Twentieth century handbook for steam engineers and electricians, with questions and answers; a practical nontechnical treatise .. (1916)
Swingle, Calvin F. (Calvin Franklin), b. 1846 · 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…
