x 1820 x 18 x 2022 x 20 x 2256595515502175266035504410565048084513201900229530553930492032056592012751598212027253335球形止回阀，截止止回阀，提升式止回阀的流量特性曲线Characteristic Flow Curves for Globe Stop, Stop-Check, Lift-Check Valves小于全开状态的估计流量系数 CvEstimating Cv For Less Than Fully Open Valves1111 f* *4 - -udglLIWJ證 dA-EAM