1/2 ball valve
3 way valves
3 way solenoid valve
Control valves sizing is according to the requirements of application and must meet both CV and speed criteria.
So when the valve has a CV capacity lower than the maximum possible in the valve size, it is necessary use reduced setting.
The most common reason for reduced setting is that the flow rate is low for the required valve size, particularly when the 1” size valve has been specified as the smallest size to be used. Some end-users stipulate that no control valves should have less than two sizes smaller than the pipe line, it means the valve should not be less than half the size of the size of the line.
The second reason is that in gas or high-pressure steam applications, the control valve is invariably sized at the speed limits of the output port and required CV is much smaller than the total internal diameter CV.
How to Size a Level Control Valve