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).

LUBRICATION SYSTEM

The lubrication system in the reciprocating compressor is much like that of an automobile engine-a 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.