Air Preparation Basics

Compressed air contains contaminants and moisture which can cause premature wear and tool damage in pneumatic systems. Air preparation equipment (filters, regulators, and lubricators) should be used to maximize the efficiency and service life of these systems. Find out more about air preparation basics and equipment below.


Filters typically come “first” when building air preparation into pneumatic systems. As the name implies, they filter the air for contaminants before it reaches the critical motion components. There are three main types of filters: general-purpose filters for removing moisture and particles, coalescing filters for removing oil aerosols, and activated carbon filters for removing oil vapors.

General-purpose filters are used for most applications, including main headers, branch lines, tools, cylinders, valves, and valve circuits. Oil-removal filters are used where very clean, oil-free air is required, such as fluidic device supplies, air gauging equipment, and air bearings. Activated-carbon filters are utilized when oil vapor in the air is not acceptable, such as with instrumentation or paint spraying.


Pressure regulators are used to reduce pressure to the level required for downstream equipment, limit the force of cylinders, or minimize pressure variation at point of use. They can be individual components positioned downstream from a filter unit, or an integrated filter/regulator unit that combine the features of a filter and a regulator in a single compact body.


Lubricators are utilized downstream of filters and regulators, which pre-condition the air before it arrives at the lubricator. Most pneumatic equipment, even pre-lubricated components, will last longer if oil aerosol is continually added to the compressed air that powers them.

Without lubrication, environmental factors such as extreme temperatures or excessive moisture, and operational factors such as startup and operational friction reduce the service life of most working pneumatic devices. Used oil exiting the compressor is dirty and degraded, therefore it cannot function as a lubricant.

Just a quick note about lubricators:

Some components require clean, dry, non-lubricated air. Other components do require lubrication. Even better, some components are pre-lubed and do not need lubrication. It is best to contact a pneumatic expert to discuss your needs.

Filter/Regulator/Lubricator (FRL) Combination Units

Air preparation components can stand alone in a system or be employed as integrated filter/regulator/lubricators (FRLs). In many applications, a space-saving FRL combination will reduce installation complexity and cost, as well as making maintenance easier.    

Summary of Air Preparation Basics

Using the right equipment for air preparation is important for the integrity of your air supply. If you are unsure of what equipment you require for air preparation, we suggest speaking to an expert.

Need air preparation equipment or need to know more about air preparation basics? Speak to one of our experts today to learn more!