Fabric & filter efficacy testing about ragmask HOT 17 OPEN

Current equipment:

• (2) PerfectPrime AQ9600, PM 0.3/2.5/10 Μm Air Quality Particle/Dust Detector/Counter
  https://www.amazon.com/gp/product/B071RF6B2Y/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

• Festool sander and vacuum (maybe for quick & dirty dust creation per http://www.fwwa.org.au/Art005_WoodDust_c1.pdf pg 7)

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Filter Testing Apparatus 1.0

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Apparatus rough layout:
-dual particle counters
-dual valves suggested by Bill
-pre/post filter flow/pressure measurement
-use of polystyrene microsphere particle solution
-aerosolized particles with nebulization

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Revise setup with anemometers and additional valve.

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Other filtration setups seen on web...

https://www.nbcnews.com/health/health-news/making-your-own-face-mask-some-fabrics-work-better-others-n1175966

https://www.businessinsider.com/homemade-mask-using-hydro-knit-shop-towel-filters-better-2020-4

https://nypost.com/2020/04/04/shop-towels-filter-better-than-t-shirts-for-diy-coronavirus-masks/

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TESTING EQUIPMENT RENTALS
www.eco-rentalsolutions.com

Fit Testers
TSI 8030 Portacount Pro Respirator Fit Tester
TSI 8038 Portacount Pro Respirator Fit Tester
TSI 8040 Portacount Respirator Fit Tester
TSI 8048 Portacount Respirator Fit Tester with N95

Particle Counters
TSI 9306V2 Aerotrak Handheld Particle Counter - 0.3-1 micron range
TSI 8525 P-Trak Ultrafine Particle Counter - 0.02-1 micron range

Particle Generator - NOT LISTED FOR RENT, but Suay Sew rented one (see photo)
https://www.tsi.com/products/aerosol-generators-dispersers/polydisperse-generators/particle-generator-8026/

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Added valve per Bill's suggestion

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Cyclone and Dust Collection Research
https://billpentz.com/woodworking/cyclone/cyclone_plan.cfm#air_volume
"For fine wood dust such as created when using fine sandpaper, we only need about 50 FPM airspeed to overcome normal room air currents and move this dust. For typical sawdust we need to move the air at about 3800 FPM and for larger chips we need to move the air at about 4500 FPM. Ideally we should move right at 4500 FPM airspeed for picking up the normal range of wood chips. Many air engineers design instead at 4000 FPM because this airspeed is ample to pick up the material most fire marshals consider dangerous."

Power ratings of a mid range Festool dust extractor:

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Simple Testing setup using single particle counter
https://github.com/jcl5m1/ventilator/wiki/Material-Filter-Testing

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https://smartairfilters.com/en/blog/ultimate-guide-homemade-face-masks-supplemental-data/

How the testing worked
Smart Air aimed to mimic the test setup used by Cambridge University researchers, known as a Henderson apparatus​, in which a fan blows air and particles through the mask material. The materials were tested for their ability to filter large-sized (1 micron, similar to the size of the Ebola virus) and small-sized (0.3 micron, the size of the smallpox virus) particles and for their breathability factor. For reference, COVID-19 coronavirus particles measure 0.06-0.14 microns in size, but 5-10 microns when in droplets.

First off, we used ambient air pollution for our tests. The air we breathe contains thousands of tiny particles, some of which are the same size as viruses. We did this so as not to have to work with any nasty viruses or bacteria. We lined two fans up in series to generate a strong airflow, enough to blow through each material at 0.3m/s. That’s similar to speed of the air when exhaling through your mouth.

At the end of our test tunnel, we placed a 10cm x 10cm specimen of each material on the end of the tube, and adjusted the fan to measure 0.3m/s on our anemometer. For some thick materials, our two-fan setup wasn’t powerful enough to reach this speed. Our results reflect which materials these were.

After setting up the material and the airflow, we then proceeded to use our Met One GT521 laser particle counter to measure the number of particles the materials could capture. Met One is the company that makes the big BAM monitors that most governments use to measure air pollution, so we’re in good hands here.

We tested the particle capture effectiveness of each material at capturing 1.0 micron and 0.3 micron particles. The 1.0 micron size mimics the Bacillus atrophaeus bacteria used by the Cambridge researchers (0.93-1.25 microns in size). It’s also a size that can be considered similar in range to coronavirus droplets (5-10µm). 0.3 micron particles are typically considered the most difficult to capture, and so was chosen here as a ‘worst case scenario’. It can give a reasonable estimate for effectiveness of each material at capturing 0.1 micron particles – the size of the coronavirus when not in droplet form.

For each material, downstream air was samples for 30s with and without the test specimen in place, and repeated 3 times. Averaging these values gave us our 0.3 and 1.0 micron capture effectiveness for each material.

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Relative calibration of our particle counters. Used smoke from candle for particulate matter. Counter A averages ~22% higher reading than Counter B in the 0.3 micron range.

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Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks - single layer and multi-layer hybrid testing

https://pubs.acs.org/doi/abs/10.1021/acsnano.0c03252?fbclid=IwAR0PqrJJ71EYncJZdlQRLMz0ULgU2mR0JwQIkJ8yUvoZlStVr4vQMERnTNQ#

Material Testing Study.pdf

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