relief valve
noun
a device that, when actuated by static pressure above a predetermined level, opens in proportion to the excess above this level and reduces the pressure to it.Compare safety valve(def 1).
Dictionary.com Unabridged
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Related Words for relief valve
outletExamples from the Web for relief valve
Historical Examples of relief valve
As the pressure lowers, the excess gas can escape through a relief-valve.
Creatures of the AbyssMurray Leinster