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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 a given
2、 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，单位：PSId
3、p=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Q=flow
4、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 or fla
5、shing. 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?解：采
6、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 same
7、 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 a
8、 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 smalle
9、st 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)Sat50060070080090010
10、00110010020030040050060070080090010001100120013001400160018002000250030004000500060001.971.461.211.060.9500.8650.8010.7470.7010.6620.6280.5980.5700.5452.201.611.301.110.9790.8952.321.681.381.191.060.9600.8800.8150.7590.7100.6700.6290.5900.5592.441.771.461.261.121.020.9410.8750.8210.7730.7320.6950.66
11、20.6330.580.540.500.410.310.170.160.162.541.851.521.321.181.080.9940.9260.8700.8160.7810.7450.7100.6830.630.590.550.480.420.320.240.192.641.951.601.381.231.131.040.9720.9140.8650.8230.7850.7520.7230.670.630.590.520.460.380.320.282.742.001.651.431.281.171.081.010.9550.9170.8720.8130.7890.7520.700.660
12、.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: (fp
13、s) = 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:W
14、hat 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)22
15、5 (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范围内：When determ
18、ining 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 Che
19、ck Valves - 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 1.83.14.97.112.628.350.378.5113.1137.9182.7233.7291.0424.5671.9969.01.83.14.97.112.628.350.37
20、8.5113.1137.9182.7227.0283.5424.5672.0942.01.83.17.112.628.348.774.7108.4130.2170.9213.8261.6380.1590.9851.21.83.14.96.511.826.044.271.0100.0117.91.52.84.06.010.322.738.560.084.5101.6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SEAT PORT AREA FOR PRESSURE SEAL GATE,GLOBE, TILT DISC CHECK VALVES (in2)阀门通径Valve S
21、ize压力等级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-GLO
22、BEVALVES (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 Class150300600900150011/2221/2345681012
23、1416182024303616530749071013002090311057208935133501627521560287203576052165862351295001653074907101300311057208935133501627521560278903484051050847651258251653074907101300311055408495128001537029170262703214046710755301142506501220285050257850114751391013827040060010701600250043756840998012000图1螺栓阀
24、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 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 Class6009001500250021/23468101214161820243505259252150377557508600102751342517200209503085035045085019
25、25357552507550915011950155751920027675275415730167529254550657078901032513425168252415019027546011001970313045355500721092151145016575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
26、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压力等级Pressure Class15030060090
27、0150011/2221/2346810121416182024306314221735671614142961572078601041613800134201670833384545566316827539274019922340572085441946413800130291627636672546529713922724649913343359544070459840129121954035860516232508406963161113155641520螺栓阀帽截止阀全开状态下的流量系数CvBolted BonnetGlobe Valves FULL OPEN Cv阀门通径Valve
28、Size压力等级Pressure Class150300600900塞形或球形阀瓣Plug orBallDiscV形端口阀瓣V-PortDisc塞形或球形阀瓣Plug orBallDiscV形端口阀瓣V-PortDisc塞形或球形阀瓣Plug orBallDiscV形端口阀瓣V-PortDisc塞形或球形阀瓣Plug orBallDisc11/2221/23456810122343701001852974408101260189040921702734057451150234370100185440810126018902140921704057452343701001854407801810
29、409217040590170压力密封提升式阀瓣止回阀全开状态下的流量系数Cv Pressure SealTilting Disc Check Valves FULL OPEN Cv阀门通径Valve Size压力等级Pressure Class9001500250021/2346810121416182024951462686271062172224202955394549006275929580132230536940146521102550339543655465806060941463556271020142017752355302537055465压力密封缩喉管提升式阀瓣止回阀全开状
30、态下的流量系数Cv Pressure SealVenturi Tilting Disc Check 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
31、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 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 Li
32、ft-Check Valves FULL OPEN Cv阀门通径Valve Size压力等级Pressure Class9001500250021/234681012149010519545580012501820220565951703956951085158045651052654707501100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阀门通径Valve Size压力等级Pressure Class60090015
33、002500810121416182024202530254600430076507325118001645017502725382536506000582591251350017502725382536506000582591251350011751875265040753775662562259050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 val
34、ves only. Flow coefficients at other than fully open may be approximated by 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 Cl
35、ass 900 Pacific pressure seal globe valve 1/4 open?图3Y形球形止回阀，截止止回阀和提升式止回阀Figure 3Y-Globe Stop, Stop-Check andLift-Check Valves压力密封缩喉管球形止回阀，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 Venturi Globe Stop,Stop-Check and Lift-Check Valves FULL OPEN Cv阀门通径Valve Size压力等级Pressure Class900150025008 x 6 x 810 x 8
36、 x 1012 x 10 x 1214 x 12 x 1416 x 14 x 16450770121517752125390690105515502604657451070压力密封缩喉管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Cv Pressure Seal Venturi Y-Globe Stop,Stop-Check and Lift-Check 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
37、 14 x 1618 x 16 x 1820 x 18 x 2022 x 20 x 2216 x 24 x 26110019252875437540757250695011200158501000167526003650345057005525867512825100016752600365034505700552586751282565011251775252538753575630059258600解：从上列流量系数表中得到，DN300，压力等级Class 900截止阀在全开状态下的Cv是1820。 SOLUTION:From the flow coefficient table above, the fully open Cv for a 12 inch, Class 900 globe valve is 1820.查询图2，全开状态的1/4时阀门的比率是52%.Consulting Figure 2, the percent of fully open Cv at 1/4 valve open is 52%. 因此计算1/4全开的流量系数Cv为：0.52 x 1820 = 946.The Cv at 1/4 open is then computed as:0.52 x 1820 = 946.