Pressure tapping inside and outside the self-acting control valve
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When should a self-acting control valve be pressurized internally? When to take external pressure readings? I earnestly ask for your advice!
Does it refer to pressure measurement before the valve and pressure measurement after the valve?
It is determined by the valve’s structure; refer to the product manual.
Do self-acting control valves also have internal and external pressure taps? I only know about taking pressure readings before and after the valve. As required, if the pressure behind the valve is to be controlled, a pressure measurement is taken behind the valve; if the pressure in front of the valve is to be controlled, a pressure measurement is taken in front of the valve
Pressure tapping inside the valve refers to the use of pressure taps that are already provided on the valve body, while pressure tapping outside the valve involves creating openings in the pipeline for taking pressure readings. Pressure tapping inside/outside the valve is not the same as pressure tapping before/after the valve. Even for self-acting valves with internal pressure tapping, there are distinctions between tapping before and after the valve.
Self-acting pressure control valves can be used for pressure and temperature regulation. Regarding the location of the pressure measurement point, it should be more than 2D away from the valve； The pressure tap behind the valve should be greater than 6D. Pressure gauges should also be installed before and after the valve, and these gauges should be placed close to the pressure sampling points so that the set values match the actual pressure readings. As for what LZ mentioned regarding ‘when is it necessary to take pressure samples from a self-acting control valve?’ When to take external pressure readings? ’This depends on the specific operating conditions.