Coleman Tool & Manufacturing’s new plant use air curtains to separate the interior and exterior atmospheres. It has found it has no supplemental winter heating costs, with significantly less heat loss during open door periods. And, the heated air is re-circulated through the air curtains, which contributes to the company’s environmental management efforts.

Despite the efficacy of the air cleaners, an estimated 20 percent of the smoke still rose up and out of the welding area, creating a haze throughout the plant. Energy savings were important, but not at the expense of IAQ, according to Coleman.

One proposed solution would have added tens of thousands of dollars worth of rooftop make-up air equipment to re-circulate heated air. Instead, Bugner theorized that the air curtains might serve a dual duty as air cleaners and energy savers. The 16-foot height above the doorways was a strategic position to help the air curtains draw in the lofty haze.

Some air curtain manufacturers offer options for conventional filtration add-ons, however Bugner felt heavy industrial welding smoke would need a filter holder designed for quick and frequent replacements to keep labor expenses in check. Also, most conventional fiber filters carry a MERV (Minimum Efficiency Reporting Value) rating of 1 to 6, whereas welding smoke and particulates would need at least a MERV 8 filter--the same rating as the filters used in the welding area air cleaners. “We designed a filter holder we could manufacturer ourselves, required only 10 minutes or less to replace, was aesthetic, didn’t affect the air curtain’s airflow and would use inexpensive off-the-shelf filters,” said Coleman, who has since applied for patents on the filter design to market it to industrial air curtain users needing heavy duty filtration.

Fine Tuning the Filtration
Bugner experimented with different combinations of inexpensive filter media and filter holder styles to further drive down maintenance costs. Since a 24 x 24-inch filter is a standard off-the-shelf size, the steel filter holder was fabricated to allow eight pleated fiber filters for the two 16-foot-wide air curtains (six for the 12-foot-wide air curtain) to be slid into either end in 10 minutes or less.

The filter holder’s metal fabrication, a Coleman Tool specialty, was designed with light weight and rigidity, but also featured an attractive safety grille that also prevented larger items such as hands or other accidental contacts from entering the filter portion.

Bugner also experimented with less expensive filter roll material that could be cut to a desired length. This method required a filter holder with a hinged door for easy access, however it was later decided that aesthetics suffered without the 2x2-foot pleated filter framing to hold the material neatly in place.

The IAQ results have been significant. The haze is gone, the production floor’s air smells fresh, and the plant’s chronic asthma sufferers notice significant breathing improvements, according to Bugner

Coleman executives now believe all industrial buildings should be outfitted with air curtains for energy-saving environmental separation in addition to IAQ filtering reasons. “In our case we had to have air curtains to save energy, so the fact they also boost IAQ is a bonus that carries virtually little additional cost,” Bugner said. “Anyone that thinks they have a clean environment should put up an air curtain with a filter. They’ll find out the air isn’t as clean as they thought.”