Micron Rating. What are they and why is it important?

The Filter Guys

What is a Micron?

A micron is a measurement of size. It is one millionth of a metre (1/1000000m) or a thousandth of a millimetre (1/1000mm). In filtration, a micron rating is a rating of the media’s capacity to stop dirt (it is not an efficiency rating). The micron rating will be nominal or absolute.

A nominal micron rating means that a media may be explained as 10 micron but that is a mean average, it probably varies between 5 and 15 micron over the surface of the media itself; this often applies to cellulose media which is a natural product. Engine oil and fuel filters are often nominally rated.

An absolute micron rating means that the media has a uniformed surface and will ‘do what it says on the tin.’ A 10 micron absolute filter will not allow particles of 10.1 micron or bigger through at all. Absolute filters are man made products, such as glass fibre, and are manufactured to an extremely high specification. Hydraulic filters are often absolute rated (but not necessarily for all hydraulic applications).

Why is it important?

In filtration the micron rating of the element is very important to guarantee its correct operation. The wrong type of media can mean more dirt gets through the filter than you want and this can cause wear and tear and even complete breakdowns of your engines and hydraulic equipment.

Take a lubrication system on your engine. Oil is pumped between the moving parts of the engine, this oil contains particles, if the oil isn’t filtered before being sent into the engine then wear and tear will occur. The space between moving parts may only be 30 or 40 microns. If oil contains particles of that size then dirt is going to jam and consequently build up between moving parts. Over many hours (or years) of operation with inadequate filtration this build up of dirt will cause the moving parts to jam which will cause catastrophic failure of an engine leading to expensive downtime and repair costs.

Of course, over time filters will clog with dirt too but they are easily sourced from Sterling Filtration Ltd and replaced. They hold the damaging particles so the engine doesn’t have to. A filter may cost ten, twenty, fifty, one hundred pounds and sometimes even more, but compared to the cost of downtime of a machine and the stripping and rebuilding of an engine they are easily the most cost effective way of keeping your engines and machinery running properly all of the time. See your operators manual for service intervals.