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blapporesto
Stranger


Registered: 10/24/16
Posts: 4
Last seen: 2 years, 3 months
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Need help calculating correct blower type for my LFH
#24411826 - 06/17/17 03:20 AM (6 years, 8 months ago) |
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I am trying to loosely follow the instructions for building a laminar flow hood (LFH) found on http://www.fungifun.org/English/Flowhood.
I suppose part of the difficulty lies in doing everything in metric, but livnig in europe, freedom units are hard to deal with.
So far I have an H14 HEPA filter, 610x610x150mm in size. Now I need to figure out what blower I need to buy. Can anyone check my math and maybe give a blower recommendation?
610mmx610mm = 372'100mm2 or 0.372m2
as per Stamets' recommendation, required air speed is 100ft/m, or 0.508m/s
multiplying area x air speed gives the amount of air your blower must deliver at the sum of the STATIC PRESSURE of the HEPA filter + prefilter.
So, 0.372m2 x 0.508m/s = 0.189m3/s.
Converting to m3/h gives 680m3/h.
Now my HEPA filter comes with 2 notable numbers on the data sheet: 2300 m3/h Air Flow (not sure what this means, is this a maximum that can be pumped through?) and a 'Pressure Drop' of 320 Pa. I assume this Pressure Drop is what the Funghifun instructions refer to as Static Pressure.
Assuming this is correct, and that my hypothetical pre-filter would add another 50 Pa, the total Static Pressure I need to overcome would be 320 Pa + 50 Pa = 370 Pa.
So in summary, if my math is correct, I need to find a blower that can deliver 680m3/h at a static pressure of 370 Pa. Do these numbers look alright?
Can anyone point me towards some suppliers, ebay shops, aliexpress listings, anything? I'm having a real hard time finding data sheets with the volumetric flow/static pressure curves for many blowers listed out there on the interwebs.
okeedokee, thankee for your time, and here's hoping for some trich- and penicillin- free monotubs by god (been having some serious contamination issues, hence the LFH build).
cheers
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Crispykoot
Jello Wrangler



Registered: 10/16/16
Posts: 5,922
Loc:
Last seen: 9 days, 7 hours
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Re: Need help calculating correct blower type for my LFH [Re: blapporesto]
#24411924 - 06/17/17 05:42 AM (6 years, 8 months ago) |
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I would get the resistance number of the filter itself from the manufacturer to make sure it is 1 inch or equivelant. I would also ask the manufacturer about the fan needed to achieve laminar flow.
For a filter your size...
"#1 calculate the area of your HEPA filter. In my case, it is 2ft x 2ft = 4 sq. ft.
#2 multiply filter area by desired flow rate. in my case, 4 sq. ft. x 100 feet per minute = 400 cubic feet per minute
this number is the amount of air your blower must deliver at the sum of the STATIC PRESSURE of the HEPA filter + prefilter.
most HEPA filters of this type will be around 1" static pressure, and most prefilters will be around .2", which is the case with my filter from FP. so in my case, i need a blower that can do at least 400 CFM @ 1.2" static pressure"
Your filter is this size. As long as the resistance is the same you should be able to plug your metric loveliness into the formula...
You Euros can do freedom units...Us Canadians manage just fine using both.
--------------------

Shadowboxing the apocalypse and wandering the land
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foragedfungus



Registered: 09/30/13
Posts: 1,851
Loc: out there
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Re: Need help calculating correct blower type for my LFH [Re: Crispykoot]
#24411972 - 06/17/17 06:53 AM (6 years, 8 months ago) |
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The "2300 m3/h Air Flow" number is what the filter was tested it at.
The resistance (static pressure) of your filter is 320Pa which = 1.284 "w.g. (a bit on the high side, you will need a powerful blower)
Your filter is 24"x24" so you want 400fpm of air flow, at the static pressure of your filter.
Every blower has it's own graph with a unique curve of resistance/cfm. You need to find one where the curve passes through (or slightly over) 400fpm / 1.3"w.g.
You can get a blower that is more powerful than needed. And get the right airflow by either choking off part of the intake, or using a motor speed controller.
This site has graphs for dayton brand blowers http://www.electricmotorwarehouse.com/squirrel-cage-blowers-1/
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blapporesto
Stranger


Registered: 10/24/16
Posts: 4
Last seen: 2 years, 3 months
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Re: Need help calculating correct blower type for my LFH [Re: foragedfungus]
#24412876 - 06/17/17 03:16 PM (6 years, 8 months ago) |
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So I found this blower on ebay, looks like it manages 680m3/h @ 370 Pa.
Does that look about right? Does it weird any of you out that it was manufactured in Turkey?
not sure if I'm kidding about the Turkey part...
but yea, I'll probably order this come Monday unless one of you wizards can convince me not to.
thanks for the advices
etc
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