流量盘算

流量盘算
Flow Calculations

如何应用流量系数
How to use Cv

　　法门流量系数(Cv)是表现阀门通过流体才能的数值。Cv越大，在给定压降下阀门能够通过的流体就越多。Cv值1表现当通过压降为1 PSI时，阀门每分钟流过1加仑15oC的水。Cv值350表现当通过压降为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 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1
FORMULA 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：PSI dp = pressure drop in PSI F = 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2
FORMULA 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：PSI dp = pressure drop in PSI Sg = 比重 Sg = specific gravity Q = 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:

例子
EXAMPLE

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)

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 smallest valve with a pressure drop less than 5 PSIG.

水和蒸汽的备选特征
Selected Properties of Water and Steam 水的(下游)
For Water (Downstream) 所有压力等级
All
Pressures 温度(oF)
Temperature (oF) 100 200 300 400 500 600 0.127 0.129 0.132 0.137 0.143 0.154 蒸汽的(下游)
For Steam (Downstream) 压力
PSIG
Pressure
PSIG 温度(oF)
Temperature (oF) Sat 500 600 700 800 900 1000 1100 100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
1600
1800
2000
2500
3000
4000
5000
6000 1.97
1.46
1.21
1.06
0.950
0.865
0.801
0.747
0.701
0.662
0.628
0.598
0.570
0.545 2.20
1.61
1.30
1.11
0.979
0.895 2.32
1.68
1.38
1.19
1.06
0.960
0.880
0.815
0.759
0.710
0.670
0.629
0.590
0.559 2.44
1.77
1.46
1.26
1.12
1.02
0.941
0.875
0.821
0.773
0.732
0.695
0.662
0.633
0.58
0.54
0.50
0.41
0.31
0.17
0.16
0.16 2.54
1.85
1.52
1.32
1.18
1.08
0.994
0.926
0.870
0.816
0.781
0.745
0.710
0.683
0.63
0.59
0.55
0.48
0.42
0.32
0.24
0.19 2.64
1.95
1.60
1.38
1.23
1.13
1.04
0.972
0.914
0.865
0.823
0.785
0.752
0.723
0.67
0.63
0.59
0.52
0.46
0.38
0.32
0.28 2.74
2.00
1.65
1.43
1.28
1.17
1.08
1.01
0.955
0.917
0.872
0.813
0.789
0.752
0.70
0.66
0.62
0.55
0.49
0.42
0.36
0.32 2.84
2.07
1.71
1.47
1.33
1.22
1.12
1.05
0.99
0.94
0.90
0.86
0.83
0.79
0.74
0.69
0.65
0.58
0.52
0.44
0.39
0.35

阀座端口流速盘算
Calculating Seat Port Velocity

　　下列公式可以用来盘算任何阀门的阀座流速：
　　The following formulas can be used to calculate seat port
velocity in any valve:

流量(磅/小时): 流速: (英尺/秒)= F(

)2 25A Flow (lbs/hr): vel: (fps) = F(

)2 25A 流量(加仑/分钟): 流速: (英尺/秒)= 0.32Q A Flow (GPM): vel: (fps) = 0.32Q A

在此：
Where: F = 流量(磅/小时) F = flow (lbs/hr)

= 比容积的平方根

= square root of specific volume A = 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 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 25A = 90,000 (1.61)2 25 (78.5) = 118.8 英尺/秒 Vel (fps) = F(

)2 25A = 90,000 (1.61)2 25 (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 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 25A = 90,000 (1.61)2 25 (113.1) = 82.5英尺/秒 Vel (fps) = F(

)2 25A = 90,000 (1.61)2 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:

留心
NOTE

　　在断定止回阀通径时，最合适的工作流速应当位于这些范畴内：
　　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240
BB截止止回阀：40 至120
PS晋升式阀瓣止回阀：55至200
PSY形止回阀：148 至200
BB Swing Check Valves - 55 to 115 or 135 to 240
BB Stop Check Valves - 40 to 120
PS Tilt Disc Check Valves - 55 to 200
PS Stop Check Valves - 40 to 180
PS Y- Stop Check Valves - 148 to 200

阀座端口面积“A”(英寸2)
实用于螺栓阀帽阀门
SEAT PORT AREA "A" FOR BOLTED
BONNET VALVES (in2) 阀门通径
Valve Size 压力等级
Pressure Class 150 300 600 900 1500 11/2
2
21/2
3
4
6
8
10
12
14
16
18
20
24
30
36 1.8
3.1
4.9
7.1
12.6
28.3
50.3
78.5
113.1
137.9
182.7
233.7
291.0
424.5
671.9
969.0 1.8
3.1
4.9
7.1
12.6
28.3
50.3
78.5
113.1
137.9
182.7
227.0
283.5
424.5
672.0
942.0 1.8
3.1
–
7.1
12.6
28.3
48.7
74.7
108.4
130.2
170.9
213.8
261.6
380.1
590.9
851.2 1.8
3.1
4.9
6.5
11.8
26.0
44.2
71.0
100.0
117.9
–
–
–
–
–
– 1.5
2.8
4.0
6.0
10.3
22.7
38.5
60.0
84.5
101.6
–
–
–
–
–
–

阀座端口面积(英寸2)
实用于压力密封闸阀，截止阀，晋升式阀瓣止回阀
SEAT PORT AREA FOR PRESSURE SEAL GATE,
GLOBE, TILT DISC CHECK VALVES (in2)

阀门通径
Valve Size 压力等级
Pressure Class 600 900 1500 2500 21/2
3
4
6
8
10
12
14
16
18
20
24 5.4
5.4
9.6
23.2
39.9
61.0
88.7
–
–
173.8
–
310.25 5.9
5.9
10.3
21.7
37.7
58.4
80.5
97.2
125.2
156.7
198.0
287.3 3.3
4.9
8.3
18.9
31.9
48.7
69.0
82.5
108.4
137.9
170.9
247.5 2.4
3.6
5.9
12.6
21.7
34.5
47.2
58.2
76.6
97.2
117.9
170.9

阀座端口面积(英寸2)
实用于压力密封Y形截止阀
SEAT PORT AREA FOR PRESSURE SEAL Y-GLOBE
VALVES (in2)

阀门通径
Valve Size 压力等级
Pressure Class 900 1500 2500 8
10
12
14
16
18
20
24 39.9
61.9
86.6
86.6
135.4
135.4
198.1
302.6 39.9
61.9
86.6
86.6
135.4
135.4
198.1
302.6 27.2
42.8
60.1
86.6
86.6
135.4
135.4
198.1 螺栓阀帽闸阀全开状态下的流量系数Cv
Bolted Bonnet
Gate Valves FULL OPEN Cv 阀门通径
Valve Size 压力等级
Pressure Class 150 300 600 900 1500 11/2
2
21/2
3
4
5
6
8
10
12
14
16
18
20
24
30
36 165
307
490
710
1300
2090
3110
5720
8935
13350
16275
21560
28720
35760
52165
86235
129500 165
307
490
710
1300
–
3110
5720
8935
13350
16275
21560
27890
34840
51050
84765
125825 165
307
490
710
1300
–
3110
5540
8495
12800
15370
29170
26270
32140
46710
75530
114250 –
–
–
650
1220
–
2850
5025
7850
11475
13910
–
–
–
–
–
– 138
270
400
600
1070
1600
2500
4375
6840
9980
12000
–
–
–
–
–
–

图1
螺栓阀帽截止阀
Figure 1
Bolted Bonnet
Globe Valves
(1)当开启度小于
10%时，不建议
用于节流畅用。
(1) not recommended for
throttling at less
than 10% Open.

压力密封闸阀全开状态下的流量系数Cv
Pressure Seal
Gate Valves FULL OPEN Cv

阀门通径
Valve Size 压力等级
Pressure Class 600 900 1500 2500 21/2
3
4
6
8
10
12
14
16
18
20
24 350
525
925
2150
3775
5750
8600
10275
13425
17200
20950
30850 350
450
850
1925
3575
5250
7550
9150
11950
15575
19200
27675 275
415
730
1675
2925
4550
6570
7890
10325
13425
16825
24150 190
275
460
1100
1970
3130
4535
5500
7210
9215
11450
16575

压力密封缩喉管闸阀全开状态下的流量系数Cv
Pressure Seal
Venturi Gate Valves FULL OPEN Cv

阀门通径
Valve Size 压力等级
Pressure Class 600 900 1500 2500 8 x 6 x 8
10 x 8 x 10
12 x 10 x 12
14 x 12 x 14
16 x 14 x 16
18 x 16 x 18
20 x 18 x 20
22 x 20 x 22
26 x 24 x 26 1570
2795
4485
7310
9000
11000
14200
16800
25000 1385
2385
4065
6285
7200
9760
12185
16005
23000 1185
2155
3450
5640
6270
8465
11120
14130
– 815
1430
2515
3855
4415
6165
7960
9645
– 螺栓阀盖旋启式止回阀全开状态下的流量系数Cv
Bolted Cap
Swing Check Valves FULL OPEN Cv 阀门通径
Valve Size 压力等级
Pressure Class 150 300 600 900 1500 11/2
2
21/2
3
4
6
8
10
12
14
16
18
20
24
30 63
142
217
356
716
1414
2961
5720
7860
10416
13800
13420
16708
33384
54556 63
168
275
392
740
1992
2340
5720
8544
19464
13800
13029
16276
36672
54652 97
139
227
246
499
1334
3359
5440
7045
9840
12912
–
19540
–
– –
–
–
358
605
1623
2508
4069
6316
–
–
–
–
–
– –
111
–
315
564
1520
–
–
–
–
–
–
–
–
–

螺栓阀帽截止阀全开状态下的流量系数Cv
Bolted Bonnet
Globe Valves FULL OPEN Cv

阀门
通径
Valve Size 压力等级
Pressure Class 150 300 600 900 塞形
或
球形
阀瓣
Plug or
Ball
Disc V形
端口
阀瓣
V-Port
Disc 塞形
或
球形
阀瓣
Plug or
Ball
Disc V形
端口
阀瓣
V-Port
Disc 塞形
或
球形
阀瓣
Plug or
Ball
Disc V形
端口
阀瓣
V-Port
Disc 塞形
或
球形
阀瓣
Plug or
Ball
Disc 11/2
2
21/2
3
4
5
6
8
10
12 23
43
70
100
185
297
440
810
1260
1890 –
40
–
92
170
273
405
745
1150
– 23
43
70
100
185
–
440
810
1260
1890 21
40
–
92
170
–
405
745
–
– 23
43
70
100
185
–
440
780
–
1810 –
40
–
92
170
–
405
–
–
– –
–
–
90
170
–
–
–
–
–

压力密封晋升式阀瓣止回阀全开状态下的流量系数Cv
Pressure Seal
Tilting Disc Check Valves FULL OPEN Cv

阀门通径
Valve Size 压力等级
Pressure Class 900 1500 2500 21/2
3
4
6
8
10
12
14
16
18
20
24 95
146
268
627
1062
1722
2420
2955
3945
4900
6275
9295 80
132
230
536
940
1465
2110
2550
3395
4365
5465
8060 60
94
146
355
627
1020
1420
1775
2355
3025
3705
5465

压力密封缩喉管晋升式阀瓣止回阀全开状态下的流量系数Cv
Pressure Seal
Venturi Tilting Disc Check Valves FULL OPEN Cv

阀门通径
Valve Size 压力等级
Pressure Class 150 300 600 8 x 6 x 8
10 x 8 x 10
12 x 10 x 12
14 x 12 x 14
16 x 14 x 16
18 x 16 x 18
20 x 18 x 20
22 x 20 x 22 565
955
1550
2175
2660
3550
4410
5650 480
845
1320
1900
2295
3055
3930
4920 320
565
920
1275
1598
2120
2725
3335

球形止回阀，截止止回阀，晋升式止回阀的流量特征曲线
Characteristic Flow Curves for Globe Stop, Stop-Check, Lift-Check Valves

小于全开状态的估计流量系数Cv
Estimating Cv For Less Than Fully Open Valves

图2
球形止回阀，截止止回阀和晋升式止回阀
Figure 2
Globe Stop, Stop-Check and
Lift-Check Valves

压力密封T形球形止回阀，截止止回阀和晋升式止回阀
阀全开状态下的流量系数Cv
Pressure Seal T-Globe Stop,
Stop-Check and Lift-Check Valves FULL OPEN Cv 阀门通径
Valve Size 压力等级
Pressure Class 900 1500 2500 21/2
3
4
6
8
10
12
14 90
105
195
455
800
1250
1820
2205 65
95
170
395
695
1085
1580
– 45
65
105
265
470
750
1100
–

压力密封Y球形止回阀，截止止回阀和晋升式止回阀
阀全开状态下的流量系数Cv
Pressure Seal Y-Globe Stop,
Stop-Check and Lift-Check Valves FULL OPEN Cv

阀门通径
Valve Size 压力等级
Pressure Class 600 900 1500 2500 8
10
12
14
16
18
20
24 2025
3025
4600
4300
7650
7325
11800
16450 1750
2725
3825
3650
6000
5825
9125
13500 1750
2725
3825
3650
6000
5825
9125
13500 1175
1875
2650
4075
3775
6625
6225
9050

　　表中所列流量系数仅实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实用于晋升式阀瓣止回阀和截止阀的流量特征曲线进行估算。不建议将闸阀用在节流畅用中。
　　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，压力等级Class 900的美国太平洋压力密封截止阀在开心胸为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?

图3
Y形球形止回阀，截止止回阀和晋升式止回阀
Figure 3
Y-Globe Stop, Stop-Check and
Lift-Check Valves

压力密封缩喉管球形止回阀，截止止回阀和晋升式止回阀
阀全开状态下的流量系数Cv
Pressure Seal Venturi Globe Stop,
Stop-Check and Lift-Check Valves FULL OPEN Cv 阀门通径
Valve Size 压力等级
Pressure Class 900 1500 2500 8 x 6 x 8
10 x 8 x 10
12 x 10 x 12
14 x 12 x 14
16 x 14 x 16 450
770
1215
1775
2125 390
690
1055
1550
– 260
465
745
1070
–

压力密封缩喉管Y球形止回阀，截止止回阀和晋升式止回阀
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 Class 600 900 1500 2500 8 x 6 x 8
10 x 8 x 10
12 x 10 x 12
14 x 12 x 14
16 x 14 x 16
18 x 16 x 18
20 x 18 x 20
22 x 20 x 22
16 x 24 x 26 1100
1925
2875
4375
4075
7250
6950
11200
15850 1000
1675
2600
3650
3450
5700
5525
8675
12825 1000
1675
2600
3650
3450
5700
5525
8675
12825 650
1125
1775
2525
3875
3575
6300
5925
8600

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%.

　　因此盘算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.

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