Absolute pressure Pw discharged by the safety valve
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When calculating safety valves, to determine the medium density, there is a formula for calculating the absolute discharge pressure Pw; some say that Pw = P_set + P_atmosphere + overpressure limit, while others claim that the absolute pressure equals the set pressure plus atmospheric pressure
As stated in B.8 of 150, the discharge pressure (absolute pressure) of the relief device consists of two components: the design pressure and the overpressure limit; that is, the discharge pressure equals Pw = P_design + overpressure limit. This is gauge pressure, and since it is an absolute pressure, atmospheric pressure must also be added to it. That is the first formula mentioned by the original poster.
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