Woodcraft Tech Tip: Air Filtration

Air Filtration: your dust collection system's best buddy

A dust collection system is a vital part of any woodshop environment but it needs some backup to make your shop a healthier place to work. Air filtration systems capture the fine - more dangerous - particles floating in the air. 

For optimum operation, air filtering machines are mounted 8 to 10 feet high near the center of a woodworking shop. They can also be mounted on a high shelf. The goal is to have the machine working at a height where the light dust (and microscopic dust) tends to float in the air.

An air filter should recirculate the air in the shop a minimum of 10 times an hour. To determine the minimum air flow needed, first multiply the length x width x ceiling height as measured in feet and then divide this number by 10.

An easy way to determine when the filters need changed or cleaned is to attach a ribbon to the diffuser or exit port on the back of the machine. When the filters are new and the machine is running this ribbon should be trimmed so that it whips vigorously in the exhaust air. As the filters in the machine become clogged and start to restrict the air flow the ribbon will start to droop on the end and not move as vigorously. This is an indication that the filters need attention.

Disposable pre-filters are slightly more efficient than washable electrostatic filters and can help extend the life of the inner bag filter. Disposable pre-filters can be gently cleaned with a brush attached to a shop vac to help extend their life; however, if you find that you are frequently replacing the pre-filter then the washable electrostatic pre-filter may still be the most economical choice.

Inner bag filters can be cleaned by making a tool using a piece of PVC pipe fitted to a shop vac hose with the end of the pipe plugged and a series of holes drilled in the sides. This will allow the pockets to be cleaned out without the vacuum damaging the delicate bag material.