Fig. 367.
The machine is made with duplex cylinders for the low pressures used in sand blast work and the like, and with either duplex or compound cylinders for higher pressures. In the compound type, an intercooler is supplied, through which the air passes from the low pressure to the high pressure cylinder.
The air cylinders are water-jacketed and provided with hooded heads, so that air may be supplied to them from outside the compressor-room; the cylinders are cast in one piece with the frame.
Fig. 368.
The air-valves, both inlet and outlet, are of the poppet type, fitted with light springs, and work vertically. On account of their position at the bottom of the cylinder, they are well lubricated, and, acting vertically, they have little tendency to wear out of line with their seats.
The air intake passage is tapped to receive a supply pipe leading from out-of-doors, or from some place where cool and clean air is obtainable. The compressed air is discharged into a passage which is tapped for a pipe to convey it to the air-receiver.
All parts of the compressor are easily accessible for inspection, adjustment, or repair. The air-heads may be removed without disturbing any of the pipe connections. The valves may be taken out by unscrewing the bonnets.
Table
of parts of the Imperial Compressor.