> as lemmas
pop safety valve
pop safety valve n.
Brit. 
/pɒp ˈseɪftɪ valv/
, /pɒp ˈseɪftɪ valv/U.S. /ˌpɑp ˈseɪfti ˌvælv/
= pop valve n./ˌpɑp ˈseɪfti ˌvælv/ΘΚΠ
society > occupation and work > equipment > machine > parts of machines > control(s) > [noun] > valve > pop
pop valve1873
pop safety valve1876
1876 Rep. Commissioners U.S. Internat. Exhib. Vienna 1873 I. 413 Ashcroft's patent nickel-seat pop safety valve.
1961 F. A. S. Brown Nigel Gresley xvii. 123 One of the new ‘B12s’..was the subject of extensive rebuilding, and the opportunity was taken to mount..a round-topped fire-box with pop safety valves.
2002 Heating/Piping/Air Conditioning Engin. (Nexis) 74 56 There will be..a pressure increase as the system warms up, probably enough to cause discharge from the pop-safety valve.
<
as lemmas