Read on Twitter
When to change the filter on DIY #CorsiRosenthalBox? Holder et al (onlinelibrary.wiley.com/doi/10.1111/in…) showed that performance degradation depends on contaminant: Dust reduces airflow. Smoke kills electrostatic properties. @JimRosenthal4 @joeyfox85 @CorsIAQ 
@JimRosenthal4 @joeyfox85 @CorsIAQ Note the test substance for the CADR PM2.5 performance measurement was simulated wildfire smoke.
The same would likely apply to a commercial HEPA air cleaner. Monitor for clearing time for a fixed release of contaminant with a simple PM meter.
Incidentally, the AHAM standard AC-1 doesn't include a filter loading test. It's separate: AHAM AC-3-2009, Method for Measuring the Performance of Portable Household Electric Room Air Cleaners Following Accelerated Particulate Loading.
The China version of the CADR test (GB/T 18801-2015) includes the same test as AHAM AC-1, but also includes a performance loading test with increasing numbers of cigarettes in increments of additional 50 cigarettes each test (50, 100, 150, 200, etc) until CADR drops by 50%.
@kprather88 uses Purple Air monitors in classrooms to track performance of portable in-room HEPA air cleaners
https://twitter.com/kprather88/status/1321650552392937472?s=20
• • •
Missing some Tweet in this thread? You can try to
force a refresh
