Keeping people safe in both their workplaces and their homes relies heavily on preventing airborne transmission and inhalation of particulates that can cause disease or cancer or irritate sensitive linings and parts of the body. As tested by the Environmental Protection Administration, there are several different air cleaning methods available for commercial HVAC systems. Choosing the right one requires an understanding not just of the particulate and microbial transmission rates, but also the amount of air pressure and air volume your system must provide.
HEPA filters are exceptional in terms of particulate absorption, able to capture more than 99.97 percent of all debris smaller than one micron (or micrometer) in diameter. However, while HEPA stands for high-efficiency particulate air filter, there are different ratings available.
HEPA filters are grouped by MERVs, or minimum efficiency reporting value. It can be somewhat confusing, as the ratings are not based solely on filtration efficiency, but efficiency at certain-sized particles.
Electrostatic filters and ionizers charge particles as they move through the air, using electrical forces to assist the removal of certain materials from the air. The key difference between the filters and ion generators is that electrostatic filters operate as a capture type filter within the HVAC system’s air stream and an ionizer generator allows particulates to clump and therefore be captured by standard filters with lower MERV ratings.
Another key difference is that ionizers must be carefully considered because if not operated or selected properly, ozone is a potential byproduct.
Activated carbon filtration systems are usually used to supplement other filtration systems in circumstances where fumes and odors are particular issues in the workplace. The carbon helps to capture odor-causing compounds like sulfites and others.
The advent of the coronavirus pandemic has highlighted the need for germicidal treatments as part of indoor air quality (IAQ) measures. UV-C light is a compelling option that does not restrict airflow and can help to render bacteria and some microbes inactive.
There are two principal questions when considering in-duct air filtration systems: the interior air quality requirements and amount and type of pollutants to clean versus the amount of air that the filtration system needs to be able to clean. For example, high MERV HEPA filters are great for hospital operating theaters and semiconductor clean rooms but will have more restricted airflows than other filtration systems. This higher air restriction may tax existing fan and electrical systems.
In fact, multiple stages of filtration are often required based on the particulate profile of a facility as well as the ASHRAE standards for ventilation based on occupant activity. It’s important to consider how much air a filtration system can handle (CFM and static pressure loss).
Ideally, a commercial HVAC system will rely as little as possible on floor filtration systems for a variety of reasons. They are usually designed to be temporary additions to spaces and as such are not usually accounted for in terms of airflow measurements and calculations.
Exceptions do exist, and a facility manager may desire or require standalone air cleaning methods for supplemental air cleaning, temporary fabrication projects on a shop floor, a breakdown in the overall HVAC system, or other similar problems.
Windy City Representatives represents leading air cleaning brands for HVAC applications, and we understand how important it is to take multiple considerations like budget and existing systems into account when specifying these units. Call us today for more information: (630) 590-6933.
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