Filters: one size does not fit all.

Supreme turns them out with doughnut holes, big, small, even folded over

Behind a Inglewood storefront so old that a painted wall reads, in part, "Oregon 8-3491" lies one of the region's leading manufacturers of custom filters, made to clear air and water for everything from airplanes to submarines, and even secret industrial uses in mainland China.

"Sometime we will work for six months on a filter, making prototypes, and then sell only one," says Richard Kriwanek, 41, president and son of the founder of 57-year-old Supreme Supply Co. Inc., filter makers. "We build prototypes, and send it to the buyer. They send it back for modifications. This is not a high-volume business."

The bread-and-butter of Supreme Supply's business remains the Pentagon, which needs a seemingly endless array of filters to keep air clean for the high-tech armed forces -- in particular, sensitive electronic equipment.

"One week, they need a round filter, 2.5 inches diameter, with a (doughnut) hole in the middle," says Adour Adourian, 48, production manager and engineer at Supreme Supply. "The next week, a filter that must be folded (over), so it can fit through a narrow passageway to its ultimate location."

Typically, the Pentagon, or its network of suppliers, orders filters from Supreme Supply in batches of two to five. Often, new high-tech gadgetry is being grafted onto older planes and submarines, and a filter must be made for the new equipment.

"Orders of more than 100 are very rare around here," says Kriwanek. "Larger than that (100 filters), it is probably better to buy standard-sized filters off the shelf."

Usually, Kriwanek says, the Pentagon procurers do not even tell Supreme Supply in what manner the filter will be used -- only "the specs:" the dimensions of the filter, what it must clean and to what level of cleanliness, and other vagaries.

"One filter we made had to be black, and could not reflect light," says Adourian. "We put a flat black anodized finish on it. It was used to filter air, and placed on the housing for a camera on a reconnaissance aircraft. They didn't want glare off the filter to bother the camera."

During Desert Storm, business quadrupled for eight-employee Supreme Supply, as military men fought to keep sand and dust out of equipment, notes Kriwanek.

But with a businessman's sigh, he adds, "That only lasted three or four months."

Despite the Pentagon's appetite for clean air, the biggest filter Supreme Supply ever made was not for the national defense but for Red China -- six-foot-in-diameter filters, one-foot thick.

The filter's "media" -- the element that actually filters the air, as opposed to the housing -- was stainless steel wool. The casing was also stainless steel, which does not rust. Supreme Supply made seven of the filter behemoths, 15 years ago.

Why such large filters? "I would guess it was a mist eliminator," says Adourian. "Used to take oil or water out of air. We designed it so that media could be removed easily, to be cleaned."

Supreme Supply did not ship the filter to China directly, but to another manufacturer, who used the filter in the end product. "That's how a lot of our business goes," says Kriwanek. "We don't sell to the customer, but to the manufacturer. We don't even know the ultimate user."

The whole China business was a bit hush-hush, as Adourian and Kriwanek recall, but they guess the filters were used in a large factory or hydroelectric plant.

In recent years, filter users, particularly computer chip makers, have become more demanding, wanting specs of dust as small as 0.3 microns, or three-tenths of a millionth of a meter, removed from the air, says Kriwanek.

As more and more manufacturing involves miniaturization of electronic circuitry -- a la the computer industry -- the demand for intense filtration will continue to rise, predicts Kriwanek.

Medical industry people can be picky too.

"There was a 'flying eye surgery' airplane (which ferried eye surgeons about the country) in the early 1980s which needed a very clean environment in one portion of the plane," recalls Kriwanek. "We built for them some HEPA filters." A HEPA filter is a High Efficiency Particulate Air filter, usually made of paper.

In the case of the HEPA filters, Supreme Supply buys the filter paper, or media, from other manufacturers, and then fits the paper into a filter built to specifications.

The modern HEPA filters are a far cry from the first filters ever made, probably in Europe or the Mideast, thousands of years before Christ.

Most likely, man first used skins to filter wine. The modern word "filter" is derived from the medieval Latin word "filtrum," which means felt. Felt was used for straining liquors in the Middle Ages in Europe.

Today, in contrast, many filters are "multi-media" in that they may use urethane foam, polyester or other modern plastics and rubbers to clean air or water.

Other filters are made not to remove particulates, but odor. "Whenever there is a smell problem, usually a sort of charcoal is used, depending on the odor to be removed," says Reuben Yapyyuco, operations manager at Supreme Supply.

The demand for filters is relatively steady (Desert Storm aside), says Kriwanek, because so many are used on existing equipment. Even a slowdown in defense spending will not affect business much, as existing filters clog or wear out, and need replacement parts, he says.

Why, more than 30 years after the old Bell System phased out the old alpha-numeric phone numbers, does Supreme Supply keep "ORegon 8 -- 3491" painted on the outside wall?

"Just for the heck of it," answers Kriwanek. "It shows we are an established, old-time company. I like the sign there."