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Proposed ISO Standard Signals Trouble for North American Filter Market

June 2017

By: Kevin Morrow, Business Development Manager, Kimberly-Clark Corporation, Partnership Products  |   05.30.17

Many North American makers, distributors and users of commercial and institutional air filters may soon lose their say on testing standards through ASHRAE. The organization votes in less than one month on whether to abandon 25 years of standard filter performance testing for a Euro-centric standard that may leave many in the industry scrambling to conduct expensive filter requalification.


ASHRAE 52.2 Standard

ASHRAE Standard 52.2 (Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size) is used to test filters for efficiency and provides a useful tool for evaluating filtration effectiveness. The test measures the fractional particle size efficiency (PSE) of a filter, indicating its ability to remove particles of differing sizes between 0.3 and 10 microns in diameter. A MERV, or Minimum Efficiency Reporting Value, is assigned to the filter based on a minimum PSE. A MERV 1 is least efficient, while a MERV 16 is most efficient.


The original ASHRAE standard was introduced in 1992 and subsequently updated in 1999, 2007 and 2012. The current version of the standard contains an optional appendix (Appendix J, reported as “MERV-A” results), which allows filter makers to subject the filters to extreme loads of fine KCl (potassium chloride) particles prior to testing. This optional step serves to discharge electret-treated filters, essentially removing the mechanism by which these treated filters capture particles at high efficiency.


It is worth noting that factions in the industry were unsuccessful in getting this optional step incorporated into the formal standard. As a result, the filter industry maintained the freedom to manufacture products with the electret media needed to efficiently capture submicron particles at high efficiency while reducing airflow resistance. (Read more on this topic: It’s Time You Learned the Unfiltered Truth.)


ISO 16890 Standard

ISO 16890 (Air Filters for General Ventilation) is used outside of North America to measure filter performance in removing particles of sizes from 0.3-10 microns in diameter. Unlike the ASHRAE Standard, it assigns four ratings or classifications to filters (ePM1, ePM2.5, ePM10 and Coarse) and measures the fractional efficiency of ePM1, ePM2.5, or ePM10, depending on the filter’s performance. This measurement scale reflects the European market, where higher end pocket filters make up a majority of the market.


Also unlike the ASHRAE Standard, ISO 16890 requires all filters to be tested before and after a conditioning step to determine an “average” efficiency. That conditioning step completely neutralizes charged filters of their particle-attracting electret treatment by using an isopropyl alcohol (IPA) vapor. This required step unnecessarily stacks the deck against a fair percentage of filter manufacturers, and attempts to negate the value of charged media, a technology that provides end users good sub-micron filtration while keeping pressure drop low.


This point is critical because ISO 16890 was designed primarily with the European market in mind, where HVAC systems use outside air and are most often equipped with pocket filters that use large amounts of media to reduce pressure drop. This is critical to bear in mind, as systems in North America are primarily equipped to use pleated filters that use less filter media and thus need to have a higher air permeability in order to keep pressure drop low. Undermining the value of charged media takes away a valuable tool for enabling low pressure drop.


Will North American Industry Lose Control?

One concern with replacing ASHRAE 52.2 with ISO 16890 is the lopsided representation afforded to individual countries in shaping the standard. The ASHRAE technical committee responsible for approving and updating ASHRAE 52.2 contains 17 members representing a cross-section of the industry. With more than 100 voting member countries, ISO affords only one vote per country, giving large countries like the U.S. equal weight to smaller countries with much smaller filter industries and far fewer commercial and institutional buildings. Moreover, the North American market will be more likely to be represented by larger companies within the industry, thus reducing the influence and input of the many companies that are have a domestic or regional focus.


North America represents about 40% of the worldwide filter industry but would have a tiny fraction of control over the future of an important industry standard if ASHRAE adopts ISO 16890.


Are Real-World Conditions Represented?

ISO 16890 has been adopted in Europe and other parts of the world, where most commercial and institutional filters are pocket-style filters instead of the pleated filters commonly used in North America. It is geared towards locations where the primary use of filters is in heating and ventilation systems and where air-conditioning is not common.


ISO 16890 uses outdoor air measurement values of PM1, PM2.5 and PM10 to calculate a how efficiently a filter captures particles. The standard assumes that indoor environments contain a great deal of outdoor air.


In North America, virtually all commercial buildings use recirculating HVAC systems and allow for only up to 30% outside air. This means that most airborne particles are generated from inside the space. ISO 16890 does not represent the exposure that filters in North American buildings have to actual particles generated from both outdoor and indoor sources.


ISO 16890 reflects an unrealistic and over-simplified version of the factors influencing particle levels in indoor air. It does not take into account the air exchange rates and type of HVAC systems and filters found in North America.


What Will It Cost?

Adoption of ISO 16890 will force North American filter manufacturers to invest significant capital in re-testing and re-qualifying filters. For large filtration companies with an international reach, this may be an expense that is already being incurred, but for domestic and regional manufacturers, re-testing and re-classifying filters will represent new, fully incremental costs. These additional costs would likely be borne throughout the filter supply chain, negatively impacting the businesses of many manufacturers as well as filter distributors.


Smaller filtration businesses will likely feel the cost impact particularly hard.


Will it Cause Confusion among Users?

The ePM1, ePM2.5 and eEPM10 filter classifications in ISO 16890 imply that filter users would eliminate PM1, PM2.5 and PM10 particles from their indoor air. This is a misleading assumption that does not take into account the activities in indoor environments that create particles. IAQ cannot be predicted with a single-pass filter test. Despite the way it’s being marketed and promoted, ISO 16890 will not improve indoor air quality. In and of itself, it will not reduce PM1 and may confuse filter specifiers or lull them into a false sense of security when it comes to IAQ improvement strategies.


The most effective way of reducing PM1 exposure in North America is through the use of filters with higher PM1 capture efficiency afforded by electret-treated media.


Make Your Voice Heard

The 17 members of the ASHRAE 52.2 Technical Committee meet on June 24 to consider replacing ASHRAE 52.2 with ISO 16890. Kimberly-Clark and many of our business partners do not support this effort. We agree that 52.2 could use some refinement to simplify MERV ratings and make it a better tool for improving indoor air quality. However, adoption of ISO 16890 puts us at the mercy of an international body that does not care about our filter market or filter users.


Let your connections on the ASHRAE 52.2 Technical Committee know where you stand on this important issue. If you’re attending the June ASHRAE meeting, be sure to attend the committee meeting on Saturday, June 24 from 8 a.m. – 12 p.m. in the Renaissance Hotel’s Broadlind 1 Room. You can also join the discussion on LinkedIn’s Air Filtration Systems discussion board.

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