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Comparison table of relationship between valve diameter and medium flow rate
As we all know, the flow rate and flow rate of the valve mainly depend on the diameter of the valve, and it is also related to the resistance of the valve structure to the medium. At the same time, it has a certain internal relationship with the pressure, temperature, medium concentration and other factors of the valve. The flow area of the valve is directly related to the flow rate and flow rate, which are two interdependent quantities. When the flow rate is constant, the flow rate is large, the flow channel area can be smaller; when the flow rate is small, the flow channel area can be larger. On the contrary, the flow rate is small when the flow area is large, and the flow rate is large when the flow area is small.
1. The flow rate of medium is large, the valve diameter can be smaller, but the resistance loss is large, and the valve is easy to be damaged. High flow rate will produce electrostatic effect on flammable and explosive media, causing danger; low flow rate, low efficiency, uneconomic. For high viscosity and explosive media, the flow rate should be smaller. The flow rate of oil and high viscosity liquid depends on the viscosity, generally 0.1 ~ 2m / s.
2. In general, the flow rate is known and the flow rate can be determined by experience. The nominal diameter of the valve can be calculated by flow rate and flow rate.
3. Valve diameter is the same, its structure is different, fluid resistance is not the same. Under the same conditions, the greater the resistance coefficient of the valve, the more the flow rate and flow rate of fluid through the valve decrease; the smaller the resistance coefficient of the valve, the less the flow rate and flow rate of fluid through the valve decrease.
The common flow rates of various media are shown in the table below:
| 流体名称 | 使用条件 | 流速（m/s） |
| 饱和蒸汽 | DN＞200 DN=200～100 DN＜100 | 30～40 25～35 15～30 |
| 过热蒸汽 | DN＞200 DN=200～100 DN＜100 | 40～60 30～50 20～40 |
| 低压蒸汽 | ρ＜1.0（绝压） | 15～20 |
| 中压蒸汽 | Ρ=1.0～4.0（绝压） | 20～40 |
| 高压蒸汽 | Ρ=4.0～12.0（绝压） | 40～60 |
| 压缩气体 | 真空 Ρ≤0.3（表压） Ρ=0.3～0.6（表压） Ρ=0.6～1.0（表压） Ρ=1.0～2.0（表压） Ρ=2.0～3.0（表压） Ρ=3.0～30.0（表压） | 5～10 8～12 10～20 10～15 8～12 3～6 0.5～3 |
| 氧气 | Ρ=0～0.05（表压） Ρ=0.05～0.6（表压） Ρ=0.6～1.0（表压） Ρ=1.0～2.0（表压） Ρ=2.0～3.0（表压） | 5～10 7～8 4～6 4～5 3～4 |
| 煤气 | 2.5～15 | |
| 半水煤气 | Ρ=0.1～0.15（表压） | 10～15 |
| 天然气 | 30 | |
| 氮气 | Ρ=5～10（绝压） | 15～25 |
| 氨气 | 真空 Ρ＜0.3（表压） Ρ＜0.6（表压） Ρ≤2（表压） | 15～25 8～15 10～20 3～8 |
| 乙炔水 | 30 5～6 | |
| 乙炔气 | ρ＜0.01（表压） ρ＜0.15（表压） ρ＜2.5（表压） | 3～4 4～8 5 |
| 氯 | 气体 液体 | 10～25 1.6 |
| 氯化氢 | 气体 液体 | 20 1.5 |
| 液氨 | 真空 Ρ≤0.6（表压） Ρ≤2.0（表压） | 0.05～0.3 0.3～0.8 0.8～1.5 |
| 氢氧化钠 | 浓度0～30% 浓度30%～505 浓度50%～73% | 2 1.5 1.2 |
| 硫酸 | 浓度88%～93% 浓度93%～100% | 1.2 1.2 |
| 盐酸 | 1.5 | |
水及粘度相似液体 | Ρ=0.1～0.3（表压） Ρ≤1.0（表压） Ρ≤8.0表压） Ρ≤20～30（表压） 热网循环水、冷却水 | 0.5～2 0.5～3 2～3 2～3.5 0.3～1 |
| 水及粘度相似液体 | 压力回水 | 0.5～2 |
| 水及粘度相似液体 | 无压回水 | 0.5～1.2 |
| 自来水 | 主管Ρ=0.3（表压） 支管Ρ=0.3（表压） | 1.5～3.5 1～1.5 |
| 锅炉给水 | ＞3 | |
| 蒸汽冷凝水 | 0.5～1.5 | |
| 冷凝水 | 自流 | 0.2～0.5 |
| 过热水 | 2 | |
| 海水、微碱水 | Ρ＜0.6（表压） | 1.5～2.5 |
As we all know, the flow rate and flow rate of the valve mainly depend on the diameter of the valve, and it is also related to the resistance of the valve structure to the medium. At the same time, it has a certain internal relationship with the pressure, temperature, medium concentration and other factors of the valve. The flow area of the valve is directly related to the flow rate and flow rate, which are two interdependent quantities. When the flow rate is constant, the flow rate is large, the flow channel area can be smaller; when the flow rate is small, the flow channel area can be larger. On the contrary, the flow rate is small when the flow area is large, and the flow rate is large when the flow area is small.
1. The flow rate of medium is large, the valve diameter can be smaller, but the resistance loss is large, and the valve is easy to be damaged. High flow rate will produce electrostatic effect on flammable and explosive media, causing danger; low flow rate, low efficiency, uneconomic. For high viscosity and explosive media, the flow rate should be smaller. The flow rate of oil and high viscosity liquid depends on the viscosity, generally 0.1 ~ 2m / s.
2. In general, the flow rate is known and the flow rate can be determined by experience. The nominal diameter of the valve can be calculated by flow rate and flow rate.
3. Valve diameter is the same, its structure is different, fluid resistance is not the same. Under the same conditions, the greater the resistance coefficient of the valve, the more the flow rate and flow rate of fluid through the valve decrease; the smaller the resistance coefficient of the valve, the less the flow rate and flow rate of fluid through the valve decrease.
The common flow rates of various media are shown in the table below:
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