By Debbie Olson, Donaldson Torit Aftermarket Product Manager
Paying to have a premium cartridge filter wet or dry cleaned may seem like a bargain, but is it really? Let’s take a look.
The cost to have a filter cleaned is quite a bit less than the cost of buying a new filter, but the savings are quickly lost when you consider the resulting shorter filter life and lower efficiency caused by the cleaning. Typically a cleaned filter tends to last approximately half as long as new filters before they plug again. As a consequence, cleaned filters need to be replaced more frequently, and that means more change outs, more downtime, and more cleaning charges.
Scanning Electron Microscope (SEM) images below (see Figure 1) show the true difference between new premium efficiency media and media after it has been wet cleaned or dry cleaned.
As you can see, the cleaned filter media still has particles clinging to it. Independent laboratory tests* comparing new filter media to cleaned filter media revealed the following:
- Cleaning leads to the weakening of the filter media, resulting in reduced tensile strength, shorter life, and potential structural failure.
- Cleaning often leads to damage of the media pores, resulting in greater depth-loading and reduced filter life.
- Cleaning causes a degradation of the fine fiber surface layer, resulting in reduced efficiency at the submicron level – up to 18% reduction at 0.8 microns.
- Cleaning offers only a partial recovery in overall filter capacity (dust holding ability) reaching only about 52.8%. In the filter elements tested, over one half of the filter’s life is already used up.
- Wet cleaning processes can remove the flame retardant treatment in filters that were treated to be flame retardant.
- More aggressive cleaning processes can create weak spots or even generate holes in the media.
These calculations do not take into consideration disposable safety equipment, travel time for service personnel or the cost of downtime which would all be 2x when using cleaned filters.)
By the end of the year, this average scenario shows that it is actually more expensive to use cleaned filters than new filters. Why spend more money just to compromise the integrity of your dust collection system?
Plus, keep in mind these other factors regarding filter cleaning:
Turnaround time for getting filters cleaned can be as much as two to three weeks.
A spare set of filters and packaging needs to be available for use while filters are out being cleaned.
The shipping and handling required when sending filters out to be cleaned increases the potential for damage to the filters in transit. Experience suggests 10-15%
Cross contamination of filters can occur while being cleaned.
There is a potential to receive back another customer’s cleaned filter, contaminated with their operation’s particulate.
Contaminants can to migrate from the dirty side of the filter to the clean side of the filter during cleaning. This can lead to introduction of the contaminant into the plant environment, after reinstallation.
Dry cleaning companies reserve the right to replace damaged or uncleanable filters with new standard grade filters at the customer’s expense. They will replace premium efficiency filters with a lesser product.
Mixing “cleaned” and new filters in a collector with negatively affect overall loading and efficiency.
Here’s what we see with the naked eye:
One of the most dramatic differences between a new filter and a dry cleaned filter is charted below:
This test data clearly shows dry cleaned filter lose almost 53% of their original dust loading capacity. In other words, cleaned filters provide less than half the filter life performance of new, clean, premium performance filters.
So our word to the wise is to think twice before cleaning your dust collector filters. What might appear to be a good deal often is not.
