From Longman Dictionary of Contemporary Englishsafety valveˈsafety valve noun [countable] 1 TEa part of a machine that allows gas, steam etc to escape when the pressure becomes too great2 MPsomething that allows you to get rid of strong feelings without doing any harm Being able to express emotion is a healthy safety valve for the relationship.
Examples from the Corpus
safety valve• Do these eruptions act as a safety valve or will they lead to a cataclysm?• So far the devaluation has acted as a safety valve for the most immediate pressures.• Fortuitously, the advancing Union forces operated as a safety valve.• Humor can be a safety valve in high pressure situations.• Then an interesting phenomenon takes place: they become a safety valve.• It is a safety valve, you might say a brothel of the mind.• Sometimes, a safety valve may be fitted into the boiler flow pipe; a draincock is always fitted in the return.From Longman Business Dictionarysafety valveˈsafety valve noun [countable] a small part on a machine that opens to let out steam or pressure when it becomes too greatthe safety valve device on the boiler 