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Asit Kumar Mishra
@akm76.bsky.social
Engineer, Researcher. Working towards healthy indoor climates in sustainable buildings. Putting occupants first.
74 followers79 following30 posts
AKakm76.bsky.social

We need clean air to breathe - This is one of those things that everybody "knows" and then no body cares.

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AKakm76.bsky.social

As winter gets upon us and colder, I wrote a piece listing some simple, easy and quick to take steps that can help save energy and ensure comfort. www.rte.ie/brainstorm/2... Hope it is helpful!

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Reposted by Asit Kumar Mishra
Sspid.bsky.social

Very good 🧵 on how respirators work (many of my followers know already.) And also on filtration of rooms. Wish I could bookmark this to give to misinformed souls and bots.

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AKakm76.bsky.social

In another scenario, if the first filter has an efficacy of just 15% and allowed a flow of 1200 cubic feet per minute, it would give us 180 cubic feet of clean air, as opposed to the 199 from the second one. 20/

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AKakm76.bsky.social

The big difference is the bigger flow allowed by the first guy more than makes up for its lower effective filtration. That is why we want to check CADRs and not just effective filtration. 19/

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AKakm76.bsky.social

So, every minute, the first guy delivers 1000 cubic feet air, 70% likely to be clean. So that is about 700 cubic feet clean air every minute. The second guy delivers 199.8 cubic feet clean air every minute. 18/

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AKakm76.bsky.social

Hypothetical time. Say, there is a filter which picks out stuff you don't want with 70% probability. Another, filters the stuff out with 99.9% probability. Every minute, the first lets 1000 cubic meters of air pass through, the second lets 200 cubic meters of air pass through 17/

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AKakm76.bsky.social

The CADR tells you the overall impact, taking into account how good the filter's efficiency is in the size range of concern and the flow rate through the filter. 16/

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AKakm76.bsky.social

That sounds complicated. Which is why we talk about something called clean air delivery rate. Depending on the size of the pollutant of concern, a CADR can be calculated, following some standards (ahamverifide.org/ahams-air-fi...) 15/

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AK
Asit Kumar Mishra
@akm76.bsky.social
Engineer, Researcher. Working towards healthy indoor climates in sustainable buildings. Putting occupants first.
74 followers79 following30 posts