Selection of manual valves at the inlet and outlet of the safety valve
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Our unit is equipped with two safety valves. When it was installed, there were no manual valves in front of or behind them. Now the safety valves need to be calibrated, but it’s not possible to access them. We want to add two manual valves in front of and behind the safety valves. The pressure rating of these safety valves is 150LB; should the manual valves also have a pressure rating of 150LB?
If the pressure of the safety valve is correct, it’s possible
The nominal pressure of the safety valve is 150LB; does that mean its inlet and outlet flanges are both 150LB? Can I simply use two 150LB valves?
Yeah, they all need to have the same pressure rating. Complementary.
Yes, generally the pressure is higher in front of the safety valve/pressure valve and lower behind it.