DIY testing respirators including PAPRs for Healthcare and for families. Professional Nurse, amateur mask tester.
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2/11 The ZM95S features a semi rigid frame, an elastomeric like cloth seal, and adjustable straps, & very high fit factors. I speculated that these properties make it ideal for reuse. The straps can be tightened and the filter media provides a generous margin for safety. 
2/12 You may have noticed your KN95 says "GB 2626-2019" or 2006. It is required for this to be on the mask to meet the standard. This means the mask maker tested it things such as the particle filtration efficiency (PFE) (%) is ≥95%, the breathing resistance is ≤210 Pa. 
2/12 The design of the Zimi is modeled after the Japanese Shigematsu DD11V. This type of mask uses a semi rigid plastic frame with nose foam and an outer filter with a cloth-like soft seal. This is becoming a popular design in East Asia. 
2/5 2 of the 3 "dome" 95 have very sturdy straps (3M 1860, 1860s) and both of the trifolds(3M 1870+, 3M 9205+) have weaker straps. I would always limit reuse on those two models. However to compare different styles for public use you would need to compare w/ similar straps also. 
2/21 In 2020 CSA was tasked w/ creating a Canadian respirator standard. Leading up to this 3M Canada was the only long established big respirator company and new Canadian mask makers had to obtain NIOSH approval. NIOSH gave priority to US applicants over new Canadian mask makers.
2/9 A local woman built a PAPR buggy. This was made to the specifications of a self proclaimed twitter "expert" who wrote an official looking paper. The baby protection device as made to his specifications had protection similar to a surgical mask. 
2/4 He has never been a good masker, so wanted to try most comfortable N95 I have personally used. 3M VFlex 9105. There is almost no breathing resistance, feels to me like wearing nothing. There was some score deflation compared to my own, but still decent for this style test. 
2/5 Her 9 y/o had a perfect fit on Trident Small. The Airgami Small earloop mask has been his favorite and scored higher than expected for earloops in this minimally adversarial(easier) test. The Airgami is a really neat design and this kid has found it to be quite comfortable. 
2/10 Some have noticed the top headband sliding off the top of the head(actually happened during recent fit test of a kid and that happens to adults wearing headband respirators as well). My solution is to wear a hat or scrub cap and place the headbands on top for securement. 
2/8 Here are individual exercise scores. Turned off it works as a negative pressure respirator using your breath to pull air in through a hepa filter. Powered it senses my breath and actively delivers air to maintain positive pressure. Lowest protection in this mode about 99.98%! 
2/10 The 3M Aura 1870+ is the one of the most commonly used surgical respirators, approved for healthcare use. It is a very good pick but the red rubber headbands not as durable as the braided elastic of 9210+ so take care in limiting reuse. Another post on 1870+ to come soon!
2/24 How do you get these numbers? With a portacount machine. This is a particle counter that measures particles inside/outside of a probed mask during a fit test. The ratio of particles inside vs outside is converted into a numerical score called a fit factor. 
2/9 Vitacore gets very high scores, even up into the thousands on a static test. Not exactly my top pick for your everyday respirator because it lacks nose foam- makes it less comfortable and it has a lot of variation between different testers. Also not smaller than Auras. 
2/21 As I have posted before some of the tests NIOSH performs on these is to make sure the air flow stays at 170lpm to maintain positive pressure and a filter test to see that it is 99.97% efficient. I have confirmed all of these stay at 170lpm with included air flow testers.
2/5 7 year-old-boy tested Pinztec small- same mask as Trident Small but sold for Chinese market. Also very high fit factors- HMFF 123 . No other tests done for him as he found a very protective mask on his first try- off to order some Trident Smalls! 
2/18. A 4-exercise protocol was used to attempt to first stress the fit of the respirator to see how low the bottom was for exposure reduction was, then if it stayed the same, increased, or decreased once no longer challenged. 3-4 exercises is MAX. OSHA style test impracticable. 
2/ I first tried making the nose only mask with the small version of the Alliant Biotech N95(identical to Readimask). Fit factor highly disappointing- only 4.4 on the first try. After taping down the sides on right and left of my face and pressing down on all edges it was 42. 
Let's start with the obvious reason for why I got this mask. It is incredibly protective. To validate its protection, I performed quantitative testing using my Portacount 8038, a special fit testing adapter from Cleanspace and my mask in negative pressure mode(blower turned off). 