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HEPA blower matching

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#1 425nm



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Posted 27 April 2019 - 02:47 PM

Greetings Myco-friends!

Been a while since I posted. Life has been busy and with spring happening rather suddenly I had a surge in contamination that out me off my game a bit.


That gave me a nudge to finally get around to acquiring a flowhood. Normally I'm all in for scratch building a thing but it just so happens that a 24x12x12 flowhood popped up on my local classifieds with the cabinet already built for the cost of the same sized filter off eBay. So I nabbed it.

The previous owners construction appears to be fine. Initially they were trying to sell it with an underpowered inline duct fan like you'd use for an MJ grow. I managed to talk them into just selling me the box + filter. Apparently they'd had spotty luck with the setup and I am quite confident it was just a way underpowered fan.

The filter is a Koch BioMAX.
The QA sticker reads:
Penetration 0.013%
Resistance 1.30
Test flow rate 1000CFM

So I understand that you've got to match a blower to a filter by looking the static pressure vs flow rate for each blower. Find one that will output at filter static pressure + that of prefilter no more than 20% over 100'/min*area of your blower.

So 2' x 0.958' = 1.92 'squared * 100FM = 192CFM

192 CFM*0.2 = 38.4

192 + 38.4 = 230.4 CFM

So I need a blower that at a static pressure of 1.5 (1.3 + 0.2 presumed static pressure of pre filter) puts out 192 - 230.4 CFM.

My question is that test flow number. The static pressure was measured at 1000CFM which is waaaaay more than I want. Can I trust that 1.3 number if I'm pushing less air through the filter?
  • Rantrapr, BrantPr, Syndneyunaky and 1 other like this

#2 clumsy



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Posted 28 April 2019 - 01:01 PM

Here is a chart that may provide a clue about reduced static pressure at reduced flow rate.

#3 425nm



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Posted 11 July 2019 - 10:16 AM

For those who may come across this thread in the future. It does indeed make a difference. A big difference. I finally got hold of the manufacturers customer support who got me an engineer. After some number crunching the engineer told me the resistance would be around 0.3 if I were only pushing out 100CFM rather than 1000CFM.

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