AS9120B, ISO 9001:2015, AND FAA AC 0056B ACCREDITED

How To Choose the Right Coalescing Filter?

Compressed air systems are popular instruments that can handle a wide variety of packaging, pumping, and material handling tasks. As air can heat up and become humid or dirty as a result of external conditions, air filtering and preparation is often an essential element to keep compressed air systems working at their best. For this reason, coalescing filters are often used in conjunction with compressed air systems as a way of cleaning and filtering the air before it enters the system. In this article, we will be discussing the various options of coalescing filters as well as how to select the best one for your application.

How Does a Coalescing Filter Work?

A coalescing filter works by removing oil or other particulates by forcing air through a screen or filtering element. When the air changes direction and collides with itself at high speeds, it forces any contaminants to coalesce, or stick together. This creates drops which are caught on an outer sock and gain mass, being forced down into an attached bowl. The oil, water, or other particles can then be drained away so as to avoid draining back into the system and contaminating it.

How To Select a Coalescing Filter

There are a few major features to consider when choosing the right coalescing filter for your assembly. Firstly, there are several possible materials which the bowl can be made from. Polycarbonate bowls are transparent and very durable but cannot be exposed to certain substances such as harsh chemicals and ammonia. Alternatively, metal bowls provide less visibility but can be exposed to lower temperatures and higher pressures than polycarbonate bowls. Another feature to consider is whether to choose an automatic or manual drain option. Whereas automatic drains can carry out the draining process without intervention, manual drains require consistent checking and maintenance.

Coalescing filters will also have different air purity classes which determine what degree of particle removal they can muster. Some applications may require cleaner air than others so it is important to consider what level of air purity is needed. For added ease, coalescing filters can also be fitted with indicators which turn from green to red when the filter elements need replacing. This mechanism is not strictly required but it may be useful for eliminating the time it takes to manually check the filters. Finally, it is important to consider the size and weight of the coalescing filter so that it will fit well into the surrounding assembly. It should be noted that in general, polycarbonate bowls are much lighter than metal bowls, making them especially useful for lightweight applications.


Compressed air systems function at their best when they are supplied with pure air, free from moisture and contaminants. If you are an airplane owner or operator looking for top-grade components for your vessel, you can depend on Automatize Aviation for quality parts that are suited to your specific requirements. As a leading supplier of aircraft tools and maintenance equipment, we are well equipped to handle all your fulfillment needs, even providing expedited shipping to handle strict deadlines and AOG situations. Begin the purchasing process with us today to see all that Automatize Aviation can do as your strategic sourcing partner!


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