Pressure before and after the control valve
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I would like to ask whether the pressure of the fluid passing through a control valve always decreases? Does that mean the pressure behind the valve is always higher than that in front of the valve?
The pressure in front of the valve is higher than that behind it; otherwise, backflow will occur
By the way, by how much is the pressure behind the valve usually lower than the pressure in front of the valve? Can it be estimated roughly when filling out the form?
By the way, by how much is the pressure behind the valve usually lower than the pressure in front of the valve? Can it be estimated roughly when filling out the form?
Fill out a form? It’s usually included in the design specifications provided by design firms, or you can turn to the manufacturers of control valves; calculating it on our own would be quite troublesome
“\"By how much is the pressure behind the valve generally lower than the pressure in front of the valve?\" No one can give you an answer to that. This needs to be calculated based on specific process conditions, and the calculation is quite complex; it is usually left to the manufacturers of control valves to carry out.
It is possible for the pressure before and after the valve to be equal (isobaric condition), or it can be higher before the valve than after it (with a pressure difference). As for how large this pressure difference is, that is, the magnitude of the pressure difference, it needs to be calculated based on the specific process
Pressure is lost when fluid passes through a valve
Several people are just talking nonsense based on guesswork. Don’t speak recklessly when you don’t understand something, lest you mislead others. A control valve is a type of adjustable throttling element; since it is a throttling element, it inevitably involves pressure loss. It is generally considered to be in the range of 0.05~0.1 MPa. However, this is not absolute; specifically, the process design must determine the pressure difference before and after the valve, so as to calculate the diameter of the control valve and the appropriate CV value. The pressure difference downstream of the valve is determined based on process requirements, rather than being estimated. For example, after using a temperature and pressure reducer, if there is a loss of 0.1 MPa, can the equipment following it handle that? It depends on the process requirements. But generally speaking, as long as the process requirements are met, the lower the pressure loss, the better. Do you know anything about saving energy and reducing consumption?