Flanders to produce a more efficient, flexible carbon filtration media

Flanders to produce a more efficient, flexible carbon filtration media

By Susan English-Seaton

Washington, NC — A new form of bonded-carbon filtration media — the first carbon-based adsorption system designed for the cleanroom industry — is available from Flanders Corp. as a result of its acquisition of the assets of Enviro Spin-Tech Inc. in April.

The new carbon media, which Flanders has dubbed HMZD (high mass, zero dust), is especially designed for molecular contamination control. It can be formed into rigid, porous structures and will offer several advantages over activated charcoal pellets: longer life between replacements, higher efficiency, eradication of problems of charcoal dust in downstream air, and elimination of post-filters used in standard sorbent systems.

The HMZD is targeted at giga-scale integrated circuit (GSIC) manufacturers, but new products utilizing the technology are also aimed at the pharmaceutical and chemical research industries. Besides filtering makeup air, HMZD is now being used in recirculation systems, point-of-use filtration, such as quick dump wet benches, and minienvironments.

Traditionally, activated carbon has been the material of choice for cleanroom filters. The disadvantage is that it`s very dusty — anathema to a cleanroom environment. “What we did first was to eliminate the biggest problem: the dusting,” says Mark Huza, Flanders` vice president of market development. “The way we manufactured the product was to form the individual carbon granules into a solid sheet, or panel. Because you`ve eliminated the dusting, you`ve eliminated the support screen that the alternative materials require. You also reduce the pressure drop, because there`s a certain configuration loss associated with the presence of the screens.”

Because a uniform pressure is applied during the bonding process, the pressure drop across the entire face of the sorbent media remains uniform. This prevents the coil freeze-ups associated with non-uniform airflow distribution, Huza says. It also prevents the formation of stratification zones common to loose-granule sorbent systems. In addition, these systems tend to have non-uniform flow characteristics, creating zones of higher bed velocities, which reduces the contaminant residence time through the bed. The more uniform airflow distribution of the HMZD filter equalizes the contaminant residence time, ensuring maximum removal efficiencies. Another cause of dusting is sorbent bed fluidization. Huza claims the HMZD system`s uniform face velocity distribution eliminates the high velocity zones which result in sorbent bed fluidization.

Cost benefits of the new system are impressive, according to Huza. The HMZD system incorporates computer-modeled sorbent particles of higher mass than competitive systems for a longer filter life, while maintaining a low pressure drop. Conventional material only lasts a couple of months, says Huza, so air-handling systems must be shut down every two months to changeout — an unacceptable expense for IC makers. He cites a customer who has been using the Flanders system for about two years vs. a competitive loose-granule system which lasted less than two months.

Other cost advantages of the bonded process include lower horsepower costs related to a lower initial pressure drop; the elimination of after-filters, which eliminates the capital cost of a fan section; and operating costs associated with the additional pressure drop. The HMZD filter also helps reduce the number of evacuations associated with non-critical contaminants. Because they`re dealing with potentially hazardous chemicals within a fab, he explains, most fab personnel are taught that if they experience an odor they`re not familiar with, they should evacuate. So there have been many evacuations associated with non-critical contaminants.

“A typical evacuation can cost anywhere from a half million to a million dollars, because when they evacuate, whatever is in process is lost. So it`s not just the fact that you`ve lost the man hours; you`ve lost the value of the product that was destroyed during that evacuation,” Huza says.

To combat four basic SEMI-categorized contaminants, (A) acid gases (B) basic gases (C) condensable organics, and (D) dopants, the company has also developed a universal impregnate — one product that is effective against all of the contaminants. The bonded-carbon filtration media was among the assets Flanders acquired from Enviro Spin-Tech, Inc. (Rillton, PA) in April as part of a $2 million deal.


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