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FYI: a hepa filter alone does not provide laminar flow.


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#1 Athanasius

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Posted 28 March 2019 - 01:35 PM

I've read quite a few DIY posts about laminar flow hoods that didn't include the portion that looks like a honey comb or a bunch of straws stacked together.   I questioned it because I have and understanding of laminar flow being flow that is unidirectional without turbulence and it's not possible to get that without tubes to "straighten" the air out. 

I'm pretty green to mycology and am focused primarily on gourmet mushrooms but I thought since I need to post anyway perhaps this will help another new mycologist. 

 

Ath


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#2 MiltonWadams

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Posted 29 March 2019 - 09:14 PM

Just curious, what is the importance of laminar flow to a grow? If you're trying to cool or provide a consistent humidity, turbulent flow is preferable.

It's possible to have laminar flow without the honeycomb, it just depends on how you're moving the air. Fans produce a ton of turbulence, so the honeycomb is used to smooth the flow right before a test of aerodynamics, for example, but you're right, a HEPA filter won't create laminar flow by itself.



#3 Cuboid

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Posted 30 March 2019 - 03:27 AM

In this context it's a laminar flow hood for clean working. The area directly in front of the HEPA filter (typically 12" x 24" for us cheapo amateurs but much bigger for professional labs) is free from airborne contamination. If the flow out the filter is turbulent it will pull dirty air into that work area.
Haven't had coffee yet so that's the best succinct explanation I can manage just now.
Perhaps goggle 'mycology laboratory flow hood' and/or related terms.
HTH,
Cuboid.

#4 Ocitown

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Posted 30 March 2019 - 08:06 PM

In this context it's a laminar flow hood for clean working. The area directly in front of the HEPA filter (typically 12" x 24" for us cheapo amateurs but much bigger for professional labs) is free from airborne contamination. If the flow out the filter is turbulent it will pull dirty air into that work area.
Haven't had coffee yet so that's the best succinct explanation I can manage just now.
Perhaps goggle 'mycology laboratory flow hood' and/or related terms.
HTH,
Cuboid.

Has there been a tech to build a HEPA glovebox that would be a cheaper version on a diy scale?
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#5 bezevo

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Posted 30 March 2019 - 08:36 PM

most no longer make glove box  , the make whats called a SAB....STILL AIR BOX  . its a medium to large clear tote . you place upside down on your clean/sanitized work area with two  simple arm holes cut out or melted out with like a hot tomato juice  can ...................think about how  you do that long and hard so your not burning your fingers  or breathing toxic melted plastic fumes ................easy

clean work room , take shower , clean clothing ,right out of dryer ,

practic slow moves in SAB so  not stirring up air .

please please don't be spritzing flammable Lysol or alcohol near open flame or in your SAB 

 

BOOM FIRE BALL


Edited by bezevo, 30 March 2019 - 08:41 PM.


#6 Ocitown

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Posted 31 March 2019 - 11:45 AM

most no longer make glove box  , the make whats called a SAB....STILL AIR BOX  . its a medium to large clear tote . you place upside down on your clean/sanitized work area with two  simple arm holes cut out or melted out with like a hot tomato juice  can ...................think about how  you do that long and hard so your not burning your fingers  or breathing toxic melted plastic fumes ................easy
clean work room , take shower , clean clothing ,right out of dryer ,
practic slow moves in SAB so  not stirring up air .
please please don't be spritzing flammable Lysol or alcohol near open flame or in your SAB 
 
BOOM FIRE BALL

Cool beans,thanx.

Seems a GB and a SAB are the same thing,the GB pix I see have only holes no actual gloves =SAB?

#7 sandman

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Posted 31 March 2019 - 01:30 PM

No commercial flow hoods have any kind of "honey comb to straighten the air out" because is totally unnecessary. The laminar flow is achieved by having an even pressurized plenum of air behind the filter and the air velocity between about 85 and 110 feet per minute.


Edited by sandman, 31 March 2019 - 01:32 PM.


#8 DaveyJonez

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Posted 02 April 2019 - 07:04 AM

In this context it's a laminar flow hood for clean working. The area directly in front of the HEPA filter (typically 12" x 24" for us cheapo amateurs but much bigger for professional labs) is free from airborne contamination. If the flow out the filter is turbulent it will pull dirty air into that work area.
Haven't had coffee yet so that's the best succinct explanation I can manage just now.
Perhaps goggle 'mycology laboratory flow hood' and/or related terms.
HTH,
Cuboid.

Has there been a tech to build a HEPA glovebox that would be a cheaper version on a diy scale?
Yes, I can't remember where I saw it but some guy did a positive pressure clear trash bag with a hepa.. I took his idea and I used a dremel to cut a rectangle out of the back of my SAB and stuffed the blowing end of the hepa filter in there then I spray with fungicidal/antibacterial, close the lid, and turn it on.. Then I just make sure I wipe down with alcohol Everytime I put my hands in and out.




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