Metal filter assembly by Fluid Conditioning Products

What is Filter Efficiency, and Why Does It Matter in Metal Filters?

In our most recent blog post, we discussed the latest research that proves all-metal filters outperform fiberglass in aviation applications based on demanding real-life testing. One of the key ways that all-metal wire mesh and sintered metal filters surpass legacy materials like fiberglass is by providing excellent filter efficiency for a longer period of time in service.

But, what exactly is filter efficiency (aka filtration efficiency),and why does it matter?

Today’s post focuses on how filter efficiency is measured and references some test cases that have shown all-metal filters performing with greater than 99% filtration efficiency.

How Filtration Efficiency is Measured

The textbook definition of filtration efficiency (from Hutten’s Handbook of Nonwoven Filter Media) is the rating of a given filter medium by the percentage of contaminants removed by that filter medium. The following equation expresses this:

Filtration Efficiency Formula

Hutten notes that the quantity of contaminant can be assessed “by weight or mass, by number of particles, by volume, and interestingly enough by cross-section area of the particles.” Regardless, in real-life testing of various filter media—such as in the aviation industry testing we discussed in that earlier blog post we mentioned above—contamination downstream from filtering should be less than 95%.

Some legacy materials, like glass fiber, can achieve this level of contaminant reduction, up to about 97-98%. However, metal filter media can often achieve efficiencies of nearly 100%—a fantastic difference that translates to real money saved on replacement parts in crucial systems on military aircraft, submarines, and other extremely valuable vehicle applications! (See this white paper from Bekaert for more.)

Filtration Efficiency Should Not Decrease Over Time

With the use of legacy filtration materials like fiberglass/glass fiber and cellulose, filtration efficiency unfortunately gets worse as time passes, which leads to more contamination in critical fluids or air. Glass fiber media, for instance, both degrades and sheds particulates even from its initial installation. And both factors negatively affect filter efficiency.

All-Metal Filters Can Ensure Consistent Efficiency

On the other hand, all-metal filter elements neither degrade nor shed particles.

How? The main reason is that all-metal filters are binderless, fixed by metal-to-metal contact points that do not deteriorate. This means no breakdown of filter performance over time. All-metal filters begin with excellent efficiency ratings, and those stay consistent until the metal filter medium is changed out at the end of its life.

Testing of sintered metal filters in nuclear applications reported by the U.S. Department of Energy Office of Scientific and Technical Information going back to the early 1980s show just how efficient these media are.

Want the Most Efficient Filter Options for Your Application?

Talk to our filtration experts at Fluid Conditioning Products first. When you’re looking to increase filtration efficiency—and keep that number up over time—all-metal filters are the proven way to go.

Fluid Conditioning Products is proud to be known for our corrosion-resistant wire mesh filters made from stainless steel, nickel-copper, brass, and bronze. Get in touch with us today to learn more about our filter manufacturing and supply capabilities and experience the FCP difference.