Lubricators are part of the pneumatic FRL system (filter-regulator-lubricator) which help to keep pneumatic tools or other end use devices lubricated when they are supplied with compressed air. The internal mechanisms of valves, motors and drive cylinders will all dry up and become damaged if insufficient lubrication is supplied.
Lubricators work by injecting an aerosol micro fog of oil into the air stream after it is released from the regulator. Compressed air enters a lubrication chamber through an inlet port and then travels over the opening of a needle valve. This valve is attached to a pick-up tube which is submerged in a machine oil reservoir, pulling up the oil by the venturi effect. The oil is then emitted at the outlet port as a fine aerosol mist. The lubricant preserves and prolongs the lifespan of downstream machinery and enhances its performance. The emitted amount of lubrication can be adjustable, and the needle valve is usually situated inside a clear nylon or polycarbonate sight glass, so as to make the oil flow rate adjustment easier.
The lubricator must always be the final element of the FRL unit. If it is connected in any other conformation, with the air input, for example, going straight to the lubricator, this will interfere with the regulator operation, which will have to deal with oil-laden air. If it is connected before the filter, the lubricating oil will be separated out of the air stream by the filter and drained off, leaving very little or none going out to the connected equipment.