Micron, a measurement not a rating!

Do you know how well your filtration actually performs?

A common misconception regularly found amongst our customers is when they ask for a filter bag or cartridge with x, y or z micron “rating”…

Actually, microns are the unit of measurement used in linear measurement of distance, it’s actually 1000th of a millimeter and a filter that is marked at “10 microns” is 100th of a millimeter measured gaps between the straining elements of the filter material.

Generally speaking, there is no single accepted method to measure and supply filtration media,
there are however ratings for the efficiency of the material and construction. Therefore, it is impossible to know the quality and ability of the filter media you are buying without knowing at least its efficiency rating.

What does the efficiency rating mean?

The efficiency of a filter determines how well it works, most standard bag filters for example work around 30% efficiency which means they will catch around 1/3rd of the contaminants at the micron size advertised or larger.

While a higher-performing media bag can operate at up to 99.99%, the complication comes as often a lower-rated media can also be a higher-rated one at a different micron size.

So, taking a Rosedale Products standard felt bag as an example, these bags are regarded as a minimum of 50% efficient at their advised micron which means 5 in every 10 particles at the micron size or larger are stopped in the bag. Now take a 1-micron standard bag and multiply the efficiency to 95% (you’ll see why in a minute) it becomes equivalent to a 35-micron 95% efficiency bag… so 9.5 in every 10 particles at 35 microns or larger will be stopped.

Now let’s take the Rosedale Products Graded Density bags by comparison, as standard these bags are 95% efficient and available at 1, 3, 8 & 19-micron offerings (all 95% efficient) now the 1 micron can also be a 99.99% efficient bag but at 99.99% efficiency, it’s a 40-micron particle size. We know confusing right?

This is why Rosedale Filtration Experts are always on hand and willing to discuss your solution thoroughly with you and why you might end up with a filter designation smaller or larger than you were expecting… Frequently customers will come to us with a request of say 10 microns max particle size in the post-filtration flow and actually to best obtain that we may supply a filter with a label showing 1 or 3 microns but the efficiency rating may be 95% at those sizes rather than 10 microns at 99.99% which could remove more than a 10-micron 99.99% filter.

It’s always best to make sure your comparing like for like otherwise you might be putting more of the debris you thought you were filtering out into your product, machine or waste stream and what are the cost implications of this?