1、阀门流量计算方法 发布时间：2010-1-29 来源地：shhbqfm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
2、, the more flow a valve can pass with 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
3、 LBS/HR (Steam 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 ft3/lb.(downstream of valve)公式 22. 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 th
4、rough 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 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
5、 that will have less than a 5 PSI pressure drop in 900oF, 1200 PSI steam service at 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
6、。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 SteamFORMULA 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 = pressur
7、e drop 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-
8、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. 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/小时的水的 (下游)For Water (Downstream)温度( oF)Temperature (oF)100 200 300 400 500
9、600所有压力等级AllPressures0.127 0.129 0.132 0.137 0.143 0.154蒸汽的 (下游)For Steam (Downstream)温度( oF)Temperature (oF)压力PSIG PressurePSIGSat 500 600 700 800 900 1000 110010020030040050060070080090010001100120013001400160018002000250030004000500060001.971.461.211.060.9500.8650.8010.7470.7010.6620.6280.5980.57
10、00.5452.201.611.301.110.9790.8952.321.681.381.191.060.9600.8800.8150.7590.7100.6700.6290.5900.5592.441.771.461.261.121.020.9410.8750.8210.7730.7320.6950.6620.6330.580.540.500.410.310.170.160.162.541.851.521.321.181.080.9940.9260.8700.8160.7810.7450.7100.6830.630.590.550.480.420.320.240.192.641.951.6
11、01.381.231.131.040.9720.9140.8650.8230.7850.7520.7230.670.630.590.520.460.380.320.282.742.001.651.431.281.171.081.010.9550.9170.8720.8130.7890.7520.700.660.620.550.490.420.360.322.842.071.711.471.331.221.121.050.990.940.900.860.830.790.740.690.650.580.520.440.390.35压降是多少？What is the pressure drop th
12、rough a 14“ Class 900 pressure seal gate valve with 400oF water, 1500 PSIG, and 5,000,000 lbs/hr flow rate?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)阀座端口流速计算Calculating Seat Port Velocity下列公
13、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: (fps) = F( )225A流量(加仑/分钟): 流速: (英尺/秒)= 0.32QA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)压力等级Pressure Class阀门通径Valve Size150 3
14、00 600 900 150011/2221/23468101214161.83.14.97.112.628.350.378.5113.1137.9182.71.83.14.97.112.628.350.378.5113.1137.9182.71.83.17.112.628.348.774.7108.4130.2170.91.83.14.96.511.826.044.271.0100.0117.91.52.84.06.010.322.738.560.084.5101.6Flow (GPM): vel: (fps) = 0.32QA在此：Where:F = 流量(磅/小时)F = flow (l
15、bs/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:What is the seat port velocity in a 12“ Figure 58809 (Class 900) check valve with
16、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( )2 = 90,000 (1.61)2 = 118.8 英尺/秒1820243036 233.7291.0424.5671.9969.0227.0283.5424.5672.0942.0
17、213.8261.6380.1590.9851.2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Pressure Class阀门通径Valve Size600 900 1500 250021/23468101214161820245.45.49.623.239.961.088.7173.8310.255.95.910.321.737.758.480.597.2125.2156.7198.0287.33.34.98.31
18、8.931.948.769.082.5108.4137.9170.9247.52.43.65.912.621.734.547.258.276.697.2117.9170.9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-GLOBEVALVES (in2)阀门通径Valve Size压力等级Pressure Class25A 25 (78.5)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
19、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 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( )2
20、25A=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半。900 1500 250081012141618202439.961.986.686.6135.4135.4198.1302.639.961.986.686.6135.4135.
21、4198.1302.627.242.860.186.686.6135.4135.4198.1For 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
22、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 determining 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
23、 to 120 PS Tilt Disc Check Valves - 55 to 200 PS Stop Check Valves - 40 to 180PS Y- Stop Check Valves - 148 to 200 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Pressure Class阀门通径Valve Size150 300 600 900 150011/2221/2165307490165307490165307490138270400螺栓阀盖旋启式止回阀全开状态下的流量系数 CvBolted Ca
24、pSwing Check Valves FULL OPEN Cv压力等级Pressure Class阀门通径Valve Size150 300 600 900 150011/2221/2631422176316827597139227111345681012141618202430367101300209031105720893513350162752156028720357605216586235129500710130031105720893513350162752156027890348405105084765125825710130031105540849512800153702917
25、0262703214046710755301142506501220285050257850114751391060010701600250043756840998012000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 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压力等级Pressure Class阀门通径Valve Size60
26、0 900 1500 2500346810121416182024303567161414296157207860104161380013420167083338454556392740199223405720854419464138001302916276366725465224649913343359544070459840129121954035860516232508406963163155641520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 Class150 300 600 900阀门
27、通径Valve Size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 orBallDisc11/2221/23456234370100185297440409217027340523437010018544021409217040523437010018544040921704059017021/234681012141618202435052592521503775575086001
28、0275134251720020950308503504508501925357552507550915011950155751920027675275415730167529254550657078901032513425168252415019027546011001970313045355500721092151145016575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Pressure Class阀门通径Valve Size600 900 1500 25008 x 6 x 810 x 8
29、 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 2615702795448573109000110001420016800250001385238540656285720097601218516005230001185215534505640627084651112014130815143025153855441561657960964581012810126018907451150810126018907457801810压力密封提升式阀瓣止回阀全开状态下的流量系数
30、Cv Pressure SealTilting Disc Check Valves FULL OPEN Cv压力等级Pressure Class阀门通径Valve Size900 1500 250021/2346810121416182024951462686271062172224202955394549006275929580132230536940146521102550339543655465806060941463556271020142017752355302537055465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 Cv Pressure SealVenturi Til
31、ting Disc Check Valves FULL OPEN Cv压力等级Pressure Class阀门通径Valve Size150 300 6008 x 6 x 810 x 8 x 1012 x 10 x 125659551550480845132032056592014 x 12 x 1416 x 14 x 1618 x 16 x 1820 x 18 x 2022 x 20 x 22217526603550441056501900229530553930492012751598212027253335球形止回阀，截止止回阀，提升式止回阀的流量特性曲线Characteristic F
32、low 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 Lift-Check Valves FULL OPEN C
33、v压力等级Pressure Class阀门通径Valve Size900 1500 2500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压力等级Pressure Class阀门通径Valve Size900 1500 250021/234681012149
34、010519545580012501820220565951703956951085158045651052654707501100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Pressure Class阀门通径Valve Size600 900 1500 250081012141618202420253025460043007650732511800164501750272538253650600058259
35、1251350017502725382536506000582591251350011751875265040753775662562259050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 approximated by use
36、of the characteristic flow curves for tilting disc check and globe valves. Gate valves are not recommended for throttling service.8 x 6 x 810 x 8 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-Gl
37、obe Stop,Stop-Check and Lift-Check Valves FULL OPEN Cv压力等级Pressure Class阀门通径Valve Size600 900 1500 25008 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 2216 x 24 x 26110019252875437540757250695011200158501000167526003650345057005525867512825100016752600365034
38、505700552586751282565011251775252538753575630059258600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：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 900 Pacific pressure seal globe valve 1/4 open?0.52 x 1820 = 946.The Cv at 1/4 open is then computed as:0.52 x 1820 = 946
