Figure 8-17.-Example of an aftercooler on a reciprocating
type of air compressor.
the compressed air to the atmosphere reducing the
temperature to a point where most of the moisture is
removed. This eliminates the difficulties that moisture
causes throughout the system and at the point where the
air is used. Aftercoolers are normally found only on
reciprocating units and are placed between the discharge
valve and the air receiver (fig. 8-17).
The lubrication system in the reciprocating
compressor is much like that of an automobile enginea
pressurized system force feeding oil to lubrication
points (fig. 8-18). Oil assists the piston rings in forming
a tight seal in the cylinders and performs a certain
amount of cooling. Typical small compressors use a
splash type of lubrication system.
As we have seen, vane and screw type of air
compressors depend on oil for more than just
lubrication. The oil lubricates the rotor bearings and
internal working parts and adds to the efficiency of the
compressor by forming a tight seal between each air
compartment of the vanes or screws. Circulating oil also
acts as a cooling medium absorbing the heat generated
Figure 8-18.-Pressure type of lubricating system on a reciprocating type of air compressor.