Particulate filter efficiency

Particulate filter efficiency

These filters are generally sold at 99.5% efficiency/ Beta 200 at a defined micron rating with some older lower cost versions sold at 98.6% (beta 75).

Using this example a 4 micron filter at 99.5% efficiency means that 199/200 particles >4 microns would be stopped by that filter. Unfortunately, these efficiencies are calculated under ideal laboratory conditions using constant flow, temperature, pressures etc. which do not represent real-life conditions.

High quality suppliers offer higher efficiencies including 99.9% (Beta 1000), 99.995% (Beta 2000), and 99.975% (Beta 4000).?Higher suggests better but not always.??Many games are played by the manufacturers to have a marketing advantage over the competition.

What is confusing also is that the same filters would have different efficiencies at different micron ratings.

A good example is the main lube oil filters on known large frame gas turbines. The micron rating of this filter is 5 microns at 98.6% but is approximately 40 microns at beta 1000.?Most users struggle with particle count and to fix the problem would logically think that moving to a 3 micron would be the solution but it is not.?The 3 micron also at 98.6% would be approximately 35 microns at beta 1000, so not any improvement.?In this case you need to go to a higher micron filter! But one with very high efficiency. i.e. 6 microns beta 1000-4000.??If you operate any of these turbines, I recommend checking what you are using as there would be significant opportunities to fix issues on this topic with a very simple and cost effective fix.

The goal should always be to the mechanical system requirements and not about the micron rating of the filters.?Journal bearings require <14microns at 99.975 efficiency, while roller bearings require <6 microns at 99.975 efficiency. While lower is better, these are the maximum allowable limits.

SVR systems SVR? Oil Varnish Removal System | EPT Clean Oil use filters at 0.9 micron that are beta 1000 and would be approximately 3 microns at beta 4000.?These are rated to ISO standards under dynamic test conditions so would be much more reflective of real-world conditions.

We only use and recommend synthetic fiber filters as the properties are consistent at all moisture levels.?Cellulose filters swell in the presence of water which significantly reduces the efficiency.??