Laminar Flow Hood

Nan's Nook : Archives : Gloveboxes : Laminar Flow Hood
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OT's Jar Tek  -    
420M's Flowhood -   420M
DirtyWOP's Flow Hood - 2/03 DirtyWOP
Flow Hood Math 5 6/03 montego
Engineering Handbook (zip file: flow hoods, fans, filters) 1 6/03 Fungusmaximus
Molester's 5 Minute Flow Hood - 2/03 Molester
Automotive Pre-filters 12 6/03 Mycota
HEPA Filter System  -  6/03  
Anno's Flow Hood - 3/03
Nan's Nook Flow Hood  -  2/03 Admin Team

By Nan (Nanook) on Friday, October 26, 2001 - 04:56 am:

Photo below, Da Hood.


Below, the blower box and controls. Note clasps.


Below, view of workspace.


Below, HEPA filter and workspace.


Below, Prefilters on top of blower box


Below, Prefilters removed, blower in box.


The two "big" items on your shopping list are the HEPA filter and the motor and blower. The filter is 24x24" and cost right around $300.00 with the shipping. The blower and motor were bought as a kit from Graingers and cost about $150.00 with the shipping. Buying them as a preassembled unit will double the cost. We used Catalog No. 7F735, a 1/5 HP motor and 9.5" squirrel cage blower with housing. In the future we'll probably find that a 1/2 HP motor will better serve us. Be aware that if you're going to use a rheostat to control the fan speed, your motor must be of the split capacitor type.

The casing is made entirely of 3/4" Malmar, which is a pre-covered plywood product.

We are using (3) 1x26x16 fiberglass filters stacked on top of each other as pre-filters. These are used to filter dust and other particulates, saving the HEPA filter for filtering bacteria and fungal spores.

There are two lights in the top of the work area. One is a cool white florescent, the other an Ultra Violet to sterilize the work area before use. The unit has a Malmar cover over the work area to prevent dust from entering as well as to prevent UV radiation from leaking into the room. The cover has two pegs set into the inside edge which match holes on the rim of the workspace. The cover is simply pulled off or pushed on.

The unit is rather large, and though it was built elsewhere, it had to be disassembled and reassembled in the way would it fit in the door.

The unit casing consists of 2 pieces, a base which contains an air chamber, the filter and the workspace, and the blower-box. The base has a dimension of 41" long x 29.5" wide x 25.5" high. If you note in the first picture below, the front is cut at an angle at the workspace. The length of the unit along the short line is 34.5".

The blower box is 21" long x 29.5" wide x 18.5" high and contains the blower and motor unit as well as a "tray" built into the top for the prefilters.

The actual workspace where work is done is 28" wide x 24" deep. The HEPA filter is just beyond a divider between the workspace and the air chamber. In essence, air is pulled down thru the prefilters in the top of the blower box, forced down into the air chamber below, thru the HEPA filter,and into the workspace.

Lastly, the electronics: Two toggle switches (One for each light) and one rheostat to control the speed of the fan. Appropriately, the white switch is for white light, the black switch is for UV.

The good Dr's Pressure Box : Nan's Partial Pressure Box : Gloveboxes : Shroom Glossary

By Brettiejams (Brettiejams) on Saturday, December 29, 2001 - 11:00 am:

O.K. fellow Nookians.....

I'm gonna build this hood, This Flow hood, in particular.

Now maybee I'm just lame....

but I cannot seem to indentify the part # ect. for the motor I need to order to build the hood depicted, from Grainger, the link supplied.

A little help, maybee?

Many thanks.


By An guy (Boomer) on Saturday, December 29, 2001 - 06:25 pm:

it's a squirrel cage blower.

I'll see if I can find a likely one, but my catalogue is 98-99.

looks like they're starting on page 3571, that looks abouit like a 4C006 or a 4C446. I would try the 006 myself, about $60.00 by now probably.

Here it is.

This page shows cfm of their different blowers. that 006 uses too much in the way of amps for my comfort, I'm thinking, after looking, and I can't find a cfm listing for it. I would guess you don't want huge air flow, you'd be blowing shit all over. well, I can't get that second link to work- go to grainger, HVAC, blowers, small centrifugal blowers- it's a listing of all their blowers in that category.

someone's probably beaten me by now with the exact model....;)

By Brettiejams (Brettiejams) on Saturday, December 29, 2001 - 06:38 pm:

Many thanks.... Boomer.

You are, indeed, a prince.

By An guy (Boomer) on Saturday, December 29, 2001 - 08:43 pm:

You're welcome, but man, I might be really wrong- the tec specifies at least 495cfm and .8" sp, that's kind of huge, and lots huger than the one I linked to above.

I wonder if that's right? Maybe there's a decimal missing? seems like that'd be a hurricane...I don't have much hepa experience though, maybe the filter will slow it down enough, but then you would think ....aahhh, shit, I don't know. I know you don't need a lot of air movement from the flowhoods they had where I used to work and that it gets more efficient if you put sides and a top to the front of it.

best to ya.

By Fishy1 (Fishy1) on Sunday, December 30, 2001 - 12:30 am:

Yea, try part # 4c448 at 465 cfm or #4c445 at 495 cfm. You need a big blower, as the filter will slow it down alot. fishy1
---its about 115 bucks.

By Fishy1 (Fishy1) on Sunday, December 30, 2001 - 12:36 am:

...or check ebay for a furnace blower...

By Grantshady (Grantshady) on Friday, May 04, 2001 - 02:44 am: Edit

Would it be overkill to get an air filter for the work area that will be used for the preparation of everything?

By Quote (Quote) on Friday, May 04, 2001 - 02:46 am: Edit

only you can decide that. it can't hurt, might help, if you got the $$, sure, why not ?

By Rokarij (Rokarij) on Friday, May 04, 2001 - 04:27 am: Edit

If you have the money, a really good way to go is to purchase:

very large aquarium - 50 gallons
12 x 12 x 5.8 inches HEPA filter (item # MF1212)
Tarzan fan (item # FAN350)

(item numbers from

Since I think most aquariums are almost precisely 12 inches wide, the filter will fit very snuggly into the aquarium. Install it so that it dissects the aquarium length-wise and silicone the edges on both sides very well. Then, cut a thick piece of plywood so that it fills the remaining gap (the aquarium should be taller than 12 inches ...).

Next step - cut a piece of plywood so that it totally seals off one half of the aquarium that you have just divided into 2 sections. The big aquariums typically come with black plastic railing to hold the glass together. You may have to play some tricks with melting sections of this away in order to get your filter in there, btw (use an old soldering iron). Before siliconing in this 2nd piece of plywood, cut a circular hole into the plywood for the fan (which can reside inside). Screw and/or silicone the fan to the wood and then silicone the wood to the aquarium - inside of the black plastic railing. You might want to consider glueing a metal screen to the outside of the wooden circle so that nobody cuts their fingers off from the high-speed fan.

The resulting positive airflow system is very trick and although it is expensive to make (about $400), it's extremely sturdy and less expensive than Stamets' pre-fabbed units. The airflow will be sufficient to perform sterile work and the best part is that if placed on its side, the aquarium glass acts as a shield to block hair and skin particles from hitting your work.

It also fits snuggly into most closet dimensions ...

By Fishy1 (Fishy1) on Friday, May 04, 2001 - 04:44 am: Edit

Anyone ever try an Ozone Generator? About 450 bucks here...just curious. The air filter construction sounds good to me. fishy1

By Brettiejams (Brettiejams) on Sunday, December 30, 2001 - 01:56 am:

Cool fishy.... I really appreciate the help guys.

By ion ewe (Ion) on Monday, December 31, 2001 - 11:21 am:

You could just make a glove box with a smaller blower if cost is a problem. Cost my buddy about $70 to build a replica of a $3000 piece of lab equipment...


By Imok Urok2 (Imok) on Monday, December 31, 2001 - 01:03 pm:

I was thinking along the same line ion.
In my way of thinking, you could combine a glove box with a flow hood.
On the glove box use saran-wrap for your view and hand(with a slit) ports.
Use big/long plastic cups(or pvc pipe) to connect the back of the
glove box to a plenium(empty box) that has a fan in a box above
blowing down into the plenium thru a hole.
On top of the fan box would be a filter box with vacum bag hepa filters
sticking inside and held in place by plastic cups filled
with poli-fil or paper towels wadded up inside.
The filter box would be connected to the fan box by either a hole,
several slits or one or more tubes connecting them together.
The whole thing could be taken apart and stacked inside of each other.
Sorry to take you OT Brettie

By quote: (Quote) on Monday, December 31, 2001 - 02:31 pm:

funny you should mention that, imok.
i just added a glovebox to my store-bought flowhood [$500} to improve its' performance.
i guess great minds think alike.

By An guy (Boomer) on Monday, December 31, 2001 - 08:10 pm:

You can take one or two box fans from the grainger catalogue, mount them on a piece of plywood, go get two dryer hose set ups, they come with several feet of hose and a mounting plate, the ones built so you can vent your dryer indoors?

mount that plate opposite side of the fans- holes cut in the plywood so the fans are blowing through it, into the hoses, the hoses have several inches of polyfil in them, they feed a box similar to that mentioned above- a small diameter pvc frame, just made of straight pipes and 90 elbows. viscuene around that, saran, plexi, whatever on the top, slits cut for hoses and your arms.

frame comes all apart, hoses squish down except where the polyfil is.

worked ok so far, still testing.

Fresh spores work shit better than old scrapings, I can say that.

That reminds me...