Canadian engineer . essure, the movement of thevalve with relation to its seat being measured by a mi-crometer caliper. The results of the tests are plotted in Figs 4 and 5. Asa result of these tests the muffled locomotive pop safetyvalve is now made as shown in Fig. 6. In an addendum to Prof. Millers paper, Mr. A. , of the Crosby Steam Gage & Valve Co., makessome general comments regarding pop safety valves. Quot-ing in part these remarks^ he says: Pop safety valves were invented about 60 years agoand about 30 years later were perfected in this country andwent into general use. Broad
Canadian engineer . essure, the movement of thevalve with relation to its seat being measured by a mi-crometer caliper. The results of the tests are plotted in Figs 4 and 5. Asa result of these tests the muffled locomotive pop safetyvalve is now made as shown in Fig. 6. In an addendum to Prof. Millers paper, Mr. A. , of the Crosby Steam Gage & Valve Co., makessome general comments regarding pop safety valves. Quot-ing in part these remarks^ he says: Pop safety valves were invented about 60 years agoand about 30 years later were perfected in this country andwent into general use. Broadly, the invention consists ofan addition to the disk of the valve so that when the valve is closed the addition is excluded from the action of thesteam. Jlowever, when the valve opens the outflowingsteam acts upon it and with the initial force causes thevalve disk suddenly to rise higher and the spring to becompressed more than it would be with a force due to thesteam pressure acting upon the original area -10 50~w 70 30 SO 100 110 120 130 WO 150 160 170 180 190 200 210Pounds of Steam Distharged per Minute at 2001b Gage Pressure Fig. 4.—Results of Tests on Locomotive Type of PopSafety Valve. The bevel-seated valves (Fig. 3) generally have thisadditional area at the periphery of the disk, outside of theseat, where it forms a chamber with a more or less con-tracted outlet at the extreme lip of the valve, through whichall the steam must pass after escaping over the seat beforeit reaches the open air. As the seat is formed at an angle of 45 deg. to thevertical, the passage between the seat and the disk faces,when the valve opens, is diagonally upward, and what iscalled the lip of the valve is so related to this seat that the
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