III. HIGH-PRESSURE COMPRESSORS.
B. High-duty Apparatus.-
3. Compressors refrigerated by Layer of Water on the Piston. -This mode of cooling is much more periphery of the cylinder which is in contact with the heated air is kept wet, as a quantity of water passes around the piston which may be sufficient to saturate the air with watery vapor during its compression. In this state, air may be compressed to 7.5 atmospheres without its temperature exceeding 194° Fahr.
The portable compressor of MM. Saultier and Lemonnier, a section
of which is given in Fig. 150, belongs to this class. It is a
small, strong machine, built of sufficiently light weight to be
carried by a mule. The cylinders, of which there are two, are
open above. A thin stream of water passes to a circular channel
in the upper part of the cylinders, by which it is distributed
around their inner portion to the pistons, through the inlet-valves,
in which it enters into the space in which the air is compressed,
so that it comes in direct contact with the air. There are three
valves in each cylinder: two inlets in the piston, and one delivery
at the cylinder-bottom. They are simply bronze cups on seats
of the same metal, provided with suitable springs, and guided
by stems, dimensions, data, etc. Absolute air. pressure, 5 atmospheres;
volume of air furnished at this pressure by both cylinders, 5
cubic feet 269 cubic inches. Motor of 10-horse power, any form.
Compressor: Diameter of pistons, 9.3 inches; stroke, 11.7 inches;
useful volume of cylinders, 479 cubic feet; revolutions per minute,
27 ; theoretic volume delivered by the pistons at this velocity,
26 cubic feet.