safety valven.
/ˈseɪftɪ ˌvalv/, U.S. /ˈseɪfti ˌvælv/ 1.
a. A value which opens automatically to relieve excessive pressure in a boiler, pressure cooker, etc. Also: a similar valve which closes automatically to prevent a drop in pressure.
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society > occupation and work > equipment > machine > machines which impart power > boiler > [noun] > parts of > valves
safety valve1744
clack1829
government valve1837
fusible plug1874
feed check valve1895
1744 J. T. Desaguliers Course Exper. Philos. II. 488 Upon the Safety-Valve there was a Steel-yard, the Place of whose Weight shews the Strength of the Steam.
1815 J. Smith Panorama Sci. & Art II. 134 The safety-valve..is loaded so that the steam escapes when it is stronger than the engine requires.
1862 T. C. Grattan Beaten Paths II. 3 The high-pressure engine of refinement is always furnished with a safety-valve against the danger of explosion.
1930 Boys' Life Jan. 4/2 There's a safety valve that'll let the air blow in but won't let any blow out. That's so if your airhose breaks or gets cut in half, the air that's left in your helmet can't escape.
2010 Daily Mail (Nexis) 3 Mar. Most of the pressure cookers were straightforward to use, with safety valves to stop them exploding.
b. In extended use (chiefly with reference to volcanoes).
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1825 G. P. Scrope Considerations on Volcanos ix. 189 The active volcanos of a system may be reckoned as safety valves,..letting off the excess of calorific communicated from the centre of the globe.
1876 C. D. Warner Winter on Nile i. 22 The volcanic islands which serve as chimneys and safety-valves to this part of the world.
1900 Trans. Royal Soc. N.Z. 32 204 The crater at Cotopaxi is..19,493 ft. above the present level of the Pacific Ocean, showing that once a safety-valve is formed the internal fires keep as much as possible to the one pipe.
1963 R. J. Forbes Stud. Anc. Technol. VII. i. 48 It was generally held that volcanoes and earthquakes were logically related phenomena, the volcanoes acting as safety valves for the forces which generated earthquakes.
2004 J. Dineen Volcanoes (2005) 10 Volcanoes are, in a sense, the safety valves in the earth's crust, releasing the build-up of pressure caused by gases beneath the earth's surface.
2. figurative. A channel or opportunity for the harmless release of pressure caused by stress, excitement, excess energy, etc.; a means of ‘letting off steam’.
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the mind > emotion > excitement > [noun] > opening for giving vent to excitement
safety valve1817
safety vent1963
the mind > emotion > aspects of emotion > manifestation of emotion > [noun] > outward exhibition > outlet for
outlet1625
vent1667
safety valve1817
lightning rod1834
escapement1856
1817 R. Torrens in Pamphleteer 10 524 A well-regulated system of colonization acts as a safety-valve to the political machine.
1825 in W. Hone Every-day Bk. (1826) I. 1344 As a sort of ‘safety valve’,..recourse is had..to the flinging about of..cabbage stalks.
1840 F. Marryat Olla Podrida I. xix. 206 I am convinced that they [sc. public lotteries] were beneficial, acting as safety-valves to the gambling spirit of the nation.
1861 M. Arnold Pop. Educ. France 183 What a safety-valve to the high pressure of a compulsory system is here!
1878 W. Stubbs Constit. Hist. (ed. 2) III. xviii. 276 Commercial activity..was..a safety-valve for energies shut out of their proper sphere.
1945 F. A. Shannon Farmer's Last Frontier ii. 46 There were never enough of these city dwellers transplanted on Western farms to..provide a safety valve for labor discontent.
2002 A. McCrossen Holy Day, Holiday vi. 90 Cycling, like Sunday, was fashioned as a safety valve—an escape from the mundane and worldly.
Compounds
General attributive.
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1848 Jrnl. Franklin Inst. Oct. 271 Began to throw water on the fires, and continued..until the blaze was stopped from between the boilers, then went to safety valve lines.
1852 F. G. Smith & J. Neill Hand-bk. Physiol. (ed. 2) 76 Since this may be advantageous, by preventing the over-filling of the vessels of the lungs, it has been called the safety-valve action of this valve.
1921 Proc. National Electric Light Assoc. 44 ii. 1057/2 The trouble due to safety valve leakage.
1956 ‘J. Wyndham’ Seeds of Time 100 There had been nothing worse than safety-valve grumbling.
1964 R. Miliband in I. L. Horowitz New Sociol. 868 What Mills condemned in Safety-valve welfarism was not the welfare.
2009 J. Bellarby Well Completion Design x. 571 If the safety valve mechanism of a wireline retrievable valve fails, it can simply be replaced.
This entry has been updated (OED Third Edition, September 2011; most recently modified version published online March 2022).
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n.1744