Filter industry is standardizing, hopefully, on a standard


By Hank Hogan

Unlike heads, two technical standards aren’t better than one. That’s a reason given for the end-of-March announcement of the revival, after decades of dormancy, of ISO Technical Committee (TC) 142 covering cleaning equipment for air and other gases. However, a behind-the-scenes reason involves a technology tussle between the US and Europe, with the Continent flexing its muscle. Other players, including potential heavyweight China, have yet to be heard from. It all adds up to a cleanroom drama that could play out during the next five years.

On the technology side, differences in the testing standards of High Efficiency Particulate Air (HEPA) and Ultra Low Penetration Air (ULPA) filters have led to a confusing and costly situation. Since filters sell worldwide, vendors maintain what are essentially two product lines.

“It’s like having metric wrenches and English [US equivalent] wrenches. If everybody could just agree on one or the other, then you’d be able to cut your inventory,” says Philip Winters, director of product development at filter maker Filtration Group, Inc. (Chicago).

The inventory reduction wouldn’t be halved with a unified standard, but Winters notes there would still be some real benefits from having a single international set of tests. One of those could be a decrease in cost.

Under the auspices of the Institute of Environmental Sciences and Technology (IEST; Rolling Meadows, IL), Winters is chairing the US Technical Advisory Group (TAG), which will determine how the US votes within ISO on the completed standard. The IEST announced in mid-April that it was seeking participants for TAG. The standard itself will be the product of working groups. One of those is Working Group 4 (WG4), which will develop a standard for the testing of HEPA and ULPA filters.

The sentiment for a single test is echoed by Seiichi Takizawa, who will be on WG4 and is director of research and development at air filter maker Cambridge Filter Japan, Ltd. (Tokyo). He doubts it will be possible to have a single, unified product, largely because customers in various industries, such as the semiconductor and nuclear industry, have different requirements. “But the test method should be clearly standardized to show the real performance of a filter to our customers,” he says.

WG4 will be chaired by R. Vijayakumar, director of market development at TSI, Inc. (Shoreview, MN), a maker of particle counters and other measurement equipment. Vijayakumar explains that the reactivation of the technical committee and the associated working groups is actually in response to a problem that had been festering in the background: Countries were developing or using their own standards.

Besides adding to cost and complexity, this situation also gives manufacturers wiggle room, allowing them to make a product to meet whichever standard they think is the least rigorous. For example, most HEPA users assume a filter that meets the standard removes 99.97 percent of particulates above a certain size from the air. However, Vijayakumar points out that some standards allow for a HEPA filter to be 85 percent efficient, a deviation from the accepted norm that isn’t spelled out explicitly but is instead a result of the way the standard is written. That’s a distinction that filter buyers may not be aware of. “The consumer thinks a HEPA is a HEPA is a HEPA,” he says.

Vijayakumar notes the first meeting of the working group has been set for May. It’s expected to take three to four years for new standards to be hammered out, voted on, and adopted.

Behind the regional differences in standards-and the current push to change things-lies a bit of history. US testing methods are based on old military specifications, with measurements done using thermally-generated aerosols. These methods and the resulting standards have been around for decades. European specifications, on the other hand, tend to concentrate on particle counter results and are much more recent.

Also much more recent is the European push to revise the standards and harmonize the different documents. When it comes to HEPA and ULPA filters, Rudolf Wepfer, president of cleanroom specialists rw-consulting (Uster, Switzerland), attributes this drive to increasing technical expertise on the Continent and decades of experience with the old standards on the part of the Americans. “The US is much more bound to tradition and seems to have difficulties switching to a new method,” he says.

That European effort to develop its own standards shows up in other areas, according to Jim Walters, director of international standards for the Air-conditioning and Refrigeration Institute (ARI; Arlington, VA). ARI is an industry trade association that develops standards for heating, ventilation, air conditioning, and refrigeration (HVACR) covering, among other things, HEPA and ULPA filters. Walters notes that ARI publishes two new standards a year and revises 17 more. Other organizations are also involved in the effort of producing standards.

In contrast, Walters puts the number of European HVACR standards as having grown from almost nothing 10 years ago to 131 today, with another 60 in development. The production rate is, thus, somewhere around 15 standards a year. If that pace continues, eventually standards of European origin will equal or outnumber those of organizations like ARI.

While standards don’t have the force of law, regulators often turn to them as the basis for implementing regulations and directives. Hence, any new European criteria regarding HVACR may have a far-reaching impact.

The Europeans, however, could run into a countervailing force. China’s influence in this area is still undetermined, but Walters says China has announced an overall goal to introduce 1000 standards into ISO every year. It’s unclear if that will actually happen and how much of that flood of yearly standards will involve areas that concern cleanrooms. Walters notes, though, that the Chinese can’t be discounted for a number of reasons. “They’re important because they have manufacturers and because of their market. So they are a player to be dealt with, reckoned with, and cooperated with,” he says.