Material Filter Testing
We got a Fluke 985 Particle Counter, which is a re-branded version of the MetOne HHPC+ Handheld Air particle counter used by hospitals and clean room to evaluate clean room performance. It is a 6-channel filter that simultaneously measures particle detection of 0.3um, 0.5um, 1um, 2um, 5um, and 10um particles.
"Particles in a bio-aerosol are generally 0.3um to 100um in diameter. However, the respirable size fraction of 1-10um is of primary concern." reference
- Each sample was gathered using 2 cycles of 2L measurements. The meter reports Count/L for each of the 6 sizes.
- The meter was last calibrated on 2016-06-24. And the zero count filter was checked at the beginning of each session. We don't have the ability to re-calibrate the meter ourselves.
- An ambient air measurement with no filter was taken before and after each material sample. The average of the before and after samples are used as the baseline to compare the filter measurement. The ambient air quality fluctuated during the process, and this was used to help normalize the readings.
- The inlet of the meter was covered the material sample, and secured with several turns of a rubber band, which held each sample tightly given the lip around the inlet adapter.
N95 respirators provide the lowest level of acceptable protection against COVID-19. Therefore, OSHA now recommends that employers supply healthcare personnel who provide direct care to patients with known or suspected coronavirus with other respirators that provide higher protection than N95s. This includes N99 or N100 filtering facepieces, reusable elastomeric respirators with appropriate filters or cartridges, or powered air purifying respirators (PAPR).
- According to this source, it seems we care the most to filter out the 1-10 micro meter sized particles which the top 3 mask filters do well.
- Where the numbers are negative means the material is dirty and worsened the air quality.
- Every paper towel brand will surely perform differently. Unfortunately we no longer have the packaging of this particular paper towel.
- A friend shared this source (suayla.com) that mentions specific shop towel brands that can provide 87% particle filtration.
For complete details on the raw data, you can check the interactive data set here.
Breathability through these fabric. Measure pressure drop across fabric for which this doc may have hints to give us ideas on how to measure that.