safety valve
noun [ C ]
ukus PRODUCTION
a part of a machine that opens to release pressure if it becomes too high:
The process involves shutting safety valves beneath the water's surface to prevent oil and gas releases.
something in a system or situation that helps when problems become too great:
Experts say there must be a safety valve built into the system to relieve the stress caused by an economic slowdown.
There's no safety valve, like higher air fare prices, to offset higher oil prices.