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OfflineNael
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Registered: 11/29/11
Posts: 20
Last seen: 9 years, 1 month
Need help building a laminar flow hood. * 1
    #17575411 - 01/19/13 08:01 PM (11 years, 3 months ago)

I have spent the past couple days looking around for a HEPA filter and fan so I can build a laminar flow hood. I know it isn't always the best idea to go for the cheapest you can find but that is exactly what I am doing. I can't afford to spend more than $250 for the filter and fan combined. I have only really found one filter that is 6 inches wide in the price range I need. I found 12 inch ones but my understanding is that these provide to much resistance and are not the best at creating laminar flow.

Here is the filter I found:

http://www.norkan.com/Norkan_Store/index.php?main_page=product_info&products_id=344


http://www.ebay.com/itm/4th-Stage-24-x-16-HEPA-Filter-Aerospace-America-/370267114277?pt=LH_DefaultDomain_0&hash=item5635a3cb25

By my calculations I only need a fan rated at 266.66 CFM. 1.33 * 2 * 100.

However I figured I should get one rated for at least 400 CFM.

I would like to use these in-line style centrifugal squirrel fans. I've seen some people hating on the in-line models. Why is this?

Here are the in-lines I'm looking at:

http://www.ebay.com/itm/HO-400CFM-Ventilation-6-Inch-Inline-Cooling-Duct-Fan-Exhaust-Air-Blower-Vent-/160679252910?pt=LH_DefaultDomain_0&hash=item25693ad3ae

http://www.ebay.com/itm/6-Inline-Hydroponic-Ventilation-Fan-Air-Blower-400-CFM-2890-RPM-110v-/121009867810?pt=LH_DefaultDomain_0&hash=item1c2cc00c22

and here is the slightly more expensive squirrel style 465 CFM fan I'm looking at:

http://www.amazon.com/Active-Air-Blower-System-465/dp/B004K65JZG/ref=pd_sim_sbs_hg_2

I would like to get the in-line style and the filter posted but I'm not 100% that I know what I am doing and since I'm going for cheap I don't want to make the mistake of sacrificing too much quality for savings.

Suggestions and advice appreciated. If anyone knows of any available  parts that are even cheaper and just as good please let me know!

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OfflineNael
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Registered: 11/29/11
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Last seen: 9 years, 1 month
Update: [Re: Nael] * 1
    #17581460 - 01/20/13 08:13 PM (11 years, 3 months ago)

I've been recommended this filter:

http://www.ebay.com/itm/271060646577?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

and this fan:

http://www.plantlightinghydroponics.com/hurricane%C3%82%E2%84%A2-inch-inline-fan-745-cfm-p-3803.html

Am I wrong about 12" deep fans having too much resistance? Will I be able to achieve a proper 100 CFM laminar flow with these two components?

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OfflineNael
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Registered: 11/29/11
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Last seen: 9 years, 1 month
Re: Update: [Re: Nael] * 1
    #17584697 - 01/21/13 12:14 PM (11 years, 3 months ago)

Anybody ?

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Offlinet3chnobily
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Re: Update: [Re: Nael]
    #17587052 - 01/21/13 07:42 PM (11 years, 3 months ago)

Thicker filters just take up more room.  That filter should be fine with .9 IN WG.  Check this out for sizing the fan. http://www.fungifun.org/English/Flowhood

Keep at it.  Just fired up my homemade hood today for the first time!

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OfflineNael
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Registered: 11/29/11
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Last seen: 9 years, 1 month
Re: Update: [Re: t3chnobily] * 1
    #17587266 - 01/21/13 08:22 PM (11 years, 3 months ago)

Quote:

t3chnobily said:
That filter should be fine with .9 IN WG.





I realize that WG is water gauge and each filter has a different static pressure at the ideal laminar flow point but I don't really understand  what you mean by .9 IN WG. Nor do I understand the listings ratings on the filter (most recently linked one):

"PENETRATION 006% DOP @ 20% 009%"

Is this where you are deriving the .9 IN WG from? I don't see those units being used.

Does anybody advise against 12" deep filters? I believe I've read RR saying that they are not suited for microbiological applications.

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OfflineDR.D
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Re: Update: [Re: Nael]
    #17590248 - 01/22/13 01:04 PM (11 years, 3 months ago)

I might invest in the same setup if more feedback from experienced users agree with the products?!

-DR

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Offlinet3chnobily
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Re: Update: [Re: DR.D]
    #17592203 - 01/22/13 06:34 PM (11 years, 3 months ago)

says .9  IN WG right on the filter which means it has enough resistance to create laminar flow.  Penetration and DOP (degree of penetration?) at full flow (1000cfm) and 20% (200 cfm) refers to the size particle that makes it through the filter during testing.  In microns I believe.  This filter will work for mycology with the proper set up and fan.

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OfflineNael
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Registered: 11/29/11
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Last seen: 9 years, 1 month
Re: Update: [Re: t3chnobily]
    #17592878 - 01/22/13 08:23 PM (11 years, 3 months ago)

It looks like that value is .4 to me not .9. Would that still be okay?

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OfflineRogerRabbitM
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Re: Update: [Re: Nael]
    #17595001 - 01/23/13 05:10 AM (11 years, 3 months ago)

Quote:

Nael said:
I've been recommended this filter:

http://www.ebay.com/itm/271060646577?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

and this fan:

http://www.plantlightinghydroponics.com/hurricane%C3%82%E2%84%A2-inch-inline-fan-745-cfm-p-3803.html

Am I wrong about 12" deep fans having too much resistance? Will I be able to achieve a proper 100 CFM laminar flow with these two components?




First things first:  You don't want a fan, period.  You want a blower.  The difference is a fan will cavitate when confronted with the task of building static pressure, while a blower is actually designed to do so.

That 12" filter has no pictures of the data tag, and the gibberish they wrote in the description doesn't make sense, so there's no way to determine blower size.

12" filters generally have less resistance than thinner ones.  This makes it easier to achieve laminar flow with thinner filters because it's important to have a steady static pressure in the plenum.
RR


--------------------
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semper in excretia sumus solim profundum variat

"I've never had a failed experiment.  I've only discovered 10,000 methods which do not work."
Thomas Edison

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OfflineNael
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Registered: 11/29/11
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Last seen: 9 years, 1 month
Re: Update: [Re: RogerRabbit]
    #17596445 - 01/23/13 01:15 PM (11 years, 3 months ago)

Quote:

RogerRabbit said:
Quote:

Nael said:
I've been recommended this filter:

http://www.ebay.com/itm/271060646577?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

and this fan:

http://www.plantlightinghydroponics.com/hurricane%C3%82%E2%84%A2-inch-inline-fan-745-cfm-p-3803.html

Am I wrong about 12" deep fans having too much resistance? Will I be able to achieve a proper 100 CFM laminar flow with these two components?




First things first:  You don't want a fan, period.  You want a blower.  The difference is a fan will cavitate when confronted with the task of building static pressure, while a blower is actually designed to do so.

That 12" filter has no pictures of the data tag, and the gibberish they wrote in the description doesn't make sense, so there's no way to determine blower size.

12" filters generally have less resistance than thinner ones.  This makes it easier to achieve laminar flow with thinner filters because it's important to have a steady static pressure in the plenum.
RR




I intuitively assume that there is more material for the air to pass through in a 12" filter as opposed to a 6" one. So why is it that  thinner filters generally have more resistance? Are they generally made with tighter woven layers ?

Would this blower work with either of these filters? I would much prefer using the 24X24 as I feel 16" of height would be too short for bag transfers.

Fan:

http://www.amazon.com/Active-Air-Blower-System-465/dp/B004K65JZG/ref=pd_sim_sbs_hg_2

Filters:

http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=160695413329&item=160695413329

http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=170797809955&item=170797809955

Edited by Nael (01/24/13 05:59 PM)

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OfflineDR.D
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Registered: 03/30/12
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Re: Update: [Re: Nael]
    #17604363 - 01/24/13 06:07 PM (11 years, 3 months ago)

One would tend to think that the thicker filter would have more resistance.. hmm..

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Invisiblelipa

Registered: 07/24/07
Posts: 2,684
Trusted Cultivator
Re: Update: [Re: DR.D]
    #17608128 - 01/25/13 10:44 AM (11 years, 3 months ago)

There is more surface area on the filter material on a 12 inch filter thus more air is let through. Less resistance.

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OfflineNael
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Registered: 11/29/11
Posts: 20
Last seen: 9 years, 1 month
Re: Update: [Re: lipa]
    #17610686 - 01/25/13 06:58 PM (11 years, 3 months ago)

Quote:

lipa said:
There is more surface area on the filter material on a 12 inch filter thus more air is let through. Less resistance.




I do not believe the depth of the filter contributes to the surface area. The face is 2 feet by 2 feet regardless of the depth. This is the area exposed to the pressurized plenum/flow of air. You take into consideration only the height and width of the filter when calculating necessary CFM; according to the various guides and The Mushroom Cultivator by Stamets.

If I were to walk through a patch of dense woods/shrubs 6' feet in length, I would be subject to less friction and thus less resistance than if I were to walk through one 12' feet in length, assuming they were of uniform density. Is air not effected in the same way? Why would a longer path (12") of like-material have less resistance than a shorter one (6"). Deeper the layer = the more friction and filtering a unit of air must undergo = more resistance to the pressure (unless 6" filter are woven tighter).

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OfflineRogerRabbitM
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Re: Update: [Re: Nael]
    #17611606 - 01/25/13 10:34 PM (11 years, 3 months ago)

Simply look at the specs.  Most 12" thick filters have a lower resistance than the 5" thick filters. It's counter-intuitive, but simply the way they're made tighter, and not because of drag or wetted area.

You don't calculate for the blower based on depth of filter, but on the cubic feet per minute which must pass at a given resistance.
RR


--------------------
Download Let's Grow Mushrooms



semper in excretia sumus solim profundum variat

"I've never had a failed experiment.  I've only discovered 10,000 methods which do not work."
Thomas Edison

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Invisiblelipa

Registered: 07/24/07
Posts: 2,684
Trusted Cultivator
Re: Update: [Re: Nael]
    #17613791 - 01/26/13 12:37 PM (11 years, 3 months ago)

Quote:

Nael said:
Quote:

lipa said:
There is more surface area on the filter material on a 12 inch filter thus more air is let through. Less resistance.




I do not believe the depth of the filter contributes to the surface area. The face is 2 feet by 2 feet regardless of the depth. This is the area exposed to the pressurized plenum/flow of air. You take into consideration only the height and width of the filter when calculating necessary CFM; according to the various guides and The Mushroom Cultivator by Stamets.

If I were to walk through a patch of dense woods/shrubs 6' feet in length, I would be subject to less friction and thus less resistance than if I were to walk through one 12' feet in length, assuming they were of uniform density. Is air not effected in the same way? Why would a longer path (12") of like-material have less resistance than a shorter one (6"). Deeper the layer = the more friction and filtering a unit of air must undergo = more resistance to the pressure (unless 6" filter are woven tighter).




So are you trying to say if you blow through a 1/8 inch hole there is less resistance than if you blew through a 1/4 inch hole?

The filter material is folded the entire length of the 12 inches. There is a lot more passage than a 6 inch for the air only. These 12inch filters are not called high volume filters for nothing. It's made of the same material as the 6inch. The filters with the metal corrugation between help to create laminar flow as long as the flow is within a certain range. However these filters suck because everytime you touch the metal on accident it pokes a hole in the rear of the pleat and lets particulates through. These filters don't work well with anything in front of them to protect the filter from you damaging it. The best setup is those filters without the metal and walls all around to help direct the flow towards you. These filters are the nice ones. I encourage you to read the description.

FYI to everyone just for your info. Every hepa filter when made is made to the same specs. When they are tested the ones that get labeled 98% or 97% or 99.97 are the ones that don't pass for the 99.999% filters. They all come from the same assembly line with the same filter material. They are labeled by there performance when tested.

Lipa

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