Fisher Type H120 direct-operated relief valve has a preset and pinned spring retainer.
The inlet pressure registers directly on a spring-opposed poppet assembly, which includes a Nitrile (NBR) disk. When the inlet pressure increases above the spring setting, the poppet and disk assembly is pushed away from the metal seat. Type H120 may be used where venting to the atmosphere is acceptable and where some pressure-relieving tolerance is acceptable.
