Safety Valve Steam

safety valve
A valve opening automatically to relieve excessive pressure, esp. in a boiler
A means of giving harmless vent to feelings of tension or stress
The safety valve is a provision in the Sentencing Reform Act and the United States Federal Sentencing Guidelines that authorizes a sentence below the statutory minimum for certain nonviolent, non-managerial drug offenders with little or no criminal history.
A safety valve is a valve mechanism for the automatic release of a substance from a boiler, pressure vessel, or other system when the pressure or temperature exceeds preset limits. It is part of a bigger set named pressure safety valves (PSV) or pressure relief valves (PRV).
a valve in a container in which pressure can build up (as a steam boiler); it opens automatically when the pressure reaches a dangerous level

steam
steamer: travel by means of steam power; "The ship steamed off into the Pacific"
water at boiling temperature diffused in the atmosphere
The invisible gaseous form of water, formed by boiling, from which this vapor condenses
The expansive force of this vapor used as a source of power for machines
The vapor into which water is converted when heated, forming a white mist of minute water droplets in the air
emit steam; "The rain forest was literally steaming"