阀门流量计算方法

1、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 15 oC 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 15 o C 的水。Valve coefficient (Cv) is a number which represents a valve's ability to pass flow. The bigger the Cv,the more flow a v

2、alve can pass with a given pressure drop. A Cv of 1 means a valve will pass 1 gallon per minute (gpm) of 60 oF 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 o 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 (Ste

3、am or Water)在此：Where: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 (downstream of valve)3/lb.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

4、 in PSISg= 比重Sg= specific 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。For compressible fluids, where pressure drop exceeds half the inlet pressure.b. 对于不可压缩性流体，如果压降产生空穴或闪蒸。For non-compressi

5、ble fluids, where pressure drop causes cavitation or flashing.c. 对于双相流体，如蒸汽 -水混合流体。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400 oF ，压力为 1500 PSIG ，流速为5,000,000磅 /小时的压降是多少？What is the pressure drop through a 14" Class 900 pressure seal gate valve

6、 with 4001500 PSIG, and 5,000,000 lbs/hr flow rate?解：采用公式1Solution: Use formula 1.o F water,F =5,000,000=0.137 ( 从水温为400 o F 的表中得到 )=0.137 (from chart for water at 400oF)Cv=9150 ( 来自本页 )Cv=9150 (from page 26)2.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，求压降。What is the pressure drop thro

7、ugh a 14"x12"x14" Class 900 Venturi pressure seal gate valve with the same conditions as example 1.解：采用公式1Solution: Use formula 1.Cv = 6285 ( 来自本页 )Cv = 6285 (from page 26)3.温度 900 oF, 压力 1200 PSI ，流速 500,000 磅/ 小时的蒸汽应用中压降小于5 PSI 的压力等级Class2500 闸阀的最小通径是多少？What is the smallest Class 25

8、00 gate valve that will have less than a 5 PSI pressure drop ino900 F, 1200 PSI steam service at a flow rate of 500,000 lbs/hr?Solution: Use formula 1.F =500,000=0.785( 来自 900 o F, 1200 PSIG蒸汽表 )=0.785(from chart for steam at 900o F, 1200 PSIG)= 2.24最接近的、较大的Cv 是 DN250 压力等级 Class 2500闸阀，其 Cv 是 3130 。

9、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 apressure drop less than 5 PSIG.水和蒸汽的备选特性Selected Properties of Water and Steam水的 (下游 )For Water (Downstream)温度 ( oF)所有压力等级Temperature (oF)All100200300400500600Pressures0.1270.1

10、290.1320.1370.1430.154蒸汽的 (下游 )For Steam (Downstream)压力温度 (o F)PSIGTemperature ( o F)PressureSat50060070080090010001100PSIG1001.972.202.322.442.542.642.742.842001.461.611.681.771.851.952.002.073001.211.301.381.461.521.601.651.714001.061.111.191.261.321.381.431.475000.9500.9791.061.121.181.231.281.33

11、6000.8650.8950.9601.021.081.131.171.227000.8010.8800.9410.9941.041.081.128000.7470.8150.8750.9260.9721.011.059000.7010.7590.8210.8700.9140.9550.9910000.6620.7100.7730.8160.8650.9170.9411000.6280.6700.7320.7810.8230.8720.9012000.5980.6290.6950.7450.7850.8130.8613000.5700.5900.6620.7100.7520.7890.8314

12、000.5450.5590.6330.6830.7230.7520.7916000.580.630.670.700.7418000.540.590.630.660.6920000.500.550.590.620.6525000.410.480.520.550.5830000.310.420.460.490.5240000.170.320.380.420.4450000.160.240.320.360.3960000.160.190.280.320.35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

13、formulas can be used to calculate seat portvelocity in any valve:F() 2流量 (磅/小时 ): 流速 : (英尺 /秒)=25AF() 2Flow (lbs/hr): vel: (fps) =25A0.32Q流量 (加仑 /分钟 ): 流速 : (英尺 /秒)=A0.32QFlow (GPM): vel: (fps) =A在此：Where:F = 流量 (磅/小时 )F = flow (lbs/hr)= 比容积的平方根= square root of specific volumeA = 阀座端口面积 ( 英寸 2)A=sea

14、t port area (in2 )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 oF，压力 200 PSIG的蒸汽，流速为 90,000 磅 /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 rate of90,000 lbs/hr of steam at 500o F and 200 PSIG?解：

15、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 2。Answer:From the steam tables is 1.61, and from the seat port area table A is 78.5 in2.F() 290,000 (1.61)流速 : (英尺 /秒)=25A25 (78.5)F() 290,000 (1.61)Vel (fps) =25A25 (78.5)2= 118.8英尺 /秒2= 118.8 fps例：DN300 型号 180 ( 压力等级150) 旋启式止回阀，流体介质为温度500 oF，压力 200 PSIG的蒸汽，流速

16、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 of90,000 lbs/hr of steam at 500oF and 200 PSIG?解：查表得为 1.61 ， A 为113.1 英寸 3.Answer:From the tables is 1.61 and A is 113.1 in3.F() 290,000 (1.61)2流速 : (英尺 /秒)= 82.5 英尺 /

17、秒25A25 (113.1)Vel (fps) =F() 2=90,000 (1.61)2= 82.5 fps25A25 (113.1)局限性LIMITATIONS流速公式在下列条件下无效：Velocity 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。For compressible fluids, where pressure drop exceeds half the inlet pressure.b. 对于不可压缩性流体，如果压降产生空穴或闪蒸。For non-compre

18、ssible fluids, where pressure drop causes cavitation or flashing.c. 对于双相流体，如蒸汽 -水混合流体。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围：When determining sizing for check valves, the optimum operating velocities should fall within theseranges:BB 旋启式止回阀： 55 至 115 或 135 至

19、 240 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 200BB Swing Check Valves - 55 to 115 or 135 to 240 BB Stop Check Valves - 40 to 120PS Tilt Disc Check Valves - 55 to 200 PS Stop Check Valves - 40 to 180 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&q

20、uot; FOR BOLTEDBONNET VALVES (in2 )压力等级阀门通径Pressure ClassValve Size150300600900150011/21.81.81.81.81.523.13.13.13.12.821/24.94.94.94.037.17.17.16.56.0412.612.612.611.810.3628.328.328.326.022.7850.350.348.744.238.51078.578.574.771.060.012113.1113.1108.4100.084.514137.9137.9130.2117.9101.616182.7182.7

21、170.918233.7227.0213.820291.0283.5261.624424.5424.5380.130671.9672.0590.936969.0942.0851.2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 DISC CHECK VALVES (in2 )压力等级阀门通径Pressure ClassValve Size600900150025002 1/25.45.93.32.435.45.94.93.649.610.38.35.9623.221.71

22、8.912.6839.937.731.921.71061.058.448.734.51288.780.569.047.21497.282.558.216125.2108.476.618173.8156.7137.997.220198.0170.9117.924310.25287.3247.5170.9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 )压力等级阀门通径Pressure ClassValve Size90015002500839.939.927.21061.961.942

23、.81286.686.660.11486.686.686.616135.4135.486.618135.4135.4135.420198.1198.1135.424302.6302.6198.1螺栓阀帽闸阀全开状态下的流量系数CvBolted BonnetGate Valves FULL OPEN Cv压力等级阀门通径Pressure ClassValve Size150300600900150011/2165165165138230730730727021/24904904904003710710710650600413001300130012201070520901600631103110

24、311028502500857205720554050254375108935893584957850684012133501335012800114759980141627516275153701391012000162156021560291701828720278902627020357603484032140245216551050467103086235847657553036129500125825114250图 1螺栓阀帽截止阀Figure 1Bolted BonnetGlobe Valves(1) 当开启度小于10% 时，不建议用于节流应用。(1) not recommende

25、d forthrottling at lessthan 10% Open.压力密封闸阀全开状态下的流量系数CvPressure SealGate Valves FULL OPEN Cv压力等级阀门通径Pressure ClassValve Size600900150025002 1/23503502751903525450415275492585073046062150192516751100837753575292519701057505250455031301286007550657045351410275915078905500161342511950103257210181720015

26、57513425921520209501920016825114502430850276752415016575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压力等级阀门通径Pressure ClassValve Size600900150025008 x 6 x 815701385118581510 x 8 x 10279523852155143012 x 10 x 12448540653450251514 x 12 x 14731062855640385516 x 14 x 169000720062704

27、41518 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压力等级阀门通径Pressure ClassValve Size15030060090015001 1/263639721421681391112 1/221727522733563922463583154716740499605564614

28、1419921334162315208296123403359250810572057205440406912786085447045631614104161946498401613800138001291218134201302920167081627619540243338436672305455654652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 Size球形端口球形端口球形端口球形阀瓣阀瓣阀瓣阀

29、瓣阀瓣阀瓣阀瓣Plug orV-PortPlug orV-PortPlug orV-PortPlug orBallDiscBallDiscBallDiscBallDiscDiscDiscDisc1 1/22323212324340434043402 1/270707031009210092100929041851701851701851701705297273644040544040544040588107458107457801012601150126012189018901810压力密封提升式阀瓣止回阀全开状态下的流量系数CvPressure SealTilting Disc Check

30、Valves FULL OPEN Cv压力等级阀门通径Pressure ClassValve Size9001500250021/2958060314613294426823014666275363558106294062710172214651020122420211014201429552550177516394533952355184900436530252062755465370524929580605465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 Check Valves FULL OPEN Cv压力等级

31、阀门通径Pressure ClassValve Size1503006008 x 6 x 856548032010 x 8 x 1095584556512 x 10 x 121550132092014 x 12 x 1421751900127516 x 14 x 1626602295159818 x 16 x 1835503055212020 x 18 x 2044103930272522 x 20 x 22565049203335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, Li

32、ft-Check Valves小于全开状态的估计流量系数CvEstimating Cv For Less Than Fully Open Valves图 2球形止回阀，截止止回阀和提升式止回阀Figure 2Globe Stop, Stop-Check andLift-Check Valves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CvPressure Seal T-Globe Stop,Stop-Check and Lift-Check Valves FULL OPEN Cv压力等级阀门通径Pressure ClassValve Size90015002500

33、21/290654531059565419517010564553952658800695470101250108575012182015801100142205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CvPressure Seal Y-Globe Stop,Stop-Check and Lift-Check Valves FULL OPEN Cv压力等级阀门通径Pressure ClassValve Size60090015002500820251750175011751030252725272518751246003825382526501443003650

34、365040751676506000600037751873255825582566252011800912591256225241645013500135009050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算。不建议将闸阀用在节流应用中。The flow coefficient (Cv) listed in the tables apply to fully open valves only. Flow coefficients at other than fully open may be approximatedby use of the characteristic flow curves for tilting disc check and globe valves. Gate valves are not recommended for throttling service.例：DN300，压力等级Class 900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:What is the Cv of a 12 inch Class 90