Get clean compressed air by using the right compressed air filters. Protect your pneumatic equipment.

Compressed air filters protect your equipment from dust, dirt, oil and water. Dust will wear down your equipment (like the air motor in grinders, pneumatic actuators and it can make pneumatic control valves get stuck.Especially when the dirt and dust is combined with oil (which is often the case with compressors), a sticky mess can form inside valves, motors and other compressed air equipment.

To protect your equipment, you need to install some compressed air filters.

Which ones? Find out below…

There are many different kinds of filters, and I have often seen people using the wrong one.

I have seen many ‘compressed air filter mistakes’ for that matter, like: wrong filters installed, too small filters installed, filters installed in the wrong place.

People also tend to forget about their filters… while the compressor gets its service every year, people seem to think that their filters will last a lifetime!

That’s not true of course… and it will cost you money!

Filter buildup

Look at the picture above for what a typical filter looks like. The workings are quite simple: air enters on one side and goes through the filter element, where all dust, water or oil is collected. The clean air then leaves the filter housing on the other side.

Filter types

So you need a compressed air filter, but are overwhelmed by all the different types, sizes and specifications. Don’t worry! Let me help you..There are:

Particulate filters - Stage 1

Particulate compressed air filters are used to remove dust and particles from the air. These filters come first and are placed before Coalescing filters to prevent blockages or premature failure of secondary filters.

Coalescing filters - Stage 2

Coalescing filters are used to capture oil and/or moisture that is suspended in the compressed air in very tiny droplets.

These contaminates are usually compressor lube oils, residual cutting oils and pipe dope from the pipe joints, condensed moisture, carbonised oils and solutions of dissimilar oils.

Coalescing filters should always flow from the inside of the filter element to the outside of the filter element. This allows for the oil and water droplets to collect on the fibres of the filter element and meet at crossover points and become larger and larger droplets (the process of coalescing) as they travel downward and outward to the base of the filter element. The large droplets drop off the base of the filter element into the sump area of the filter housing and ultimately into an automatic float drain where the liquids are drained out of the system.

A coalescing filter may remove liquid contaminants by three methods:

Direct Impact – typically 1 micron and larger size particles

Interception – typically between 0.1 and 0.6 micron

Diffusion – typically 0.1 micron and smaller size particles

Activated carbon filters - Stage 3

Activated carbon filters will remove odors and vapors. They are used in factories where food is produced or for breathing-air for example.

Filter elements

As you can see above, the compressed air filter usually is made up of two main parts: the housing and the filter element.

The filter element itself is the part that is doing the job: filtering your compressed air.

In some cases, the filter housing is doing an important job too: it’s often used to separate dust or water/oil droplets by cyclone action. What does it mean? The housing is designed in such a way that the compressed air moves around in it like in a tornado. All the solid particles and droplets will get smashed into the walls of the housing, while the rest of the air moves to the filter element.

You can buy the filter elements separately from the housing, so you can change them for new ones every year or so.

Be carefull when buying your filter housings: what kind of filter elements can they hold? If you like to change filter type later on, do you need a new housing also?

Also, check the maximum flow rate. If you’re thinking about buying extra compressors or a bigger one in the near future, it might be a good idea to over-size your air filters so you don’t have to buy new ones in the future.

Costs and considerations

When shopping for compressed air filters, keep in mind that quality is important.

Quality air filters will produce cleaner air, which means fewer problems with your equipment.

Quality air filters have a lower pressure-drop then low-quality ones. This will save you energy. Every pressure drop in your system (from filters, dryers, long piping etc.) will require you to put your compressor on a higher setpoint, which will cost you extra electricity.

Over time, dust will accumulate in your filters. All this dust will cause an extra obstacle for the compressed air. This means the pressure drop over your filter will become higher over time.

Low-quality air filters will clog up quicker than quality air filters. This means that you’ll have to buy new filters more often. But it also means that the pressure drop over your filter will become higher, quicker, with low-cost air filters.