The purpose of air filters is to protect the moving parts of an industrial air intake system. What you want to accomplish with your filters will determine the type and number of air filters your system will need.

If you want to solely protect the moving parts of your air intake system, then a disposable air filter will do the job.

If you want to have good Indoor Air Quality (IAQ), then you will need a pre-filter and a final filter. The pre-filter will capture large particles and allow the final filter to do its job – capture the finer particles (allergens, dust, smoke, etc.) that will result in better IAQ.

If you need even finer filtration, then you can have several pre-filters before the final air filter. This type of situation would be more likely to occur in cleanrooms and a paint operation in an automotive factory.

The ultimate goal of having a pre-filter is to extend the life of the final filter, since final filters tend to be more expensive.

Helpful Air Filter Maintenance Record Chart:

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Prefilter: Initial Resistance ______ " w.g. Final Resistance ______" w.g.
Description ________________________________ Size _______________

Final Filter: Initial Resistance ______ " w.g. Final Resistance ______" w.g.
Description ________________________________ Size _______________
Grease ______________ Size _______________ Other ________________
Belt ___________________

Key: PFR = Pre-Filter Resistance; FFR = Final Filter Resistance; TR = Total Resistance; CB = Checked By; G = Grease; B = Belt

Air Filter Maintenance Record Chart Courtesy of R.P. Fedder Corporation