Filter, regulator, lubricators are often a critical part of a compressed air system. They are actually 3 separate modules that often get bolted together for simplicity.
Filters – as described elsewhere filters are essential in any compressed air system to keep the air quality high by removing particles, water droplets and oil from the compressed air. Typically a filter includes a robust housing and a internal filter element. The element should be replaced annually or when it gets blocked
Regulator – a regulator reduces the downstream air pressure of the system. A regulator needs to be fitted with a downstream pressure gauge so the required pressure can be set. The regulator pressure is usually set by rotating a large knob until the desired downstream system pressure is reached. Usually the regulator can be locked in a certain position fixing the downstream pressure.
Lubricators – A lubricator is a device that allows a small amount of oil/lubricant to be released into the compressed air stream. This oil then lubricates downstream hand tools that are attached to the air supply, prolonging the life and efficiency of the hand tools. The lubricator needs to be topped up with oil regularly.