HILLSBORO, Ohio - Seal-Tite Duct, Pipe and Fittings hopes to have an ace up its sleeve with a new antimicobial steel, Seal-Tite Rx, for its duct and fittings.

HILLSBORO, Ohio - Seal-Tite Duct, Pipe & Fittings hopes to have an ace up its sleeve with a new antimicobial steel, Seal-Tite Rx, for its duct and fittings.

Michael Kelley, chairman/ceo of Seal-Tite, said the new product launch was in December and debuted at the AHR Expo in January in Atlantic City, N.J. However, like any new product, demand will generate only as the public - including home builders and consumers - come to know the advantages.

Seal-Tite isn't the only fabricator offering the new coating. It's now available in all McGill AirFlow (Groveport, Ohio) duct and fitting types and sizes. Standard materials are G-60 galvanized and S304 stainless steel. McGill calls SilverGuard "the perfect solution for ensuring indoor air quality" and has been exhibiting the products, most recently at the Affordable Comfort Conference & Trade Show in Cincinnati in April.

AK Steel, Middletown, Ohio, only recently began marketing this steel with an antimicrobial compound for use in hvac ductwork. AK Steel launched the product last year after it registered this use of AgION antimicrobial coating with the Environmental Protection Agency.

As for the fabrication process, Kelley said there isn't much difference except when it comes to spot welding. Riveting or other methods may be used instead, he said. The ductwork has a bluish tint on the inside and a clear coating on the outside too, which helps prevent gouges and scratches. The coating will "migrate" across scratches of a quarter inch or less. The coating is used on fittings as well as the duct itself.

"Interest was phenomenal when we first started to unveil it, now we have to convert that interest to orders," Kelley said. But indoor air quality and home comfort are hot issues now that won't go away, so he feels strongly that the demand will grow.

The AgION coating is described as a long-lasting, inorganic material that contains silver - "a safe and natural antimicrobial agent that has proven successful in controlling the growth and spread of a broad range of microorganisms such as bacteria, mold and mildew."

As for cleaning, McGill offers the following advice: "To clean a SilverGuard antimicrobial surface, apply a mild detergent with a soft sponge or cloth, rinse, then air dry. There's no need to apply harsh or abrasive cleansers. They should be avoided to prevent coating damage. Small scratches on the coating won't affect SilverGuard's efficacy. The active silver ions bridge the gap and migrate to the bacteria or microbes within the scratch. Touch-ups are easily made using SilverGuard epoxy paint."

Many uses

Antimicrobial-coated steels are effective in a variety of industries and applications - from heating/ventilation and air conditioning, food equipment and food processing to construction, appliance and medical equipment.

According to AK Steel, the Food and Drug Administration has recognized the AgION antimicrobial compound as an acceptable additive in all food contact polymers, and the National Sanitation Foundation has certified the compound for food contact and food zone applications.

A model home incorporating the coated steel was built in Santa Susana Knolls, Calif. last year (featured in Snips May 2001). The 11,000-sq.-ft. home, including its stainless steel roof, contains about 30,000 lbs. of steel, coated and uncoated.

AK Coatings allows manufacturers to obtain antimicrobial coatings on all carbon and stainless steels through shop coaters, paint formulators and coil coaters. The silver ion-based antimicrobial suppresses the growth of a broad array of destructive microbes including bacteria, molds and fungi. Antimicrobial-coated steels enhance stain, corrosion and odor resistance and bring an added measure of cleanliness to an application.

Kelley said his 102-year-old company has offered the new Seal-Tite Rx as a no-charge item on select projects, just to generate interest and introduce the product to engineers and builders. As for cost, he said the coating can add from 30-50% to typical 26 ga. ductwork - "That sounds like a lot at first, but it's really not when you consider the cost for a 3,500-sq.-ft. home," he said. Since ductwork is a relatively modest portion of a home's construction cost, that percentage could translate into an additional $800 or so.

Many home builders, Kelley points out, have no trouble selling "up" when it comes to appliance upgrades and granite countertops. Hvac systems have lagged, he said, on offering similar such upgrades to consumers. There is also plenty of opportunity to sell to hospitals, schools and jails. Seal-Tite is quoting on several of these, as well as a large apartment complex in Texas, in a humid area that is subject to mold growth problems.

Seal-Tite has 135 employees and generally sells east of the Mississippi, although it occasionally ships as far as Idaho and New Mexico. The company positions itself as a high end, high quality "craftsman" type of fabricator; it does no installation. Its ductwork has sealed corners and no gaps, for reduced turbulence, better airflow and energy efficiency.

The coated steel isn't just a new construction option. Kelley said he sees an opportunity for many hvac contractors to upgrade a residential customer's ductwork at the same time they are replacing the home's heating and cooling system. This doesn't necessarily require all new ductwork, he points out, since moisture and mold tend to settle into the horizontal (generally the basement) portions of the ducts, closest to the hvac system, rather than in the vertical risers. "We are seeing some (contractors) selling return air packages along with the new hvac system," he said.

There are also opportunities to replace flex duct and fiber duct in places where those materials have moisture or mold contamination problems, Kelley said.

AK Coatings, launched by AK Steel in March, is a coatings supplier specializing in antimicrobial coatings for steel. For more information, visit www.akcoatings.com.

AK Steel offers flat rolled stainless and carbon steels coated with the AgION antimicrobial compound. With headquarters in Middletown, Ohio, AK Steel produces flat-rolled carbon, stainless and electrical steel products for automotive, appliance, construction and manufacturing markets, as well as standard pipe and tubular steel products. Additional information about AK Steel is available on the company's web site at www.aksteel.com.

To request specifications or Engineering Bulletins on this subject from McGill AirFlow call 614-830-2300, fax 614-836-9981, or visit www.mcgillairflow.com.

How it works

Silver ions are released from the coating, come in contact with microbes and the microbes are inhibited. Monovalent or ionic silver (silver with a +1 charge) has an affinity for hydrogen ions, joining with them on the sulfhydryl groups present in microbes, disrupting electron transfer and respiration in bacteria and other microbes. Other non-ionic forms of silver employ other, equally effective mechanisms, such as catalyzing the interaction of atomic oxygen (O) with the sulfhydryl group resulting in an OH molecule and a sulfur bond that prevents further respiration within the microbe.