The ASHRAE 52.2-2007 Standard in Air Filtration

10 minutes to read

ASHRAE is the American Society of Heating, Refrigerating, and Air-Conditioning Engineers that was founded in 1894 that works to advance the arts and sciences of heating, ventilating, air-conditioning, and refrigerating. They are an international organization of 50,000 people. They have developed a standard for the world to know what filters are best.

“They publish standards that fit under one of the following three headings:

  1. Method of Measurement of Test
  2. Standard Design
  3. Standard Practice

ASHRAE Standard 52.2-2007 – Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size has been universally accepted and used to evaluate product alternatives. It is a consensus standard accredited by the American National Standards Institute (ANSI) developed and published to define minimum values or acceptable performance. The standard is also one that is under a program of continuous maintenance.” Source.

January 2008, the committee at ASHRAE decided to review and improve the ASHRAE 52.2-2007 test standard for air filters and cleaners. They made two changes.

The first change required the mandatory calculation of dust holding capacity and arrestance to be changed to the 52.2 standard. Before, it was a 52.1-1992 standard that included a value called dust spot efficiency. Instead of using dust holding capacity and arrestance to determine the MERV value, now only the arrestance will be used in this determination for any filters less than 20% (which is MERV 1 through 4).

The second change was that instead of using 30 grams loading of ASHRAE dust as the conditioning step, the filter being challenged will use a KCl (potassium chloride) conditioning method that closely mimics the aerosol size particle distribution that most filters experience in “real-life” conditions. This idea is to implement a more accurate reading of the filter’s abilities for the people to understand. They did not think the previous standard was  nearly accurate enough. “In fact, the 1999 version stated, ‘Some fibrous media air filters have electrostatic charges that may either be natural or imposed upon the media during manufacturing. Such filter may demonstrate high efficiency when clean and drop in efficiency during their actual use cycle. The initial conditioning step of the dust-loading procedure described in this standard may affect the efficiency of the filter but not as much as would be observed in actual service. Therefore, the minimum efficiency during test may be higher than that achieved during actual use.’” Source.

The new standard was approved and formally published in fall of 2008, leading to the implementation of the standard.

There was a research project under ASHRAE called 1189 that showed that the use of the KCl conditioning step was very accurate in replicating re-life filter performance. Therefore, the newer testing is more important and more relevant to purchasing air filtration products.

Recent tests have shown that the finest airborne particles are the most detrimental to humanity’s health. This means the changes made to the ASHRAE standards are very important when choosing an air filter.

“The ASHRAE 52.2-2008 tests can be submitted and performed at several independent testing laboratories and select advanced air filter manufacturing company test facilities.” Source.

“MERV 1-4 filters are used primarily to protect equipment… MERV 6-16 rated air filters are used to protect people from harmful airborne contaminants that may affect health, productivity, and lifespan. When considering proper air filter selection it is important to keep in mind that two trends are dramatically changing filter selection from just a few years ago.” Source.

Some facts to consider:

  • 26% of the US population live within areas that have levels of pollution that have been proven to increase the risk of death from heart attack, strokes, and asthma.
  • “Nosocomial, or hospital infections that patients contract after entering a health care facility for other treatment, are the fourth largest killer in the United States, causing as many deaths as AIDS, breast cancer and auto accidents combined.” Source.
  • A study done of 59,000 women found that women living in the most polluted areas had a 150% increased risk of death from heart attack and stroke.
  • A study of 500,000 people in the US discovered that lung cancer deaths went up by 8% for every 10 micrograms of fine particles per cubic meter of air, heart disease deaths went up by 6%, and all deaths increased by 4%

When you are evaluating air filters, realize that there is a significant difference between MERV and MERV-A ratings. The “A” rating is very important because it means that the product does not decrease in efficiency over its lifetime. Meaning that if the filter you are looking at does not have the “A” rating than that filter will decrease in efficiency as time goes by, even with its supposed life cycle.

Also, be aware that coarse fiber air filters that use an electrostatic charge decrease in their efficiency over time because the charge decreases. Fine fiber air filters have much better efficiency.

Ask your filter manufacturer for actual filter pressure drop performance over time, instead of the initial pressure drop. This will give you an idea of the performance of the product and not just the beginning of its use. Superior performing filters have a longer loading curve which means that they have improved airflow and energy saving throughout the life of the air filter.

The overall cost of ownership should be evaluated, not the initial cost of the filter.

Camfil is known for their superior quality of air filters and their top of the line air filtration systems that provide the best and cleanest air possible, with the greenest option on the market. “Camfil is the world’s largest and leading manufacturer of filters and clean air solutions… We can be found everywhere from offices to clean rooms for sensitive electronics production, pharmaceuticals, mines, factories, hospitals and nuclear power stations.” Source.

Camfil has a strong belief in providing clean air for people around the world. They are a global company with 29 subsidiaries, as well as 23 production plants throughout the world. Despite being so international, they make sure they have local agents available for their customers in every place possible.

“For you as a customer, this means that you stand to benefit from our global knowledge bank and the resources that a world-leading company constantly invests in research and development. At the same time, you stand to benefit from personal contact with your local Camfil office, which will be only too pleased to provide you with the right filter solution for your particular needs.” Source.


Media Contact:

Lynne Laake


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