3 ms·

Axial fans, especially those for household purposes do not offer the required pressure drop of approx. 300 Pa (https://en.wikipedia.org/wiki/HEPA#Specifications

by chopin 13y ago

Axial fans, especially those for household purposes do not offer the required pressure drop of approx. 300 Pa (https://en.wikipedia.org/wiki/HEPA#Specifications https://en.wikipedia.org/wiki/HEPA#Specifications). Axial fans have typically a high throughput but low max pressure difference (see eg. http://www.adrianagarcia.me/wp-content/themes/twentyeleven/axial-fan-curve http://www.adrianagarcia.me/wp-content/themes/twentyeleven/a...). HEPA filters require radial (or centrifugal) fans for acceptable throughput. As well, a HEPA filter becomes clogged very rapidly without appropriate prefilter. This means that the pressure drop required increases considerably definitely beyond reach of any household fan.

Havoc 13y ago
>Axial fans, especially those for household purposes do not offer the required pressure drop of approx. 300 Pa It might fall short of the official specs, but its difficult to argue with their results. What kind of prefilter would one need? I'm thinking of DIYing this...
- chopin 13y ago
  >It might fall short of the official specs, but its difficult to argue with their results. For this one would need to know the exact measurement setup. For real world performance it is important to know the approximate exchange rate of air of the room. The throughput of the fan across the filter must be considerably higher than that. >What kind of prefilter would one need? I'm thinking of DIYing this... First of all, you would need a radial fan to overcome the required pressure drop. As for the prefilter, I am from Europe, which has probably different standards than the US, but some overview is provided here: http://www.filtration-engineering.co.uk/air_filter_testing.htm http://www.filtration-engineering.co.uk/air_filter_testing.h... . For my clean room set up I had a EU5 prefilter combined with a EU9 main filter. Afair, laminar flow boxes for dirty environment (i.e. not supposed to be used within a clean room) have EU5 (or the equivalent) prefilters as well.
  - Havoc 13y ago
    Interesting. Why do you have a clean room if I may ask? I'm guessing data recovery?
    - chopin 13y ago
      I was in making photographic (those with silver halide) plates in the 90's. That's a wet chemistry process which does not tolerate any dirt in the final product. I made a good deal of the required machinery on my own so I have some basic knowledge on clean room design (albeit a bit rusty).

by chopin 13y ago

Havoc 13y ago

>Axial fans, especially those for household purposes do not offer the required pressure drop of approx. 300 Pa It might fall short of the official specs, but its difficult to argue with their results. What kind of prefilter would one need? I'm thinking of DIYing this...

chopin 13y ago
>It might fall short of the official specs, but its difficult to argue with their results. For this one would need to know the exact measurement setup. For real world performance it is important to know the approximate exchange rate of air of the room. The throughput of the fan across the filter must be considerably higher than that. >What kind of prefilter would one need? I'm thinking of DIYing this... First of all, you would need a radial fan to overcome the required pressure drop. As for the prefilter, I am from Europe, which has probably different standards than the US, but some overview is provided here: http://www.filtration-engineering.co.uk/air_filter_testing.htm http://www.filtration-engineering.co.uk/air_filter_testing.h... . For my clean room set up I had a EU5 prefilter combined with a EU9 main filter. Afair, laminar flow boxes for dirty environment (i.e. not supposed to be used within a clean room) have EU5 (or the equivalent) prefilters as well.
- Havoc 13y ago
  Interesting. Why do you have a clean room if I may ask? I'm guessing data recovery?
  - chopin 13y ago
    I was in making photographic (those with silver halide) plates in the 90's. That's a wet chemistry process which does not tolerate any dirt in the final product. I made a good deal of the required machinery on my own so I have some basic knowledge on clean room design (albeit a bit rusty).