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 bigger the Cv, the more flow a valve can pass with

2、a given pressure drop. A Cv of 1 means a valve will pass 1 gallon per minute (gpm) of 60oF water with a pressure drop (dp) of 1 PSI across the valve. A Cv of 350 means a valve will pass 350 gpm of 60oF 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)在此：Where:dp=压降，

3、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 ft3/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=specific gravityQ=流速，单位：加伦/分钟

4、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-compressible fluids, where pressure drop causes cavitation o

5、r 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400oF，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 with 400oF water, 1500 PSIG, and 5,000,000 lbs/hr flow rate?

6、解：采用公式1Solution: Use formula 1. F=5,000,000=0.137 (从水温为400oF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 through a 14x12x14 Class 900 Venturi pressure seal gate valve with the sa

7、me 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900oF, 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Class 2500闸阀的最小通径是多少？What is the smallest Class 2500 gate valve that will have less than a 5 PSI pressure drop in 900oF, 1200 PSI steam service at

8、a flow rate of 500,000 lbs/hr?解：采用公式1Solution: Use formula 1. F=500,000=0.785 (来自900oF, 1200 PSIG蒸汽表)=0.785 (from chart for steam at 900oF, 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。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 small

9、est 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)For Water (Downstream)所有压力等级AllPressures温度(oF)Temperature (oF)1002003004005006000.1270.1290.1320.1370.1430.154蒸汽的(下游)For Steam (Downstream)压力PSIG PressurePSIG温度(oF)Temperature (oF)Sat5006007008009001

10、000110010020030040050060070080090010001100120013001400160018002000250030004000500060001.971.461.211.060.9500.8650.8010.7470.7010.6620.6280.5980.5700.5452.201.611.301.110.9790.8952.321.681.381.191.060.9600.8800.8150.7590.7100.6700.6290.5900.5592.441.771.461.261.121.020.9410.8750.8210.7730.7320.6950.6

11、620.6330.580.540.500.410.310.170.160.162.541.851.521.321.181.080.9940.9260.8700.8160.7810.7450.7100.6830.630.590.550.480.420.320.240.192.641.951.601.381.231.131.040.9720.9140.8650.8230.7850.7520.7230.670.630.590.520.460.380.320.282.742.001.651.431.281.171.081.010.9550.9170.8720.8130.7890.7520.700.66

12、0.620.550.490.420.360.322.842.071.711.471.331.221.121.050.990.940.900.860.830.790.740.690.650.580.520.440.390.35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 formulas can be used to calculate seat portvelocity in any valve:流量(磅/小时): 流速: (英尺/秒)= F()225AFlow (lbs/hr): vel: (f

13、ps) = F()225A流量(加仑/分钟): 流速: (英尺/秒)= 0.32QAFlow (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=square root of specific volumeA=阀座端口面积 (英寸2)A=seat 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:

14、What is the seat port velocity in a 12 Figure 58809 (Class 900) check valve with a flow rate of 90,000 lbs/hr of steam at 500 oF and 200 PSIG?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2。Answer:From the steam tables is 1.61, and from the seat port area table A is 78.5 in2.流速: (英尺/秒)= F()225A=90,000 (1.61)2

15、25 (78.5)= 118.8 英尺/秒Vel (fps) = F()225A=90,000 (1.61)225 (78.5)= 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500oF，压力200 PSIG的蒸汽，流速为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 500oF and 200

16、 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.流速: (英尺/秒)= F()225A=90,000 (1.61)225 (113.1)= 82.5英尺/秒Vel (fps) = F()225A=90,000 (1.61)225 (113.1)= 82.5 fps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

17、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-compressible 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 determinin

18、g sizing for check valves, the optimum operating velocities should fall within these ranges:BB旋启式止回阀：55 至115或135至240BB截止止回阀：40 至120 PS提升式阀瓣止回阀：55至200 PSY形止回阀：148 至200 BB Swing Check Valves - 55 to 115 or 135 to 240BB Stop Check Valves - 40 to 120 PS Tilt Disc Check Valves - 55 to 200 PS Stop Check V

19、alves - 40 to 180PS 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 (in2)阀门通径Valve Size压力等级Pressure Class150300600900150011/2221/23468101214161820243036 1.83.14.97.112.628.350.378.5113.1137.9182.7233.7291.0424.5671.9969.01.83.14.97.112.628.350.378.51

20、13.1137.9182.7227.0283.5424.5672.0942.01.83.17.112.628.348.774.7108.4130.2170.9213.8261.6380.1590.9851.21.83.14.96.511.826.044.271.0100.0117.91.52.84.06.010.322.738.560.084.5101.6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SEAT PORT AREA FOR PRESSURE SEAL GATE,GLOBE, TILT DISC CHECK VALVES (in2)阀门通径Valve Size压

21、力等级Pressure Class6009001500250021/23468101214161820245.45.49.623.239.961.088.7173.8310.255.95.910.321.737.758.480.597.2125.2156.7198.0287.33.34.98.318.931.948.769.082.5108.4137.9170.9247.52.43.65.912.621.734.547.258.276.697.2117.9170.9阀座端口面积(英寸2)适用于压力密封Y形截止阀SEAT PORT AREA FOR PRESSURE SEAL Y-GLOBEVA

22、LVES (in2)阀门通径Valve Size压力等级Pressure Class9001500250081012141618202439.961.986.686.6135.4135.4198.1302.639.961.986.686.6135.4135.4198.1302.627.242.860.186.686.6135.4135.4198.1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Pressure Class150300600900150011/2221/23456810121416

23、182024303616530749071013002090311057208935133501627521560287203576052165862351295001653074907101300311057208935133501627521560278903484051050847651258251653074907101300311055408495128001537029170262703214046710755301142506501220285050257850114751391013827040060010701600250043756840998012000图1螺栓阀帽截止阀

24、Figure 1Bolted BonnetGlobe Valves(1)当开启度小于10%时，不建议用于节流应用。(1) not recommended 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阀门通径Valve Size压力等级Pressure Class6009001500250021/234681012141618202435052592521503775575086001027513425172002095030850350450850192535

25、7552507550915011950155751920027675275415730167529254550657078901032513425168252415019027546011001970313045355500721092151145016575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 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 2226 x 24 x 26157027954485731090001100014200168002500013852385406562857200976012185160052300011852155345056406270846511120141308151430251538554415616579609645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