向量平行公式：阀门流量计算方法介绍

2020年11月19日发(作者：曾秉正)




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。C v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15
o
C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15
o
C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 60
o
F water with a pressure drop (dp) of 1 PSI across the valve. A Cv of 350 means a
valve will pass 350 gpm of 60
o
F water with a dp of 1 PSI.
公式1
FORMULA 1
流速：磅小时(蒸汽或水)
FLOW RATE LBSHR (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 .

=
比容积的平方根，单位：立方英尺磅
(阀门下游)
3

= square root of a specific volume in ftlb.
(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:
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 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
EXAMPLE
1. 通过DN350, 压力等级Class 900的压力密封闸阀，水温400
o
F，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
o
F water,
1500 PSIG, and 5,000,000 lbshr flow rate?
解：采用公式1
Solution: Use formula 1.
F = 5,000,000
o

=
0.137 (从水温为400F的表中得到)
o

= 0.137 (from chart for water at 400F)
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 14
with the same conditions as example 1.
解：采用公式1
Solution: Use formula 1.
Cv = 6285 (来自本页)
Cv = 6285 (from page 26)

3. 温度900
o
F, 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
900
o
F, 1200 PSI steam service at a flow rate of 500,000 lbshr?
解：采用公式1
Solution: Use formula 1.
F = 500,000
o

=
0.785 (来自900F, 1200 PSIG蒸汽表)
o

= 0.785 (from chart for steam at 900F, 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
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)
温度(
o
F)
所有压力等级
All
Pressures
100
0.127
200
0.129

蒸汽的(下游)
Temperature (
o
F)
300
0.132
400
0.137
500
0.143
600
0.154
For Steam (Downstream)
压力
PSIG
Pressure
PSIG
100
200
300
400
Sat
1.97
1.46
1.21
1.06
500
2.20
1.61
1.30
1.11
600
2.32
1.68
1.38
1.19
700
2.44
1.77
1.46
1.26
800
2.54
1.85
1.52
1.32
900
2.64
1.95
1.60
1.38
1000
2.74
2.00
1.65
1.43
1100
2.84
2.07
1.71
1.47
温度(
o
F)
Temperature (
o
F)
500
600
700
800
900
1000
1100
1200
1300
1400
1600
1800
2000
2500
3000
4000
5000
6000
0.950
0.865
0.801
0.747
0.701
0.662
0.628
0.598
0.570
0.545
0.979
0.895
1.06
0.960
0.880
0.815
0.759
0.710
0.670
0.629
0.590
0.559
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
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
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
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
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 port
velocity in any valve:
F(
流量(磅小时): 流速: (英尺秒)=
)
2

25A
F(
Flow (lbshr): vel: (fps) =
)
2

25A
0.32Q
流量(加仑分钟): 流速: (英尺秒)=
A
0.32Q
Flow (GPM): vel: (fps) =
A

在此：
Where:
F =
流量(磅小时)
F = flow (lbshr)

=
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 (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
o
F，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
90,000 lbshr of steam at 500
o
F and 200 PSIG?
解：
从蒸汽表得
Answer:
From the steam tables is 1.61, and from the seat port area table A is 78.5 in
2
.
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
。
F(
流速: (英尺秒)=
)
2

=
90,000 (1.61)
2

= 118.8 英尺秒
25 (78.5) 25A
F(
Vel (fps) =
)
2

=
90,000 (1.61)
2

= 118.8 fps
25 (78.5) 25A
例：
DN300型号180 (压力等级150)旋启式止回阀，流体介质为温度500
o
F，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
90,000 lbshr of steam at 500
o
F and 200 PSIG?
解：
查表得
Answer:
From the tables is 1.61 and A is 113.1 in
3
.
为1.61，A为 113.1英寸
3
.
F(
流速: (英尺秒)=
)
2

=
90,000 (1.61)
2

= 82.5英尺秒
25 (113.1) 25A
F(
Vel (fps) =
)
2

=
90,000 (1.61)
2

= 82.5 fps
25 (113.1) 25A
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, 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, the optimum operating velocities should fall within these
ranges:
BB旋启式止回阀：55
BB截止止回阀：40
至115
至120

或135至240
PS提升式阀瓣止回阀：55
PSY形止回阀：148
至200

to 115
to 120
至200
BB Swing Check Valves - 55
BB Stop Check Valves - 40
PS Tilt Disc Check Valves - 55
PS Stop Check Valves - 40
PS Y- Stop Check Valves - 148
or 135




to 240
to 200
to 180
to 200
阀座端口面积“A”(英寸
2
)
适用于螺栓阀帽阀门
SEAT PORT AREA
BONNET VALVES (in
2
)
压力等级
阀门通径
Valve Size
150
1
1

2

2
2
1

2

3
4
6
8
10
12
14
16
18
1.8
3.1
4.9
7.1
12.6
28.3
50.3
78.5
113.1
137.9
182.7
233.7
300
1.8
3.1
4.9
7.1
12.6
28.3
50.3
78.5
113.1
137.9
182.7
227.0
600
1.8
3.1
–
7.1
12.6
28.3
48.7
74.7
108.4
130.2
170.9
213.8
900
1.8
3.1
4.9
6.5
11.8
26.0
44.2
71.0
100.0
117.9
–
–
1500
1.5
2.8
4.0
6.0
10.3
22.7
38.5
60.0
84.5
101.6
–
–
Pressure Class
20
24
30
36
291.0
424.5
671.9
969.0
283.5
424.5
672.0
942.0

261.6
380.1
590.9
851.2
–
–
–
–
–
–
–
–
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 (in
2
)
压力等级
阀门通径
Valve Size
600
2
1

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

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-GLOBE
VALVES (in
2
)
压力等级
阀门通径
Valve Size
900 1500 2500
Pressure Class
900
5.9
5.9
10.3
21.7
37.7
58.4
80.5
97.2
125.2
156.7
198.0
287.3
1500
3.3
4.9
8.3
18.9
31.9
48.7
69.0
82.5
108.4
137.9
170.9
247.5
2500
2.4
3.6
5.9
12.6
21.7
34.5
47.2
58.2
76.6
97.2
117.9
170.9
Pressure Class
8
10
12
14
16
18
20
24
39.9
61.9
86.6
86.6
135.4
135.4
198.1
302.6
螺栓阀帽闸阀全开状态下的流量系数Cv
Bolted Bonnet
Gate Valves FULL OPEN Cv
压力等级
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
阀门通径
Valve Size
150
1
1

2

2
2
1

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
300
165
307
490
710
1300
–
3110
5720
8935
13350
16275
21560
27890
34840
51050
84765
125825

Pressure Class
600
165
307
490
710
1300
–
3110
5540
8495
12800
15370
29170
26270
32140
46710
75530
114250
900
–
–
–
650
1220
–
2850
5025
7850
11475
13910
–
–
–
–
–
–
1500
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
用于节流应用。
(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
压力等级
阀门通径
Valve Size
600
2
1

2

3
4
6
8
10
12
14
16
18
20
24
350
525
925
2150
3775
5750
8600
10275
13425
17200
20950
30850

900
350
450
850
1925
3575
5250
7550
9150
11950
15575
19200
27675
1500
275
415
730
1675
2925
4550
6570
7890
10325
13425
16825
24150
2500
190
275
460
1100
1970
3130
4535
5500
7210
9215
11450
16575
Pressure Class
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
压力等级
阀门通径
Valve Size
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
26 x 24 x 26
1570
2795
4485
7310
9000
11000
14200
16800
25000
900
1385
2385
4065
6285
7200
9760
12185
16005
23000
1500
1185
2155
3450
5640
6270
8465
11120
14130
–
2500
815
1430
2515
3855
4415
6165
7960
9645
–
Pressure Class
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
压力等级
阀门通径
Valve Size
150
1
1

2

2
2
1

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
300
63
168
275
392
740
1992
2340
5720
8544
19464
13800
13029
16276
36672
54652
600
97
139
227
246
499
1334
3359
5440
7045
9840
12912
–
19540
–
–
900
–
–
–
358
605
1623
2508
4069
6316
–
–
–
–
–
–
1500
–
111
–
315
564
1520
–
–
–
–
–
–
–
–
–
Pressure Class

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
压力等级
Pressure Class
150
阀门
通径
Valve Size
塞形
或
球形
阀瓣
Plug or
Ball
Disc
1
1

2

2
2
1

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
–
V形
端口
阀瓣
V-Port
Disc
塞形
或
球形
阀瓣
Plug or
Ball
Disc
23
43
70
100
185
–
440
810
1260
1890

21
40
–
92
170
–
405
745
–
–
V形
端口
阀瓣
V-Port
Disc
300
塞形
或
球形
阀瓣
Plug or
Ball
Disc
23
43
70
100
185
–
440
780
–
1810
–
40
–
92
170
–
405
–
–
–
V形
端口
阀瓣
V-Port
Disc
600 900
塞形
或
球形
阀瓣
Plug or
Ball
Disc
–
–
–
90
170
–
–
–
–
–
压力密封提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
压力等级
阀门通径
Valve Size
900
2
1

2
95
1500
80
2500
60
Pressure Class
3
4
6
8
10
12
14
16
18
20
24
146
268
627
1062
1722
2420
2955
3945
4900
6275
9295

132
230
536
940
1465
2110
2550
3395
4365
5465
8060
94
146
355
627
1020
1420
1775
2355
3025
3705
5465
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 Seal
Venturi Tilting Disc Check Valves FULL OPEN Cv
压力等级
阀门通径
Valve Size
150
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

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
565
955
1550
2175
2660
3550
4410
5650
300
480
845
1320
1900
2295
3055
3930
4920
600
320
565
920
1275
1598
2120
2725
3335
Pressure Class
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，截止止回阀和提升式止回阀
Figure 2
Globe Stop, Stop-Check and
Lift-Check Valves
压力密封T形球形止回阀，截止止回阀和提升式止回阀
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
压力等级
阀门通径
Valve Size
900
2
1

2

3
4
6
8
10
12
14
90
105
195
455
800
1250
1820
2205

1500
65
95
170
395
695
1085
1580
–
2500
45
65
105
265
470
750
1100
–
Pressure Class
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Cv
Pressure Seal Y-Globe Stop,
Stop-Check and Lift-Check Valves FULL OPEN Cv
压力等级
阀门通径
Valve Size
600
8
10
12
14
16
18
20
24
2025
3025
4600
4300
7650
7325
11800
16450
900
1750
2725
3825
3650
6000
5825
9125
13500
1500
1750
2725
3825
3650
6000
5825
9125
13500
2500
1175
1875
2650
4075
3775
6625
6225
9050
Pressure Class
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 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14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 14 open?

图3
Y形球形止回阀，截止止回阀和提升式止回阀
Figure 3
Y-Globe Stop, Stop-Check and
Lift-Check Valves
压力密封缩喉管球形止回阀，截止止回阀和提升式止回阀
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
压力等级
阀门通径
Valve Size
900
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

1500
390
690
1055
1550
–
2500
260
465
745
1070
–
Pressure Class
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
压力等级
阀门通径
Valve Size
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
1100
1925
2875
4375
4075
7250
6950
900
1000
1675
2600
3650
3450
5700
5525
1500
1000
1675
2600
3650
3450
5700
5525
2500
650
1125
1775
2525
3875
3575
6300
Pressure Class
22 x 20 x 22
16 x 24 x 26
11200
15850
8675
12825
8675
12825
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14时阀门的比率是52%.
Consulting Figure 2, the percent of fully open Cv at 14 valve open is 52%.
因此计算14全开的流量系数Cv为：
0.52 x 1820 = 946.
The Cv at 14 open is then computed as:
0.52 x 1820 = 946.