Control valve
Thread Content
Why is diameter reduction generally used before and after control valves?
This requires determining the specifications of the control valve based on your operational conditions and process requirements, and making corresponding diameter adjustments during piping; this is generally handled by the automation team
When selecting a control valve, factors such as the pressure difference before and after the valve, flow rate, valve opening degree, and control characteristics need to be taken into account. The valve chosen in this way generally has a smaller equivalent diameter than the pipe, necessitating the use of reducer fittings for connection. The diameter of the pipe decreases at the control valve, which increases the resistance of the fluid at that point; this in turn reduces the pressure of the fluid at the control valve, facilitating regulation and control ； Furthermore, a smaller pipe diameter also helps to reduce the travel distance of the control valve (enabling it to quickly regulate the flow rate once activated), as well as helping to decrease the size of the control valve (mainly referring to the sizes of the drive mechanism and the actuator). Lastly, since control valves are generally expensive, using valves with smaller diameters can significantly reduce costs
The seat diameter of a control valve may be smaller than the pipe diameter; if a control valve with a nominal diameter identical to that of the pipe is used, it will increase the overall cost of the valve. To reduce costs, control valves with a nominal diameter one size smaller are generally chosen.
It is calculated based on the parameters provided by the process, and it has little to do with costs