Selection issues for control valves
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Regarding the calculation of the pressure difference before and after the control valve, there are several questions: 1. For the \"pressure drop\" in the pressure drop distribution ratio S, what is the state of the valve at that time? Full open or typical? 2. Does system pressure drop refer to the pressure drop across the entire pipeline system starting from the gas source, or it refers to the pressure drop in the pipeline from the control valve to the equipment that uses the gas? 3. Does the system pressure drop take into account the opening status of other manual valves in the pipeline? 4. Are the pressures before and after the valve both absolute pressures? 5. What is the minimum possible differential pressure across the control valve?
1. In the pressure drop distribution ratio S, the “pressure drop” corresponds to a valve in its fully open state. 2. System pressure drop refers to the pressure loss in the pipeline from the control valve to the equipment that uses gas. 3. The opening status of other manual valves in the pipeline should be taken into account in the system pressure drop calculation. 4. The pressures before and after the valve refer to absolute pressure. 5. The minimum differential pressure across a control valve depends on the specific model and specifications of the valve, and it is necessary to determine this based on the actual selection data. Generally speaking, the smaller the minimum differential pressure across the control valve, the better its control performance; however, this is also influenced by other factors such as the pressure and temperature of the working medium. .
Regarding the calculation of the pressure difference before and after the control valve, there are several questions: 1. For the \"pressure drop\" in the pressure drop distribution ratio S, what is the state of the valve at that time? Full open or typical? A: It refers to the state when the valve is fully open. 2. What does system pressure drop refer to – the pressure drop across the entire pipeline system starting from the air source, or the pressure drop in the pipeline from the control valve to the equipment that uses the air? A: It is the pressure drop across the entire piping system. 3. Does the system pressure drop take into account the opening status of other manual valves in the pipes? A: Not considered; only full open is taken into account. 4. Are the pressures before and after the valve both absolute pressures? A: Whether it’s absolute pressure or gauge pressure, just make sure not to get them mixed up. Sometimes when a negative value is entered, the software cannot perform calculations, so switch to using absolute pressure. 5. What is the minimum possible differential pressure across the control valve? A: Maximum pressure before the valve – minimum pressure after the valve; sometimes the maximum design pressure is used. Please pay attention to spelling errors and words
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