Certain dust collector filters, including HEPA air filters, electrostatic precipitators (ESP), pleated bag filters and cartridge filters, work best with specific applications. HEPA and ESP can capture the smallest dust particles that you may not even notice, but that can cause serious damage. This respirable dust can penetrate deep into the tissue of the respiratory system, past the body’s mucous and other natural defenses. Inhalable dust is a bit bigger and does get trapped by the body’s filtering mechanisms, but is still not good to be breathing in. For this atmospheric dust, you need filters made to capture the tiniest particles.
When looking at the efficiency of air filters, keep an eye out for ASHRAE compliant filter media, the industry standard in describing filter efficiency based on different particle sizes. Founded in 1894, ASHRAE is an international organization advancing heating, ventilation, air conditioning and refrigeration to serve humanity and promote a sustainable world through research, standards writing, publishing and continuing education.
An ambient air cleaner for light atmospheric dust in breathing zones only requires finely woven HEPA filters, which capture 99.97% of particles 0.3 microns in diameter according to ASHRAE testing. However, in industrial dust collection coarser pre-filters are needed to remove bigger particles of tooling dust, wood cutting dust, etc., before the air is moved through a more delicate HEPA filter. In industry, HEPA filters are best used as post-filters on a multiple filter dust collection system. Also, most ESP, which usually use HEPA after-filters, are best for ambient air cleaning of smoke and mist; though, extremely large electrostatic precipitators, or electronic air cleaners, are used to remove fly ash in smoke stacks. Your home furnace may use electrostatic filters, which can be washable and reusable.
For industrial dust collection, extended media filters are the norm, which include pleated bag or cartridge filters that come in all shapes and sizes. These are often washable, highly efficient across a broad range of particle sizes, and capable of heavy loading due to their great surface area and layers of deep pockets made of woven fabric to pack away heavy dust loads. Huge banks of cartridge filters can be used to continuously collect dust from a factory’s central dust collection system.
