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Standard vs. Coalescing Air Filters for Spray Booth Systems



Anyone familiar with spray foam tools knows the importance of using the proper air filters for your SPF equipment.

Spray foam filters are designed to remove airborne contaminants including pipe scale, rust, pipe dope, and other harmful particulates from your system before they damage your equipment or compromise your work. There are two main types of SPF filters, standard filters and coalescing filters, and their use could not be more diverse.

With your standard spray foam air filter, air flows into the inlet port through a deflector plate which creates the centrifugal action necessary to remove any contaminants. Filter shrouds assure the proper swirling action occurs and that air does not pass through the filter before large particles and liquids are removed.

The baffle separates the lower portion of the bowl where the removed liquids and particles collect and do not re-enter the airflow system. These particles and fluids are drained from the system while clean air passes through the supply line.Coalescing spray foam air filters remove suspended liquids including oil and water in the same way standard filters work, but are used for removing aerosolized fluids not removed from a standard filter. The most common filter assembly for this type of system consists of a 3-unit combination of a Filter, Regulator, and Lubricator (FRL).

The clean airflow passes through the coalescing filter into the regulator which sets the appropriate air pressure. Then, the air passes through the lubricator to provide a light oil for lubricating O-rings and seals throughout the air system. It is important to place the filter first in order to keep the diaphragm on the regulator clean to ensure constant control and a longer life.

Its best to hook a large standard filter directly to the compressor tank to remove any rust and water prior to entering the FRL. If your SPF system uses a refrigerated dryer, put the lubricator section after the refrigerated dryer to avoid plugging the system with oil and make sure to add a coalescing filter to this section, as well.Using the correct filters for your SPF system will ensure that your parts last longer and your work is never damaged due to equipment malfunctions.

Many SPF parts are delicate and require airflow free from particulates in order to function properly. But, with a combination of proper filter use and diligent cleaning of all equipment, SPF tools can last years without replacement.

Above is a picture describing how to properly plumb a line to prevent rust, water and other contaminants from entering the supply line with the use of a Drip Leg. The drip leg drops below your other supply line to allow fluid and particles to accumulate in the lower section so you can blow it out when you open the ball valve.

Bring your supply lines off to the side, or over the top if running horizontally. That prevents the water from free flowing directly to your supply lines. Always have a ball valve to close the air supply so you can work on each leg without having to kill the complete system. Shown here is our filter/coalesce/regulator assembly. The lubricator is further down line. We use an inline lubricator at each transfer pump.

Screw this directly to the pump and screw the supply line onto this. As air passes through, the oil is atomized to an aerosol and goes into the air section of your pumps. This provides clean/dry air from your filters, and then lubricates the seals in the pump. Eliminating the water and adding a small amount of oil will triple the life of your air motors. This is also a must have for your drum mixer.

Water makes rust and the rust eats the air motor seals. The lubricator only hold 1/2oz and we use the TSL fluid. If you have to fill it 1 time a month you're doing fine. Filling it every day provides too much oil; this can gum up the system.