How high can my system pressure be before my valve opens?

A minimum operating gap of 10% between the system operating pressure and the safety valve’s nameplate set pressure should be maintained. Since direct spring-operated safety valves may “simmer” or “warn” at 90% of the nameplate set pressure, and since the factory standard leak test is performed at 80% of nameplate set pressure, better seat tightness performance can be expected with an operating gap of 20%.