閥門流量計(jì)算

1、閥門流量計(jì)算方法 發(fā)表于： 2010-1-29 9:39:55 如何使用流量系數(shù)How to use Cv閥門流量系數(shù)(Cv)是表示閥門通過流體能力的數(shù)值。Cv越大，在給定壓降下閥門能夠通過的流體就越多。Cv值1表示當(dāng)通過壓降為1 PSI時(shí)，閥門每分鐘流過1加侖15oC的水。Cv值350表示當(dāng)通過壓降為1 PSI時(shí)，閥門每分鐘流過350加侖15oC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

2、 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/小時(shí)(蒸汽或水)FLOW RATE LBS/HR (Steam or

3、Water)在此：Where:dp=壓降，單位：PSIdp=pressure drop in PSIF=流速，單位：磅/小時(shí)F=flow rate in lbs./hr.=比容積的平方根，單位：立方英尺/磅(閥門下游)=square root of a specific volume in ft3/lb.(downstream of valve)公式2FORMULA 2流速：加倫/分鐘(水或其它液體)FLOW RATE GPM (Water or other liquids)在此：Where:dp=壓降，單位：PSIdp=pressure drop in PSISg=比重Sg=specific

4、 gravityQ=流速，單位：加倫/分鐘Q=flow rate in GPM局限性LIMITATIONS上列公式在下列條件下無(wú)效：Above formulas are not valid under the following conditions:a. 對(duì)于可壓縮性流體，如果壓降超過進(jìn)口壓力的一半。For compressible fluids, where pressure drop exceeds half the inlet pressure. b. 對(duì)于不可壓縮性流體，如果壓降產(chǎn)生空穴或閃蒸。For non-compressible fluids, where pressure d

5、rop causes cavitation or flashing. c. 對(duì)于雙相流體，如蒸汽-水混合流體。For dual-phase flow such as steam-water mixtures. 例子EXAMPLE1. 通過DN350, 壓力等級(jí)Class 900的壓力密封閘閥，水溫400oF，壓力為1500 PSIG，流速為5,000,000磅/小時(shí)的壓降是多少？What is the pressure drop through a 14" Class 900 pressure seal gate valve with 400oF water, 1500 PSIG,

6、and 5,000,000 lbs/hr flow rate?解：采用公式1Solution: Use formula 1. F=5,000,000=0.137 (從水溫為400oF的表中得到)=0.137 (from chart for water at 400oF)Cv=9150 (來(lái)自本頁(yè))Cv=9150 (from page 26) 2. DN350 x DN300 x DN350，壓力等級(jí)Class 900縮喉管壓力密封閘閥，其它條件與例1相同，求壓降。What is the pressure drop through a 14"x12"x14"

7、; 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 (來(lái)自本頁(yè))Cv = 6285 (from page 26)3. 溫度900oF, 壓力1200 PSI，流速500,000磅/小時(shí)的蒸汽應(yīng)用中壓降小于5 PSI的壓力等級(jí)Class 2500閘閥的最小通徑是多少？What is the smallest Class 2500 gate valve that will have less than a

8、 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 (來(lái)自900oF, 1200 PSIG蒸汽表)=0.785 (from chart for steam at 900oF, 1200 PSIG)= 2.24 最接近的、較大的Cv是DN250壓力等級(jí)Class 2500閘閥，其Cv是3130。這里是壓降小于5 PSIG的最小的閥門。The closest higher

9、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.水和蒸汽的備選特性Selected Properties of Water and Steam水的(下游)For Water (Downstream)所有壓力等級(jí)AllPressures溫度(oF)Temperature (oF)1002003004005006000.1270.1290.1320.1370.1430.154 蒸汽的(下游)For Ste

10、am (Downstream)壓力PSIG PressurePSIG溫度(oF)Temperature (oF)Sat5006007008009001000110010020030040050060070080090010001100120013001400160018002000250030004000500060001.971.461.211.060.9500.8650.8010.7470.7010.6620.6280.5980.5700.5452.201.611.301.110.9790.8952.321.681.381.191.060.9600.8800.8150.7590.7100.

11、6700.6290.5900.5592.441.771.461.261.121.020.9410.8750.8210.7730.7320.6950.6620.6330.580.540.500.410.310.170.160.162.541.851.521.321.181.080.9940.9260.8700.8160.7810.7450.7100.6830.630.590.550.480.420.320.240.192.641.951.601.381.231.131.040.9720.9140.8650.8230.7850.7520.7230.670.630.590.520.460.380.3

12、20.282.742.001.651.431.281.171.081.010.9550.9170.8720.8130.7890.7520.700.660.620.550.490.420.360.322.842.071.711.471.331.221.121.050.990.940.900.860.830.790.740.690.650.580.520.440.390.35閥座端口流速計(jì)算Calculating Seat Port Velocity下列公式可以用來(lái)計(jì)算任何閥門的閥座流速：The following formulas can be used to calculate seat po

13、rtvelocity in any valve:流量(磅/小時(shí)): 流速: (英尺/秒)= F()225AFlow (lbs/hr): vel: (fps) = F()225A流量(加侖/分鐘): 流速: (英尺/秒)= 0.32QAFlow (GPM): vel: (fps) = 0.32QA 在此：Where:F=流量(磅/小時(shí))F=flow (lbs/hr)=比容積的平方根=square root of specific volumeA=閥座端口面積 (英寸2)A=seat port area (in2)Q=流量 (加侖/分鐘)Q=flow (gpm)例：DN300型號(hào)5880

14、9 (壓力等級(jí)Class 900)止回閥，流體介質(zhì)為溫度500 oF，壓力200 PSIG的蒸汽，流速為90,000磅/小時(shí)，求閥座端口的流速？ Example:What is the seat port velocity in a 12" Figure 58809 (Class 900) check valve with a flow rate of 90,000 lbs/hr of steam at 500 oF and 200 PSIG?解：從蒸汽表得為1.61，從閥座端口面積表A得閥座端口面積為78.5英寸2。Answer:From the steam tables is 1

15、.61, and from the seat port area table A is 78.5 in2.流速: (英尺/秒)= F()225A=90,000 (1.61)225 (78.5)= 118.8 英尺/秒Vel (fps) = F()225A=90,000 (1.61)225 (78.5)= 118.8 fps例：DN300型號(hào)180 (壓力等級(jí)150)旋啟式止回閥，流體介質(zhì)為溫度500oF，壓力200 PSIG的蒸汽，流速為90,000磅/小時(shí)，求閥座端口流速？Example:What is the seat port velocity in a 12" Figure

16、180 (Class 150) Swing Check Valve with a flow rate of 90,000 lbs/hr of steam at 500oF and 200 PSIG?解：查表得為1.61，A為 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

17、列條件下無(wú)效：Velocity formulas are not valid under the following conditions:a. 對(duì)于可壓縮性流體，如果壓降超過進(jìn)口壓力的一半。For compressible fluids, where pressure drop exceeds half the inlet pressure. b. 對(duì)于不可壓縮性流體，如果壓降產(chǎn)生空穴或閃蒸。For non-compressible fluids, where pressure drop causes cavitation or flashing. c. 對(duì)于雙相流體，如蒸汽-水混合流體。F

18、or dual-phase flow such as steam-water mixtures. 注意NOTE在確定止回閥通徑時(shí)，最適宜的工作流速應(yīng)該位于這些范圍內(nèi)：When determining sizing for check valves, the optimum operating velocities should fall within these ranges:BB旋啟式止回閥：55 至115或135至240BB截止止回閥：40 至120 PS提升式閥瓣止回閥：55至200 PSY形止回閥：148 至200 BB Swing Check Valves - 55 to 115 o

19、r 135 to 240BB Stop Check Valves - 40 to 120 PS Tilt Disc Check Valves - 55 to 200 PS Stop Check Valves - 40 to 180PS Y- Stop Check Valves - 148 to 200  閥座端口面積“A”(英寸2)適用于螺栓閥帽閥門SEAT PORT AREA "A" FOR BOLTEDBONNET VALVES (in2)閥門通徑Valve Size壓力等級(jí)Pressure Class150300600900150011/2221/23468

20、101214161820243036 1.83.14.97.112.628.350.378.5113.1137.9182.7233.7291.0424.5671.9969.01.83.14.97.112.628.350.378.5113.1137.9182.7227.0283.5424.5672.0942.01.83.17.112.628.348.774.7108.4130.2170.9213.8261.6380.1590.9851.21.83.14.96.511.826.044.271.0100.0117.91.52.84.06.010.322.738.560.084.5101.6 

21、;閥座端口面積(英寸2)適用于壓力密封閘閥，截止閥，提升式閥瓣止回閥SEAT PORT AREA FOR PRESSURE SEAL GATE,GLOBE, TILT DISC CHECK VALVES (in2)閥門通徑Valve Size壓力等級(jí)Pressure Class6009001500250021/23468101214161820245.45.49.623.239.961.088.7173.8310.255.95.910.321.737.758.480.597.2125.2156.7198.0287.33.34.98.318.931.948.769.082.5108.4137.9

22、170.9247.52.43.65.912.621.734.547.258.276.697.2117.9170.9 閥座端口面積(英寸2)適用于壓力密封Y形截止閥SEAT PORT AREA FOR PRESSURE SEAL Y-GLOBEVALVES (in2)閥門通徑Valve Size壓力等級(jí)Pressure Class9001500250081012141618202439.961.986.686.6135.4135.4198.1302.639.961.986.686.6135.4135.4198.1302.627.242.860.186.686.6135.4135.419

23、8.1螺栓閥帽閘閥全開狀態(tài)下的流量系數(shù)CvBolted BonnetGate Valves FULL OPEN Cv閥門通徑Valve Size壓力等級(jí)Pressure Class150300600900150011/2221/234568101214161820243036165307490710130020903110572089351335016275215602872035760521658623512950016530749071013003110572089351335016275215602789034840510508476512582516530749071013003110

24、55408495128001537029170262703214046710755301142506501220285050257850114751391013827040060010701600250043756840998012000 圖1螺栓閥帽截止閥Figure 1Bolted BonnetGlobe Valves(1)當(dāng)開啟度小于10%時(shí)，不建議用于節(jié)流應(yīng)用。(1) not recommended forthrottling at lessthan 10% Open. 壓力密封閘閥全開狀態(tài)下的流量系數(shù)CvPressure SealGate Valves FULL

25、OPEN Cv閥門通徑Valve Size壓力等級(jí)Pressure Class6009001500250021/2346810121416182024350525925215037755750860010275134251720020950308503504508501925357552507550915011950155751920027675275415730167529254550657078901032513425168252415019027546011001970313045355500721092151145016575 壓力密封縮喉管閘閥全開狀態(tài)下的流量系數(shù)CvPre

26、ssure SealVenturi Gate Valves FULL OPEN Cv閥門通徑Valve Size壓力等級(jí)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 26157027954485731090001100014200168002500013852385406562857200976012185160052300011852155345056406270846511120

27、141308151430251538554415616579609645 螺栓閥蓋旋啟式止回閥全開狀態(tài)下的流量系數(shù)CvBolted CapSwing Check Valves FULL OPEN Cv閥門通徑Valve Size壓力等級(jí)Pressure Class150300600900150011/2221/2346810121416182024306314221735671614142961572078601041613800134201670833384545566316827539274019922340572085441946413800130291627636672546

28、529713922724649913343359544070459840129121954035860516232508406963161113155641520 螺栓閥帽截止閥全開狀態(tài)下的流量系數(shù)CvBolted BonnetGlobe Valves FULL OPEN Cv閥門通徑Valve Size壓力等級(jí)Pressure Class150300600900塞形或球形閥瓣P(guān)lug orBallDiscV形端口閥瓣V-PortDisc塞形或球形閥瓣P(guān)lug orBallDiscV形端口閥瓣V-PortDisc塞形或球形閥瓣P(guān)lug orBallDiscV形端口閥瓣V-PortDi

29、sc塞形或球形閥瓣P(guān)lug orBallDisc11/2221/23456810122343701001852974408101260189040921702734057451150234370100185440810126018902140921704057452343701001854407801810409217040590170 壓力密封提升式閥瓣止回閥全開狀態(tài)下的流量系數(shù)Cv Pressure SealTilting Disc Check Valves FULL OPEN Cv閥門通徑Valve Size壓力等級(jí)Pressure Class9001500250021/234

30、6810121416182024951462686271062172224202955394549006275929580132230536940146521102550339543655465806060941463556271020142017752355302537055465 壓力密封縮喉管提升式閥瓣止回閥全開狀態(tài)下的流量系數(shù)Cv Pressure SealVenturi Tilting Disc Check Valves FULL OPEN Cv閥門通徑Valve Size壓力等級(jí)Pressure Class1503006008 x 6 x 810 x 8 x 1012 x

31、 10 x 1214 x 12 x 1416 x 14 x 1618 x 16 x 1820 x 18 x 2022 x 20 x 2256595515502175266035504410565048084513201900229530553930492032056592012751598212027253335球形止回閥，截止止回閥，提升式止回閥的流量特性曲線Characteristic Flow Curves for Globe Stop, Stop-Check, Lift-Check Valves小于全開狀態(tài)的估計(jì)流量系數(shù)CvEstimating Cv For Less Than Ful

32、ly Open Valves圖2球形止回閥，截止止回閥和提升式止回閥Figure 2Globe Stop, Stop-Check andLift-Check Valves壓力密封T形球形止回閥，截止止回閥和提升式止回閥閥全開狀態(tài)下的流量系數(shù)CvPressure Seal T-Globe Stop,Stop-Check and Lift-Check Valves FULL OPEN Cv閥門通徑Valve Size壓力等級(jí)Pressure Class9001500250021/234681012149010519545580012501820220565951703956951085158045

33、651052654707501100 壓力密封Y球形止回閥，截止止回閥和提升式止回閥閥全開狀態(tài)下的流量系數(shù)CvPressure Seal Y-Globe Stop,Stop-Check and Lift-Check Valves FULL OPEN Cv閥門通徑Valve Size壓力等級(jí)Pressure Class6009001500250081012141618202420253025460043007650732511800164501750272538253650600058259125135001750272538253650600058259125135001175187

34、5265040753775662562259050表中所列流量系數(shù)僅適用于全開狀態(tài)下的閥門。不是全開狀態(tài)的流量系數(shù)可以采用適用于提升式閥瓣止回閥和截止閥的流量特性曲線進(jìn)行估算。不建議將閘閥用在節(jié)流應(yīng)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 of the characteristic flow curves for tilting disc check and globe valves. Gate valves are not recommended for throttling service.例：DN300，壓力等級(jí)Class 900的美國(guó)太平洋壓力密封截止閥在開氣度為1/4時(shí)的流量系數(shù)是多少？EXAMPLE:What is the Cv of a 12 inch Class 900 Pacific p