Pneumatics 101

MICRON

A measurement equal to 0.000039 inches.

In reference to filtration, the average size of the openings between pieces of the filter media are represented in microns. For example, a 40-micron filter has larger openings than a 5-micron filter. Consequently, the 40-micron filter element will let larger particles pass through the filter than the 5-micron element.

As a general rule, the smaller micron rating for a filter is better, but as with most everything, there is a trade-off. Flow capability usually drops off as the micron rating gets smaller. To overcome this, low micron-rating filters must have larger elements to keep from sacrificing precious flow.

Another factor to consider is the fact that a filter with smaller openings, such as a coalescing type, will clog quicker than a general purpose filter. Replacing filter elements can become expensive if it is happening too often. A good solution to this problem is to use a pre-filter. Always install a general purpose filter (in the 40- to 50-micron range) upstream of a coalescing filter (5-micron range or less). The general purpose filter will capture the majority of the particles before they reach the coalescing filter, thus saving the coalescing filter element from clogging too soon. Even though this requires two filters and seems expensive initially, this could mean huge savings on coalescing filter elements in the long term.

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