By Morgan Polen
A disturbing trend has been noted for several years, enough that I would like to ask contamination control users worldwide about high-efficiency particulate air (HEPA) and ultralow-penetration air (ULPA) filter life duration and replacement frequency.
Companies report replacing HEPA filters frequently. One company recently reported filter failure after one year. And in one country a local regulation requires filter replacement every three years.
Are you or anyone you know experiencing short HEPA filter life?
When I first got involved in cleanrooms in the 1980s, terminal HEPA/ULPA filters lasted for the life of the facility. Some of the facilities I was involved with in the 1980s are in operation today – some with the original HEPA filters. In fact, an aerospace cleanroom with unidirectional airflow built in the 1960s and still in operation has replaced filters only twice. (Upstream air handling systems with good filtration are really important). It’s always been my understanding that you replace filters if they are damaged, leak, and you don’t want to fix them. For instance, the pressure differential or the uniformity of velocity is too great across the filter or the filter can’t deliver the desired airflow. What, if anything, has changed?
Next month, IEST will provide HEPA filter and testing training. Please consider joining a panel of experts on Nov. 16 as they discuss real-world HEPA and ULPA filter testing and problem scenarios. Many of the panelists worked on IEST-RP-CC034.5: HEPA and ULPA Filter Leak Tests, a recommended practice developed and first published in 1999 by IEST – and just revised in July. The panelists have more than 100 years of combined experience with filter leak testing. Learn more about attending IEST’s HEPA Filter and Testing Workshop in person or virtually.
Morgan Polen is the principal consultant for Microrite, where he uses his 30 years of experience working in cleanroom design, construction, validation, monitoring program development, particle counter design and product management for cleanroom-related products and systems.