II. MEDIUM-PRESSURE COMPRESSORS.
A. High-duty Apparatis.-
B. Nigh-duty Machines. Engine for Bessmer Converters. -
Fig. 144 represents an engine of this class, employed in
Pittsburg. The cylinders are disposed vertically, the air-cylinder
being uppermost and inverted. Around this cylinder is a water-jacket,
and the valves are placed in the ends, which, divided by a diametrical
partition, constitute inlet and delivery chambers. The valves
are formed of very light disks of vulcanized India-rubber, supported
by disks of brass. They move on bronze seats inserted in the
cylinder-ends, and are held thereon by spheral springs. The dimensions,
etc., are as follows: Absolute air-pressure, 2.66 atmospheres;
volume of air furnished at this pressure, 2,389 cubic feet. Motor:
Diameter of piston, 41 inches; stroke, 47 inches. Air-cylinder:,
Diameter of piston, 53.4 inches; stroke, 47 inches; useful volume
of cylinder, 63.7 cubic feet ; revolutions per minute, 50; theoretic
volume of air delivered minute 6,356 cubic feet.