SAFM / SAFD / SAFL / SAM / SAMD / SAMG / SAMH Series Coalescing Filters

Particulate filters are very effective in removing condensate and particulates from compressed air lines.  However, for specialized applications that require as dry air as possible, a coalescing filter is highly recommended. 

We are still working on making all of our coalescing filter varieties available, but basic principles and filtration properties will apply for all variations that we offer.

What is the difference between particulate and coalescing filters?

Particulate filters remove particulates and moisture by forcing air through a single filtration medium.  Typically this medium, commonly referred as filter element, will be porous, allowing air to pass through and catching moisture and debris.  The filtration efficiency is measured by the size of the openings present in the filter medium, measured in micrometers (commonly referred to as micron, or μm symbol).

Coalescing filters will either have an element or cartridge that consists of multiple layers, sometimes of varying material types and micron sizes.  Having air pass through a coalescing element will cause particulates and moisture to collect to a much finer degree, as filtration is achieved through the multiple layers.  Coalescing filters will have much lower micron ratings, but will exhibit lower flow rates, as air will face much more restriction than through a particulate filter.

When is it recommended to install a coalescing filter?

There are many applications that may require filtration by a coalescing filter.  A few of the more popular applications include spray painting, sandblasting (soda blasting), and plasma cutting. 

These applications require compressed air that is free of moisture and oil that gets produced by compressors.  Coalescing Filters that are rated at 1 micron or smaller (i.e. 0.3 micron, 0.01 micron) will help to remove any oil mist or condensate that carries over from compressors.

Do I need to install a prefilter before a coalescing filter? Why?

Yes, it is highly recommended to install a prefilter (typically a particulate filter) upstream before the coalescing filter.  The prefilter will allow removal of a majority of moisture particles and larger contaminants before air passes through the coalescing filter.  This ensures the flow rate of the coalescing filter and lengthens the life of the coalescing element/cartridge.

Where should the coalescing filter be installed in the compressed air system?

The coalescing filter will work best when installed as close to the point of use as possible. 

Compressed air is very hot when generated by compressors.  The air cools and condenses moisture that is present in the compressed air.  If filter(s) are installed directly after the compressor, air that has not sufficiently cooled may pass through the filter(s), and moisture may condense downstream. 

To prevent this from occurring, we recommend lengthening the distance of piping between the compressor and the filter(s), generally at least 25 ft or longer.  Lengthening the piping distance will allow air to condense sufficiently before entering filtration.

Can the element or cartridge be cleaned?

Unlike particulate elements, the coalescing elements/cartridges cannot be cleaned.  They can only be replaced as needed.

When should elements/cartridges be replaced?

Replacing elements/cartridges timespans will vary depending on the frequency of use.  But we generally recommend replacing them every 6 months or if there is a pressure drop greater than 7psi.

What micron ratings are available for coalescing filters?

Our coalescing filters are categorized by the following micron ratings:

SAFL Series – 1 micron
SAFM Series – 0.3 micron
SAM Series – 0.1 micron
SAMD & SAFD Series – 0.01 micron

**SAMG Series – Classified as ‘Water Separator’, the cartridge is rated to 1 micron but specialized specifically for water removal

**SAMH Series – Specialized cartridge combining filtration properties of SAM & SAMD series, rated to 0.01 micron