The coolers are used to dissipate heat generated during compression. There are two types of heat exchangers used on air compressors, air-cooled and water-cooled.
Air-Cooled Heat Exchanger. Air-cooled heat exchangers are most often used on small compressors. The air-cooled heat exchanger is a finned, tubular radiator.
Water-Cooled Heat Exchanger. The most common design of water-cooled heat exchangers, shell and tube type, consists of a single bundle of tubes enclosed inside a cylindrical shell. The air to be cooled passes through the tubes while the water passes over the tubes. Baffles are often provided in the tube bundle to direct the water flow across the heat exchanger tubes in the most efficient manner.
The intercooler is located between the discharge of one cylinder and the intake of the next cylinder of multistage compressors. The intercooler reduces the temperature and the volume of the compressed air for delivery to the next compression stage.
The aftercooler is located at the discharge of the last cylinder to cool the air, reduce its volume, and to liquify any condensable vapours.
Preventive maintenance inspection:
Daily Inspection. Inspect the cooler daily for the following conditions:
Proper operation of the automatic controls and instruments
Water leaks, temperature, and flow rate
Any deviations from normal temperature or pressure drops across the cooler
Operational preventive maintenance:
Observe the following procedures during normal operation.
Maintain rated cooling waterflow. Avoid excessive waterflow which might cause erosion.
Adjust waterflow rates slowly to avoid sudden temperature changes in the cooler.
Shut down compressor if condensate trap is collecting excessive amounts of water. Cooler tubes may be leaking.
Shut down compressor if cooler air temperature is abnormally high. Leak in cooler tubes could be allowing air to displace cooling water in waterside of cooler.