Standard Test Method for Chemical Assessment of Air Cleaning Technologies

Importancia y uso:

5.1 Historically, portable air cleaners were designed to remove airborne particles. More recently air cleaners have sought to also remove chemicals or airborne pathogens, or both. Concurrent with market development, there have been a range of test methods created to examine the removal or production, or both, of particles and chemicals by portable air cleaners in rooms.

5.2 AHAM AC-1, passed in 1988, examines how portable air cleaners remove tobacco, dust, and pollen particles in the 0.1 µm to 11 µm range. Importantly, this method introduced the concept of CADR as a metric to compare air cleaner performance. The CADR determined from AHAM AC-1 is commonly reported by manufacturers on their products in the marketplace. The United States Department of Energy uses AHAM AC-1 CADR values to determine air cleaner energy factors (particle CADR/Watt) that portable air cleaners are required to meet in the United States (10 CFR Part 430). These requirements do not apply to devices that do not move air (for example, whole room germicidal ultraviolet devices). In 2022, AHAM AC-4 extended CADR performance metrics to a series of challenge chemicals. Other test methods have also been developed to determine various air cleaner chemical and particle removal rates, including JEM 1467 (Japan), GB/T18801 (China), NF EN 16846 (Europe), and NRCC-54013 (Canada).

5.3 There is also a history of methods to evaluate potential oxidative emissions from air cleaners. The air quality portion of UL 867, first approved in 1988, describes measurements and sets a limit for the ozone concentration emitted at the exhaust of a portable air cleaner. UL 867 is the only portable air cleaner test method that is currently directly cited by a regulatory body in the United States. AB 2276 limits the sale of portable air cleaning devices in the state of California to those that emit less than 50 ppb_v ozone concentration when tested with UL 867. First passed in 2016, UL 2998 uses the same test method approach as UL 867, but lowers the acceptable ozone concentration to 5 ppb_v. ASHRAE 62.1 requires any air cleaning devices used to meet UL 2998. Both methods assume the ozone is created internally to the device; they do not measure other potential chemistry byproducts and do not determine generation rates.

5.4 This test method determines if a portable air cleaner impacts indoor air chemistry in a positive or adverse manner. Oxidation and ionization chemistry can result in a series of reactions and a range of intermediate chemicals but often leads to formaldehyde and ultrafine particles as final reaction products. Hence, subjecting portable air cleaners to a standard range of challenge chemicals and particles, and examining potential production of oxidation chemicals (ozone, NO_x) and byproducts (formaldehyde and ultrafine particles) is a way to characterize the impact portable air cleaners have on indoor air chemistry.

5.5 This test method seeks to test all portable air cleaners in a uniform, technology-agnostic manner while capturing air cleaner-initiated chemistry that may occur internally and externally to the tested device.

5.6 It is important that air cleaners are tested at room scales so that wall effects (reactions and sorption) and time for chemistry to occur are roughly the same scale as real-world applications. Room size (full-scale) test chambers are used to measure emissions of volatile organic compounds (VOCs) from a wide range of products including building materials (for example, Test Method E1333, Practice D6670) and portable air cleaners (UL 867, UL 2998, AHAM AC-1, AHAM AC-4). This test method uses chambers that are on the same scale as these tests to allow existing testing infrastructure to be used.

5.7 In addition, it is important that air cleaners are tested at chemical concentrations that are relevant to indoor environments (for example, challenge chemicals-to-oxidant ratios are what would be seen in indoor environments) so byproduct reactions proceed in manners similar to those observed for typical indoor spaces. This test method challenges air cleaners with six chemicals at typical indoor concentrations. Ozone and limonene are both added to the chamber to simulate ozone oxidation chemistry and resulting reactive species as seen in a typical indoor space.

5.8 This test method does not account for aging of the filtration material or technology. Aging may significantly impact the performance of some filtration material or other technologies. Due to a current lack of consensus on rapid aging methods relevant to all filtration technologies, this test method does not require aging.

5.9 This test method produces CADRs and generation rates that could be incorporated into certification or other standard organization structures. These include CADRs for the six challenge chemicals and the challenge ultrafine particles, along with generation rates for ozone and formaldehyde, and quantification of ultrafine particle production.

Subcomité:

D22.05

Volúmen:

11.07

Número ICS:

91.140.30 (Ventilation and air-conditioning systems)

Palabras clave:

air cleaner; clean air delivery rate (CADR); generation; ozone formaldehyde;