The flow rate of common medium through a valve

Valve flow and flow rate mainly depend on the valve size, structure, pressure, temperature and medium concentration, resistance and other factors. The flow and flow rate is interdependent, under the condition of a constant flow value when the flow rate increase, the valve port area is small and the resistance of the medium is large, leading to the valve is easy to damage. A large flow rate will produce static electricity to flammable and explosive media; However, a low flow rate means low production efficiency. It is recommended to choose a low flow rate (0.1-2 m/s) according to the concentration for large and explosive media such as oil.

The purpose of the flow rate controlling in the valve r is mainly to prevent the generation of static electricity, which depends on the critical temperature and pressure, the density, physical properties of the medium. In general, knowing the flow and flow rate of the valve, you can calculate the nominal size of the valve. Valve size is the same structure, fluid resistance is not the same. Under the same conditions, the greater the resistance coefficient of the valve, the more the flow rate through the valve and the lower the flow rate; The smaller the drag coefficient, the less the flow rate flow through the valve. Here is the flow rate of some common medium through the valve for your reference.

Medium Type Conditions Flow velocity, m/s
Steam Saturated vapor DN > 200 30~40
DN=200~100 25~35
DN < 100 15~30
Superheated steam DN > 200 40~60
DN=200~100 30~50
DN < 100 20~40
Low-pressure steam P<1.0(Absolute pressure) 15~20
Medium pressure steam P=1.0~4.0 20~40
High-pressure steam P=4.0~12.0 40~60
Gas Compressed gas(Gage pressure) Vacuum 5~10
P≤0.3 8~12
Ρ=0.3~0.6 10~20
Ρ=0.6~1.0 10~15
Ρ=1.0~2.0 8~12
Ρ=2.0~3.0 3~6
Ρ=3.0~30.0 0.5~3
Oxygen(Gage pressure) Ρ=0~0.05 5~10
Ρ=0.05~0.6 7~8
Ρ=0.6~1.0 4~6
Ρ=1.0~2.0 4~5
Ρ=2.0~3.0 3~4
Coal gas   2.5~15
Mond gas(Gage pressure) Ρ=0.1~0.15 10~15
Natural gas   30
Nitrogen gas(Absolute pressure) Vacuum/Ρ=5~10 15~25
Ammonia gas(Gage pressure) Ρ<0.3 8~15
Ρ<0.6 10~20
Ρ≤2 3~8
Other medium Acetylene Gas P<0.01 3~4
P<0.15 4~8
P<2.5 5
Chloride Gas 10~25
Liquid 1.6
 Chlorine hydride Gas 20
Liquid 1.5
liquid ammonia (Gage pressure) Vacuum 0.05~0.3
Ρ≤0.6 0.3~0.8
Ρ≤2.0 0.8~1.5
Sodium hydroxide (Concentration) 0~30% 2
30%~50% 1.5
50%~73% 1.2
Sulfuric acid 88%~100% 1.2
hydrochloric acid / 1.5


Low viscosity water (Gage pressure) Ρ=0.1~0.3 0.5~2
Ρ≤1.0 0.5~3
Ρ≤8.0 2~3
Ρ≤20~30 2~3.5
Heating network circulating water 0.3~1
Condensate water Self-flow 0.2~0.5
Seawater, slightly alkaline water Ρ<0.6 1.5~2.5


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