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1、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 valve's ability to pass flow. The bigger the Cv,the more flow a valve can pass with a given p
2、ressure drop. A Cv of 1 means a valve will pass 1 gallon per minute (gpm) of 60 0F 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)FvV 63.5R匚63.5 vdp在此：Wh
3、ere: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)卜/、； = square root of a specific volume in ft 3/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)dp Sg or Cv - Q Sg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-compressibl
5、e 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°F ,压力为1500 PSIGoF water,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 v
6、alve with 4001500 PSIG, and 5,000,000 lbs/hr flow rate?解：采用公式1Solution: Use formula 1.F = 5,000,000同-=0.137(从水温为400 oF的表中得到)'底 =0.137 (from chart for water at 400 oF)Cv = 9150 (来自本页)Cv = 9150 (from page 26).=/ Fk x2 = / 5,000,000 X J 37VP _ 1 63,5 Cv ) " -63.5x9159 1=(1J8)2- 1.4 PSI2. DN350
7、 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 14"x12"x14" Class 900 Venturi pressure seal gate valvewith 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)dp = f x = (1= 2.9 PSII 63.5 X
8、6235 )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Class2500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 in900 oF, 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园 =0.785(来自 900oF, 1
9、200 PSIG 蒸汽表)0.785 (from chart for steam at 900oF, 1200 PSIG)2.24CvFvT_ _ 500t000 X .785 _ o*口公演=63.5X2.24 2759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 smallest valve with a pressure drop less tha
10、n 5 PSIG.水和蒸汽的备选特性Selected Properties of Water and Steam水的(下游)Fof 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v'V (下游)>'V For Steam (Downstream)压力温度(oF)PSIGTemperature ( oF)PressurePSIGSat500600700800900100011001001.972
11、.202.322.442.542.642.742.842001.461.611.681.771.851.952.002.073001.211.301.381.461.521.601.651.714001.061.111.191.261.321.381.431.475000.9500.9791.061.121.181.231.281.336000.8650.8950.9601.021.081.131.171.227000.8010.8800.9410.9941.041.081.128000.7470.8150.8750.9260.9721.011.059000.7010.7590.8210.87
12、00.9140.9550.9910000.6620.7100.7730.8160.8650.9170.9411000.6280.6700.7320.7810.8230.8720.9012000.5980.6290.6950.7450.7850.8130.8613000.5700.5900.6620.7100.7520.7890.8314000.5450.5590.6330.6830.7230.7520.7916000.580.630.670.700.7418000.540.590.630.660.6920000.500.550.590.620.6525000.410.480.520.550.5
13、830000.310.420.460.490.5240000.170.320.380.420.4450000.160.240.320.360.3960000.160.190.280.320.35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 formulas can be used to calculate seat portvelocity in any valve:流量（磅/小时）：流速：（英尺/秒尸F()225AFlow (lbs/hr): vel: (fps)=F( )225A0.32Q流量
14、（加仑/分钟）：流速：（英尺/秒尸AFlow (GPM): vel: (fps)=0.32QA在此：Where:F =流量(磅/小时)F = flow (lbs/hr)四=比容积的平方根= square root of specific volume2A =阀座端口面积(英寸2)A = seat port area (in 2)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 0F,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 se
15、at port velocity in a 12" Figure 58809 (Class 900) check valve with a flow rate of 90,000 lbs/hr of steam at 500°F and 200 PSIG?解：从蒸汽表得 由"为1.61 ,从阀座端口面积表 A得阀座端口面积为78.5英寸2Answer:From the steam tables is 1.61, and from the seat port area table A is 78.5 in 290,000 (1.61)=118.8英尺侬25A25 (
16、78.5)Vel (fps)=25A90,000 (1.61) 2=118.8 fps25 (78.5)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 500 oF and 200 PSIG?解:查表得VV为
17、1.61 , A为113.1英寸3Answer:From the tables is 1.61 and A is 113.1 in流速：（英尺/秒尸Vel (fps)=F()290,000 (1.61)=82.5英尺侬25AF()225A25 (113.1)90,000 (1.61)25 (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。For compressible fluids,
18、 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 determining sizing for check valves,
19、the optimum operating velocities should fall within these ranges:BB旋启式止回阀：55 VV至115 折或135 vT 至240BB截止止回阀：40 e 至120 /PS提升式阀瓣止回阀：55m至200 有PSY形止回阀：148 « 至200 «BB Swing Check Valves - 55 to 115 or 135 to 240BB Stop Check Valves - 40 to 120PS Tilt Disc Check Valves - 55to 200PS Stop Check Valve
20、s - 40 to 180PS Y- Stop Check Valves - 148to 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 (in 2)阀门通径Valve Size压力等级Pressure Class150300600900150011/21.81.81.81.81.523.13.13.13.12.821/24.94.9一4.94.037.17.17.16.56.0412.612.612.611.810.3628.328.328.326.022.7850.350.3
21、48.744.238.51078.578.574.771.060.012113.1113.1108.4100.084.514137.9137.9130.2117.9101.616182.7182.7170.9一一18233.7227.0213.8一一20291.0283.5261.6一一24424.5424.5380.1一一30671.9672.0590.9一一36969.0942.0851.2一一阀座端口面积(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 VALVE
22、S (in 2)阀门通径Valve Size压力等级Pressure Class6009001500250021/25.45.93.32.435.45.94.93.649.610.38.35.9623.221.718.912.6839.937.731.921.71061.058.448.734.51288.780.569.047.214一97.282.558.216一125.2108.476.618173.8156.7137.997.220一198.0170.9117.924310.25287.3247.5170.9阀座端口面积（英寸2）适用于压力密封丫形截止阀SEAT PORT AREA F
23、OR PRESSURE SEAL Y-GLOBEVALVES (in 2)阀门通径Valve Size压力等级Pressure Class90015002500839.939.927.21061.961.942.81286.686.660.11486.686.686.616135.4135.486.618135.4135.4135.420198.1198.1135.424302.6302.6198.1螺栓阀帽闸阀全开状态下的流量系数Bolted BonnetGate Valves FULL OPEN CvCv阀门通径压力等级Valve SizePressure Class15030060090
24、0150011/2165165165一1382307307307一27021/2490490490一400371071071065060041300130013001220107052090一一一160063110311031102850250085720572055405025437510893589358495785068401213350133501280011475998014162751627515370139101200016215602156029170一一18287202789026270一一20357603484032140一一24521655105046710一一30862
25、358476575530一一36129500125825114250一一开启度%与流量系数% Open ve % CvLlad。SMd EGA 口 阀门开启度Fl分比0 2C 0 SO 9D IMPer«nt of Full Op电n Cv全升状态下流域系殷百分比图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 Valve
26、s FULL OPEN Cv阀门通径Valve Size压力等级Pressure Class6009001500250021/2350350275190352545041527549258507304606215019251675110083775357529251970105750525045503130128600755065704535141027591507890550016134251195010325721018172001557513425921520209501920016825114502430850276752415016575压力密封缩喉管闸阀全开状态下的流量系数CvPr
27、essure SealVenturi Gate Valves FULL OPEN Cv阀门通径Valve Size压力等级Pressure Class600900150025008 x 6 x 815701385118581510 x 8 x 10279523852155143012 x 10 x 12448540653450251514 x 12 x 14731062855640385516 x 14 x 16900072006270441518 x 16 x 181100097608465616520 x 18 x 20142001218511120796022 x 20 x 221680
28、01600514130964526 x 24 x 262500023000一一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 Class150300600900150011/2636397一一2142168139一11112 /2217275227一一3356392246358315471674049960556461414199213341623152082961234033592508一105720572054404069一127860854470456316
29、一1410416194649840一一16138001380012912一一181342013029一一一20167081627619540一一243338436672一一一305455654652一一一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 Size压力等级Pressure Class150300600900塞形或球形阀瓣Plug orBallV形端口阀瓣V-PortDisc塞形或球形阀瓣Plug orBallV形端口阀瓣V-PortDisc塞形或球形阀瓣Plug orBallV形端口阀瓣V-Por
30、tDisc塞形或球形阀瓣Plug orBallDiscDiscDiscDisc1 1/223一232123一一2434043404340一21/270一70一70一一31009210092100929041851701851701851701705297273一一一一一6440405440405440405一8810745810745780一一10126011501260一一一一121890一1890一1810一一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 Valves FULL OPEN Cv阀门通径Valve Size压力
31、等级Pressure Class9001500250021/2346810121416182024951462686271062172224202955394549006275929580132230536940146521102550339543655465806060941463556271020142017752355302537055465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CvPressure SealVenturi Tilting Disc Check Valves FULL OPEN Cv阀门通径Valve Size压力等级Pressure Class1503006
32、008 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, Lift-Check Valves小于全开状态的估计流量系数CvEstim
33、ating Cv For Less Than Fully Open Valvesild-蚯10('UEfiLolLI&ad 三 阀门开H度门分比P*?*niFull Qoen Cv金开启状志卜的温虹悬ii分比球形止回阀，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阀门通径Valve
34、Size压力等级Pressure Class9001500250021/290654531059565419517010564553952658800695470101250108575012182015801100142205一一压力密封丫球形止回阀，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 Class60090015002500820251750175011751030252725272
35、518751246003825382526501443003650365040751676506000600037751873255825582566252011800912591256225241645013500135009050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 t
36、han 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 Class 900 Pacific pressure seal globe v
37、alve 1/4 open? iffi 和 EO w20h 1b004。 杖）岫PwcMYi of Full Opon Cv个河状态F制旗舐系冠门分比图3丫形球形止回阀，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 Class9
38、00150025008 x 6 x 845039026010 x 8 x 1077069046512 x 10 x 121215105574514 x 12 x 1416 x 14 x 16177521251550一1070一压力密封缩喉管 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 CvPressure 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 811001000100
39、065010 x 8 x 10192516751675112512 x 10 x 12287526002600177514 x 12 x 14437536503650252516 x 14 x 16407534503450387518 x 16 x 18725057005700357520 x 18 x 20695055255525630022 x 20 x 221120086758675592516 x 24 x 261585012825128258600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1820SOLUTION: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 i