Austin Air HEGA vs. HEPA.

I get occasional queries from Austin Air purifier buyers asking for help choosing among the Austins. Many are confused by the acronyms HEGA and HEPA.

For starters, HEGA is not an alternative to HEPA, it's a carbon- impregnated woven cloth that is offered in place of standard granulated carbon for gas and odor filtration.

All Austins have quality true-HEPA particle filters.

It seems designed for environments where gas contaminants are combined with relatively large .9 micron plus particulate - smoke and pollen.

The regular HealthMate has activated charcoal granules and zeolite clay for odors. Zeolite is a cost-cutter.

Austin has had many problems with their long filter warranty and integrated (one piece) filter design.

There are always a few users who clog the carbon with tobacco smoke, paint, ect, and/or get moisture in the zeolite which ruins the filter prematurely.

Acetone in art studios and other paint/particulate situations also challenged the carbon granule filters.

I suspect the HEGA is partly Austin's engineering staff's response to management pressure on warranty claim costs, especially from smokers and fireplace users/neighbors.

Pollen-sensitive customers could also notice shorter carbon filter life as pollen, relatively large particulate, will clog non-HEGA carbon-first filter trains rapidly.

No other builder warrants filters, so they have not seen fit to implement carbon cloth filters.

The Jr Allergy Machine "HEGA" filter weighs 2 lbs. less than the "HEPA" filter. Looks like mostly lost carbon.

Again, note that these are both HEPA filters, only the carbon filter has been changed.

Gas molecules are often attached to micron-range soot particles, especially in the smoking/burning situation.

With granulated carbon first, particles clog activated carbon pre-maturely. Activated carbon, once it traps large numbers of particles, begins to flake off and enter the exhaust air.

This is why, in standard filter trains, gas contaminated air must go through HEPA last.

Normally it's prefilter > granulated carbon > HEPA.

This also means HEPAs tend to emit odors before being fully restricted by particulate.

The carbon cloth does not flake as easily.

So Austin reversed standard filter train order for the HEGA Air Purifiers, moving air over the HEPA first and the carbon cloth second.

Prefilter > HEPA > HEGA carbon cloth.

Now particulate is separated from gas molecules at the HEPA.

The "military" carbon cloth can adsorb the gas without getting plugged up with particles.

The builder claims the carbon cloth can adsorb more gas than the larger weight of granules in the sister machine. I am skeptical that this is true beyond the target applications.

Austin HEGA air purifiers will have longer filter life than activated carbon in high gas-particulate environments, mainly smoking, pollen, and woodburning.

More surface area is available for adsorbtion since fewer particles obscure the carbon surface as the filter ages.

In these high intensity continuous source emission applications, more efficient gas adsorbtion means faster relief.

It could provide longer filter life for the chemically sensitive, since there is always some gas coming through.

Note that particulate emissions and efficiency for residential air cleaners are well quantified, but gas efficiencies are left to more subjective methods.

However note that with the HEGA option there is less carbon present,so the claimed superiority is compromised.

So it comes down to your application.

Smokers could benefit from the HEGA design's longer filter life.

Do you have heavy seasonal pollen, micron and above dust (country roads, residual World Trade Center dust, California wildfires), or smoker/woodstove emissions?

Those appear to be the HEGA target applications.

Paying extra for HealthMate "Plus" gets you potassium permanganate oxidizer, in my opinion worth the money.

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