Twentieth century handbook for steam engineers and electricians, with questions and answers; a practical nontechnical treatise on the care and management of steam engines, boilers and electric machinery (1922)
Swingle, Calvin Franklin, 1846- [from old catalog] · Chicago, F. J. Drake & company · leaf 148
modern pop valve is generally re-liable^ but^ like everything else^ if it is allowed to standidle too long it is likely to become rusty and stick. There-fore it should be allowed to blow off at least once or twicea week in order to keep it in good condition. Most pop valves for stationary boilers… … The ratio of safety valve area to that of grate surface is^for the old style lever and weight valve^, 1 sq. in. of valvearea for each 2 sq. ft. of grate, surface^ and for pop valves1 sq. in. of valve area for each 3 sq. ft. of grate surface. Each boiler in a battery should have its own safety…
