Getting what you want from your air filters (1)

Tuesday - 12 June 2018

Long service life

Whether it’s food, batteries or an expensive piece of machinery, most purchases we make, we hope will last for a long time. Obviously, the period of time that we consider a ‘long time’ varies from product to product. But a purchase that lasts longer than its rivals is normally preferable. And the same is true for air filters.

A longer-lasting air filter gives greater return on the original investment and delays the need to repurchase. It reduces the number of filters you need to hold in stock, the labor spent on installation and your disposal costs too. And filters that last longer are also better for the environment; reducing waste and the number of freight trucks on the road.

But what determines that a filter has come to the end of its service life? And what factors make a filter last longer than its rivals?

End of life

Two things spell the end for an air filter – damage and dust.

A filter can be exposed to some rough treatment throughout its life, often before it has even been installed. Air handling units are often sited in places that are awkward to reach, so filters face a lengthy – and sometimes bumpy – journey to their point of installation. And once in place in an air handling unit, variations to the air flow and incoming particulate can also damage the filter media or frame. If damage does occur, the dust-laden air can pass through the filter to the downstream application, people or equipment that you are trying to protect.

Dust may not cause such catastrophic or instant failure, but it too will eventually bring about the end of a filter’s service life. As the filter separates contaminant from the incoming air flow, the dust collects on the filter media. This dust cake blocks the air flow, causing the pressure drop – and so energy consumption – to rise rapidly. In fact, a brand-new filter will account for around 25% of the energy consumption of an air handling unit. A loaded filter increases this value to 50%. So, while it’s tempting to delay the replacement of clogged filters for as long as possible, changing too late could well cost more in the long run.

A design for life

As filter manufacturers, we focus on maximizing the life of our filters to provide the best possible value for our customers. We do this by choosing the strongest materials and combining them in the most robust construction possible. And we also lengthen service life by finding new ways to increase the dust holding capacity of our filters.

For example, we have developed special depth-loading media. Here, the media design allows the dust to penetrate deeper into the fibers instead of settling on the surface. This slows the build-up of the dust cake on the media, meaning the pressure drop remains lower for longer and overall filter life is prolonged.

Another method of maximizing dust holding capacity is how we shape the media in the filter. For example, our bag filters use pockets that are tapered towards the end. These tapered pockets load the incoming dust evenly over the entire surface of the pocket. This means the filter doesn’t become clogged as quickly as U-shaped pockets, which feed the air through the end of the pocket only.

That’s just a small snapshot of the work that we do to maximize the life of the filters that you receive. But what can you do?

Maximizing life and value

Stop watching the clock

Many filters are replaced after a set period – such as six months or a year, typically when the service team makes its scheduled visit. But this rigid approach does not take into account the performance of different filters and the various environments in which they operate. Over a set period, the filters in one building may be loaded to the brim with dust, while another set of filters is virtually clean. It all depends on the level of incoming particulate and the capabilities of the installed filters. So, make checking the system pressure drop part of the regular maintenance routine. If the filter has exceeded its recommended final pressure drop, it’s time to change. And when looking for replacements, choose filters that are suitable for the level of incoming particulate. Our eco16 Filter Management program can help you find the right filter for your individual operating environment.

Look for robustness

A broken filter is little use to anyone, so conduct regular visual inspections of your filters to identify damage before it causes further issues. When replacing filters, look for design features that add robustness to the filter. Plastic or metal frames are usually preferable to cardboard. Grids or guards can help protect the media. And simple additions like carry handles can stop the filter becoming damaged during installation and lengthen its service life accordingly.

Check the capacity

Most manufacturers will detail the dust holding capacity of their filters in the product literature. If they do not, ask them for the data. An air filter with a higher dust holding capacity is the simplest way to maximize the life of your filter system and minimize your costs.