II. MEDIUM-PRESSURE COMPRESSORS.
A. Low-duty Apparatis.-
2. Compressors for supplying Air under Pressure in Wells
-Fig. 142 is a double-acting compressor used in sinking wells
near Liege, Belgium. It Is driven by a vertical engine, as shown.
The aspiration-valves are fixed on the upper half of each bead
of the air-cylinder and open directly into the atmosphere. The
compressing valves open into a chamber communicating with the
lower section of each cylinderhead. This chamber is connected
by a tube with the well. The following are the dimensions, etc.:
Absolute air-pressure, 3 atmospheres; volume of air furnished
at this pressure, 12 cubic feet. Motor: Diameter of piston,
14.9 inches; stroke 27.5 inches ; normal steam-pressure, 52.5
lbs. Air-cylinder: Diameter of piston, 23.6 inches; stroke, same;
useful volume of cylinder, 6 cubic feet; revolutions per minute,
80; theoretic volume generated per minute, 35.5 cubic feet.