阀门流量计算方法
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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.
例子 EXAMPLE 1. 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/小时的压降 是多少？ What is the pressure drop through a 14" Class 900 pressure seal gate valve with 400oF water, 1500 PSIG, and 5,000,000
600 0.154
蒸汽的
(下游)
For Steam (Downstream)
压力
温度(oF)
PSIG
Temperature (oF)
Pressure PSIG Sat 500 600 700 800 900 1000 1100
100 1.97 2.20 2.32 2.44 2.54 2.64 2.74 2.84
0.50 0.55 0.59 0.62 0.65
0.41 0.48 0.52 0.55 0.58
0.31 0.42 0.46 0.49 0.52
0.17 0.32 0.38 0.42 0.44
0.16 0.24 0.32 0.36 0.39
0.16 0.19 0.28 0.32 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:
200 1.46 1.61 1.68 1.77 1.85 1.95 2.00 2.07
300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1600 1800 2000 2500 3000 4000 5000 6000
1.21 1.30 1.38 1.46 1.52 1.60 1.65 1.71
= 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:
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.
F(
)2
流速: (英尺/秒)=
=
25A
90,000 (1.61)2 25 (78.5)
3. 温度900oF, 压力1200 PSI，流速500,000磅/小源自文库的蒸汽应用 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 900oF, 1200 PSI steam service at a flow rate of 500,000 lbs/hr? 解：采用公式1 Solution: Use formula 1.
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
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.
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"x12"x14" Class 900 Venturi pressure seal gate valve 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)
1.06 1.11 1.19 1.26 1.32 1.38 1.43 1.47
0.950 0.979 1.06 1.12 1.18 1.23 1.28 1.33
0.865 0.895 0.960 1.02 1.08 1.13 1.17 1.22
0.801
0.880 0.941 0.994 1.04 1.08 1.12
lbs/hr flow rate? 解：采用公式1 Solution: 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)
= 118.8 英尺/秒
F(
)2
Vel (fps) =
=
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
0.747
0.815 0.875 0.926 0.972 1.01 1.05
0.701
0.759 0.821 0.870 0.914 0.955 0.99
0.662
0.710 0.773 0.816 0.865 0.917 0.94
0.628
0.670 0.732 0.781 0.823 0.872 0.90
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.
= 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)
水和蒸汽的备选特性 Selected Properties of Water and Steam
所有压力等级 All
Pressures
水的
(下游)
For Water (Downstream) 温度(oF)
Temperature (oF) 100 200 300 400 500 0.127 0.129 0.132 0.137 0.143
为1.61，A为 113.1英寸3. Answer: From the tables
is 1.61 and A is 113.1 in3. F(
)2
流速: (英尺/秒)=
=
25A
90,000 (1.61)2 25 (113.1)
= 82.5英 尺/秒
F(
)2
Vel (fps) =
=
25A
90,000 (1.61)2 25 (113.1)
0.598
0.629 0.695 0.745 0.785 0.813 0.86
0.570
0.590 0.662 0.710 0.752 0.789 0.83
0.545
0.559 0.633 0.683 0.723 0.752 0.79
0.58 0.63 0.67 0.70 0.74
0.54 0.59 0.63 0.66 0.69
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。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 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.
F(
)2 流量(磅/小时): 流速: (英尺/秒)=
25A
F(
)2 Flow (lbs/hr): vel: (fps) =
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 (lbs/hr)
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.
例子 EXAMPLE 1. 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/小时的压降 是多少？ What is the pressure drop through a 14" Class 900 pressure seal gate valve with 400oF water, 1500 PSIG, and 5,000,000
600 0.154
蒸汽的
(下游)
For Steam (Downstream)
压力
温度(oF)
PSIG
Temperature (oF)
Pressure PSIG Sat 500 600 700 800 900 1000 1100
100 1.97 2.20 2.32 2.44 2.54 2.64 2.74 2.84
0.50 0.55 0.59 0.62 0.65
0.41 0.48 0.52 0.55 0.58
0.31 0.42 0.46 0.49 0.52
0.17 0.32 0.38 0.42 0.44
0.16 0.24 0.32 0.36 0.39
0.16 0.19 0.28 0.32 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:
200 1.46 1.61 1.68 1.77 1.85 1.95 2.00 2.07
300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1600 1800 2000 2500 3000 4000 5000 6000
1.21 1.30 1.38 1.46 1.52 1.60 1.65 1.71
= 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:
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.
F(
)2
流速: (英尺/秒)=
=
25A
90,000 (1.61)2 25 (78.5)
3. 温度900oF, 压力1200 PSI，流速500,000磅/小源自文库的蒸汽应用 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 900oF, 1200 PSI steam service at a flow rate of 500,000 lbs/hr? 解：采用公式1 Solution: Use formula 1.
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
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.
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"x12"x14" Class 900 Venturi pressure seal gate valve 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)
1.06 1.11 1.19 1.26 1.32 1.38 1.43 1.47
0.950 0.979 1.06 1.12 1.18 1.23 1.28 1.33
0.865 0.895 0.960 1.02 1.08 1.13 1.17 1.22
0.801
0.880 0.941 0.994 1.04 1.08 1.12
lbs/hr flow rate? 解：采用公式1 Solution: 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)
= 118.8 英尺/秒
F(
)2
Vel (fps) =
=
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
0.747
0.815 0.875 0.926 0.972 1.01 1.05
0.701
0.759 0.821 0.870 0.914 0.955 0.99
0.662
0.710 0.773 0.816 0.865 0.917 0.94
0.628
0.670 0.732 0.781 0.823 0.872 0.90
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.
= 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)
水和蒸汽的备选特性 Selected Properties of Water and Steam
所有压力等级 All
Pressures
水的
(下游)
For Water (Downstream) 温度(oF)
Temperature (oF) 100 200 300 400 500 0.127 0.129 0.132 0.137 0.143
为1.61，A为 113.1英寸3. Answer: From the tables
is 1.61 and A is 113.1 in3. F(
)2
流速: (英尺/秒)=
=
25A
90,000 (1.61)2 25 (113.1)
= 82.5英 尺/秒
F(
)2
Vel (fps) =
=
25A
90,000 (1.61)2 25 (113.1)
0.598
0.629 0.695 0.745 0.785 0.813 0.86
0.570
0.590 0.662 0.710 0.752 0.789 0.83
0.545
0.559 0.633 0.683 0.723 0.752 0.79
0.58 0.63 0.67 0.70 0.74
0.54 0.59 0.63 0.66 0.69
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。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 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.
F(
)2 流量(磅/小时): 流速: (英尺/秒)=
25A
F(
)2 Flow (lbs/hr): vel: (fps) =
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 (lbs/hr)