safety valve

Definition

A valve set to open at a pressure below that at which a container holding a gas, vapour, etc. (such as a boiler or pressure cooker), would burst, thus reducing the pressure; a relief valve.

Etymology

From safety + valve.

Example Sentences

• "Spun glass mattresses are used for lagging the boiler, which has three Ross pop safety valves on the front ring."
• "[A]nd to show that there was no shortage of steam, Royal Scot, directly we stopped, blew off vigorously from its safety-valves steam that well might have been used in the cylinders in the interest of timekeeping."
• "[…] I have often thought that it was a great error in our legislature when they consented to put down the public lotteries in England. I am convinced that they were beneficial, acting as safety-valves to the gambling spirit of the nation, and that their prohibition has been productive of much crime and misery."