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OfflineMetacanna
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Registered: 01/23/17
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Last seen: 1 year, 7 months
48" x 24" Flow hood match - Centrifugal blower + HEPA
    #24935705 - 01/23/18 11:19 AM (3 years, 3 months ago)

Hey,

I'm in the process of sourcing parts to build a 48"x 24" flow hood for a commercial operation yet to begin.

I got a quote from a German manufacturer for an HEPA 48"x 24", 6" deep, ask price 170€. Nominal airflow 1353CFM.

First I calculate the surface area of the filter, then I will try to match a blower.

48"x24" = 4ft x 2ft = surface area of 8ft squared.

Multiply the required air speed(100 ft/min) with the area of my filter.

100ft/min X 8ft squared = 800 ft cubed/min

So, in theory I would need a 800CFM blower to do the job. However, due to friction, turbulence and variable motor efficiency, the air speed will be less than the calculated. For that reason RR say we should aim for a blower able to deliver 20% more output.
This said, I will need a 950CFM blower.

The nominal airflow of the filter I choose is 1353CFM, at 950CFM the filter will be operating at 70%. The spreadsheet of this HEPA tells me at that rate the resistance is 0.6 W.G (150 Pascals).

In order to match the perfect blower I had to spend 400€. For half of that I found on ebay an industrial blower rated 1180CFM with a 5A speed controller included. The spreadsheet isn't available but it draws up to 430W, so it must be powerful enough to operate at 0.6 W.G and much more, it's a massive 20lbs of equipment, so it must work, right?


Any thoughts on the construction of a flow hood this size?


Some useful link I found during my research:

Made in Germany heavy duty, not that expensive blowers:

http://www.ebmpapst.us (with representation all over Europe)

Detailed instruction to build a flow hood using European metrics:

http://www.orchideenvermehrung.at/english/lfh/index.htm

German HEPA filters (you want HS-Mikro SF models):

https://www.luftfilterbau.de/en/products/productfinder/hepa-ulpa/index.html

More German HEPA filters (you want Hepatex CR-WS models)

https://airfiltration.mann-hummel.com/products/hepa-and-ulpa-air-filters/

EvilMushroom's Flowhood Build: https://www.shroomery.org/forums/showflat.php/Number/13851289

:fasted:



edit: links added


Edited by Metacanna (01/23/18 11:27 AM)


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Offline8_Gonzo_8
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Registered: 11/15/17
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Re: 48" x 24" Flow hood match - Centrifugal blower + HEPA [Re: Metacanna]
    #25040107 - 03/05/18 11:56 AM (3 years, 2 months ago)

Quote:

Metacanna said:
Hey,

I'm in the process of sourcing parts to build a 48"x 24" flow hood for a commercial operation yet to begin.

I got a quote from a German manufacturer for an HEPA 48"x 24", 6" deep, ask price 170€. Nominal airflow 1353CFM.

First I calculate the surface area of the filter, then I will try to match a blower.

48"x24" = 4ft x 2ft = surface area of 8ft squared.

Multiply the required air speed(100 ft/min) with the area of my filter.

100ft/min X 8ft squared = 800 ft cubed/min

So, in theory I would need a 800CFM blower to do the job. However, due to friction, turbulence and variable motor efficiency, the air speed will be less than the calculated. For that reason RR say we should aim for a blower able to deliver 20% more output.
This said, I will need a 950CFM blower.

The nominal airflow of the filter I choose is 1353CFM, at 950CFM the filter will be operating at 70%. The spreadsheet of this HEPA tells me at that rate the resistance is 0.6 W.G (150 Pascals).

In order to match the perfect blower I had to spend 400€. For half of that I found on ebay an industrial blower rated 1180CFM with a 5A speed controller included. The spreadsheet isn't available but it draws up to 430W, so it must be powerful enough to operate at 0.6 W.G and much more, it's a massive 20lbs of equipment, so it must work, right?


Any thoughts on the construction of a flow hood this size?


Some useful link I found during my research:

Made in Germany heavy duty, not that expensive blowers:

http://www.ebmpapst.us (with representation all over Europe)

Detailed instruction to build a flow hood using European metrics:

http://www.orchideenvermehrung.at/english/lfh/index.htm

German HEPA filters (you want HS-Mikro SF models):

https://www.luftfilterbau.de/en/products/productfinder/hepa-ulpa/index.html

More German HEPA filters (you want Hepatex CR-WS models)

https://airfiltration.mann-hummel.com/products/hepa-and-ulpa-air-filters/

EvilMushroom's Flowhood Build: https://www.shroomery.org/forums/showflat.php/Number/13851289

:fasted:



edit: links added




Did you finish your build?

I'm going to build the same size and looking at some of the same products you mentioned.

Would like to see see some pics and a summary of your build.


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OfflineMetacanna
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Registered: 01/23/17
Posts: 94
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Re: 48" x 24" Flow hood match - Centrifugal blower + HEPA [Re: 8_Gonzo_8]
    #25041378 - 03/05/18 09:18 PM (3 years, 2 months ago)

Hey. Only thing I have to show so far is the blower and a 5 amp (220V) controller. The HEPA filter arrives in three weeks, bought it from mann-hummel.

Hope to have some pictures in a month. 



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Offline8_Gonzo_8
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Re: 48" x 24" Flow hood match - Centrifugal blower + HEPA [Re: Metacanna]
    #25042282 - 03/06/18 09:27 AM (3 years, 2 months ago)

What hepa filter did you choose?


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OfflineMetacanna
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Registered: 01/23/17
Posts: 94
Last seen: 1 year, 7 months
Re: 48" x 24" Flow hood match - Centrifugal blower + HEPA [Re: 8_Gonzo_8]
    #25042377 - 03/06/18 10:44 AM (3 years, 2 months ago)

Mann-hummel Hepatex CR-WS 1220mm x 610mm, 150mm depth, H14 rating = 99,995%. You can find the spreadsheet on their website. Their site is down right now... Try later.


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Offline8_Gonzo_8
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Registered: 11/15/17
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Re: 48" x 24" Flow hood match - Centrifugal blower + HEPA [Re: Metacanna]
    #25042550 - 03/06/18 12:05 PM (3 years, 2 months ago)

I'm thinking of getting the HEPATEX-CR it has a aluminium outer,the CR-WS is a MDF wood outer. Both seems to be used for laminar applications.

Your blower is 1950 m3/h (1147cfm)
1cfm = 1.7 m3/h

Do you have the spec sheet of that blower?

The hepa filter specsheet doesn't give much but it looks like it is 250pa? and with the added prefilter you will have 300PA

Does your blower deliver 800cfm at 300PA?

I was looking today at blowers and found that a 1800 cfm blower could not even do 800cfm at 175PA (0.7")

So i looked at a bigger one 2160 cfm could do 850 cfm at 175PA

(Please note-The 175 PA was for a different hepa filter than the CR models)
Hence why i mention the 175 PA


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OfflineMetacanna
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Registered: 01/23/17
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Re: 48" x 24" Flow hood match - Centrifugal blower + HEPA [Re: 8_Gonzo_8]
    #25044636 - 03/07/18 08:54 AM (3 years, 2 months ago)

The aluminium frame increases the price, not sure if its worth the extra you paying for that.

The blower didn't come with any specs but I'm assuming I can compare it to this one, has the same dimensions, height, rated airflow and power consumption: http://www.ebmpapst.us/en/products/centrifugal_fans/forward_curved/dual_inlet/dual_inlet_detail.php?pID=109

Check the graph on that one.

250pa is the nominal value used to test the HEPA filter and create those spreadsheets, however you don't need to run the filter at 250pa to achieve laminar flow.

On this spreadsheet you can see how the pressure drop [Pa] is correlated to the air flow passing through the filter.
For instance take the dimensions 1220 x 610, the nominal airflow for that one is 2300 m3/h, the manufacture call it the "standard value".
If you run it lower than the "standard value" than the pressure drop [Pa] is lower as well.

https://www.luftfilterbau.de/cms/upload/2012/en-data/EN-07-D02-HS-Mikro%20SF.pdf


In the end it's hard to have all the answers to every aspects of the build. Many folks here have ordered a random HEPA filter from ebay, adapted an old unrated blower they had around and they ended with cheap flow hood that works for them. Proof that common sense works, even for mycology. :grin:


Edited by Metacanna (03/07/18 09:00 AM)


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Offline8_Gonzo_8
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Re: 48" x 24" Flow hood match - Centrifugal blower + HEPA [Re: Metacanna]
    #25045201 - 03/07/18 12:17 PM (3 years, 1 month ago)

I was told it was the cheaper one from the one you are getting,i will get a official price from my supplier to see if he is not lying,maybe your one is cheaper lol

I found your flowchart for that blower. I cant understand the PA on that chart it seems to be wrong(HIGHER than usual,different measure)?

And are you sure your blower shouldn't deliver 800cfm @ 300PA(The PA of your Hepa+prefilter) 

Here is a link to explain it all
http://www.fungifun.org/English/Flowhood




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OfflineMetacanna
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Re: 48" x 24" Flow hood match - Centrifugal blower + HEPA [Re: 8_Gonzo_8]
    #25047924 - 03/08/18 08:07 AM (3 years, 1 month ago)

Weird, I didn't even ask for a quote I simply assumed the aluminium frame would increase the price.

Could you post the link for the graph? I didn't find it on the manufacture website. 
Indeed, the pressure drop on that graph doesn't sound right.

From the link you posted:

Quote:

Every filter has a "resistance" when air blows through it at a certain speed, this resistance is called the "static pressure".

Press your hand against your mouth. Now try to blow through it. Dependant on how firm you press it against your mouth, you will have some difficulties blowing air out and you will feel some resistance, this is the static pressure.

Every filter has a different static pressure at the working point. The working point is where the amount of the air flowing through the filter is sufficient to meet the requirement of the laminar flow.




What I said:

Quote:

For instance take the dimensions 1220 x 610, the nominal airflow for that one is 2300 m3/h, the manufacture call it the "standard value".




Based on the calculations on my first post I need to move air trough the HEPA at rate of 950 CFM (1600 m3/h).



So, if I need to move 950 CFM (1600 m3/h) and the nominal value of the filter I chose is 2300 m3/h (at 250Pa), then I need to run at only 70%. The pressure drop at that air flow is around 170Pa.


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Offline8_Gonzo_8
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Re: 48" x 24" Flow hood match - Centrifugal blower + HEPA [Re: Metacanna]
    #25047956 - 03/08/18 08:42 AM (3 years, 1 month ago)

Did you not order from mann hummel? You are posting a link to a different place and filter. Here is the link for your filter,CR-WS?
https://airfiltration.mann-hummel.com/fileadmin/user_upload/products/EPA_HEPA_ULPA%20Filters/Hepatex_CR_WS/Hepatex_CR-WS_EN.pdf

I  believe it is 2150m3/h @ 250PA for your filter according to that link ? It's best to ask the supplier always to send the individual charts.

So you need a blower pushing 800cfm @ 250PA(+50Pa for your prefilter) which makes it 300PA @ 800cfm.

Basically you can have a blower pushing 1300 cfm and it might not reach 800cfm @ 300PA,because each blower works differently when it has resitence (PA) hence why it's important to get the chart of the blower.

THe blower needs to match that more or less exactly,you could try and email them,the email is on your blower and ask to send the chart for you then you will know for sure.

But as you said some people just rig up and go without too much precise calculations,i believe your blower will be correct,it might be a little strong,then you can just add another prefilter perhaps.

I think i'm making it more complicated then it should be haha i'm just following what stamets recommends,i might not even be right?


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OfflineMetacanna
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Re: 48" x 24" Flow hood match - Centrifugal blower + HEPA [Re: 8_Gonzo_8]
    #25047986 - 03/08/18 09:14 AM (3 years, 1 month ago)

Yes, I ordered from mann+hummel but I'm posting the spreadsheet of a similar filter from luftfilterbau because these have more information, which I found useful to post here so you could see how pressure drop and airflow are related.

Quote:

Basically you can have a blower pushing 1300 cfm and it might not reach 800cfm @ 300PA,because each blower works differently when it has resitence (PA) hence why it's important to get the chart of the blower.




As you can see on the graph I posted in my last reply, at 800CFM (1300 m3/h) the filter is running lower than 250Pa. 2300 m3/h is the nominal value (100%) which correspond to 250Pa, if you run it slower the pressure is lower.
You can take that info and extrapolate it to the mann+hummel HEPA filters.

Regarding the blower specs I'm using common sense here. It's a massive piece of equipment for the task, it must work.


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Offlinetomithecat
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Re: 48" x 24" Flow hood match - Centrifugal blower + HEPA [Re: Metacanna]
    #25054792 - 03/10/18 05:41 PM (3 years, 1 month ago)

hey

great post. thanks you for all the information.
doing my research this days, finally time to get myself a flowhood.
i found the numbers and calculations really hard :/


Ill probably go for the  Hepatex CR-WS  48x24 H14 aswell.

i got lost a bit with selecting the blower - will this one do the job ?

http://www.ebmpapst.us/en/products/centrifugal_fans/forward_curved/dual_inlet/dual_inlet_detail.php?pID=109


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Offline8_Gonzo_8
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Re: 48" x 24" Flow hood match - Centrifugal blower + HEPA [Re: Metacanna]
    #25192918 - 05/09/18 07:15 AM (2 years, 11 months ago)

Any update on your flowhood?


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