Filter Regulator Lubricator. What is the purpose of a Filter Regulator Lubricator ( FRL)? Air leaving a compressor is hot, dirty, and wet—which can damage and shorten the life of downstream equipment, such as valves and cylinders. Before air can be used it needs to be filtered, regulated and lubricated.

An air line filter cleans compressed air. It strains the air and traps solid particles (dust, dirt, rust) and separates liquids (water, oil) entrained in the compressed air. …Pressure regulators reduce and control fluid pressure in compressed air systems.

The lubricator function of an FRL unit ensures that the air is dosed with a small amount of lubrication oil to help pneumatic components work effectively. Lubricators ensure that the correct amount of oil is being used to reduce the friction between moving components.