33 replies to this topic

[sandman]

Flowhoods - the holy grail of our hobby. They allow you to do sterile work without any worry of contammination when used properly. Basicaly a flowhood consists of a blower motor (squirel cage blower) and a big assed HEPA filter. They are mated in such a way that you work directly in front of the filters face under a constant laminar stream of filtered air.

***Required for building my flowhood***
Electric Drill with big drillbit for starting compound cuts
Jigsaw for making compound cuts
Loctite Power Grab (I used about 2.5 tubes)
Silicone Caulking
Caulk Gun
Killz 2 Primer/Sealer and paintbrush
Automotive filter for Prefilter
HEPA Filter
Squirell Cage blower

First things first....decide how much work space you need. I opted for the ginormous 2'x4'x6" 99.999% HEPA. I think most would find a 1'x2'x6" or 2'x2'x6" filter more suitable since this thing takes a lot of space up. Make sure you get at least a 99.99% filter. Regular filters for normal hepa filter machines that are available at WalMart or whatever will NOT WORK for this purpose. You need the real deal 6" thick 99.99+% filters made for this application. Try ebay, or search arround. Perhaps ome sponsers here sell the filters. Expect to pay $100+ for the filter.

OK then, now you need a squirell cage blower. You will need a blower that produces adequate cfm at the pressure your filter creates. There are some flowhood math involved....I didnt really do any here, cause I basically matched what fungi.com calls there Series IV hood it ays it is a 2'x4' filter with a 1/3 hp blower motor, so thats what I got. My blower is rated at 1200cfm. I would imagine that a 500-800 cfm blower would be sufficient for a smaller filter like the 2'x2'.

I constructed my hood with no nails, no screws and hardly any brain cells. All that you are doing is building a box arround a filter, then a box on top of that to house the blower and prefilter. 2 boxes. Real easy. Especially when your just using Loctite Power Grab construction glue/caulk stuff for putting it together.

You will need to draw up some plans after you get your filter and blower delivered since they will all be variable in exact size. Dont worry though its easy once you check out this teks pictures you will get the idea.

The dood at lowes or whatever will cut your dimensions for free! Except for the hole for the prefilter and the slanted sides and the hole for the blower input on the top panel, since it is a compound cut you will have to make these yourself which will require a drill and a jigsaw. The whole thing is nothing more than a bottom panel, 2 side panels, back panel, top panel, and the 5 panels for the smaller prefilter box. 10 peices...make sure you concider the width of the lumber your uising and how it will fit together so your shit comes together right. Thats why i used 1/2" lumber cause its easy to calculate how the peices fit together.

Ok so to begin construction....Lay your bottom panel out, mark where your filter will lay, and apply a good ammount of Power Grab where the filter will go. Lay the filter on the bead of glue and press down. Look your almost done! JK but not really. Now lay a bead where the side panels will go. All over the side of the filter and everything. Lay on the sides. Repeat for the top panel. Now on the inside before you put the back on, lay a bead of silicone allong the edges of all the joints and allong the filter so it is airtight in there. Then lay your glue for the back panel and apply. At this point your hood is basicaly constructed.

Now grab your blower and lay it on a bead of glue over your hole on the top panel for blower input. Get it nice and sealed up with more caulk or duct tape if you have to. Now lay the panels for the box that goes arround the blower with more Power Grab glue. Insert and glue your prefilter to the top panel of the prefilter box, then glue that panel to the top over you blower and general construction is complete!

All you need to do now is to paint the work area and all of it if you want with some Killz 2 primer/sealer. 2 layers of paint here so you can wipe alcohol all over the place all day long.

Pretty much that it...your done. Test her out....feel the breeze!

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[Hippie3]

lookin' good

[Lazlo]

Do doubt! Nice job and fairly simple to construct. How much money do you have into it?

[sandman]

$325 grand total. Not bad since the stage IV is over $1500 at fungi.com! Any idiot could build it with this method (I did!). Basicaly you just put some glue down and lay some panels arround the filter...As long as you measured everything right it should just plop together.

[sandman]

I am letting the silicone dry up then I will do some g2g's with large filter patch bags in the morning...The big test. I will take some more pics as well as make some sketches of the design basics for anyone looking into building one.

[Strawgiant]

what are the benifits of something like this over a cheaper glove box?

[saskashroom]

man thats way cool!!!:hitit:

[python]

how is the "laminar flow" looking........?

[sandman]

the benefits of a Flowhood over a GB:
You can take your time in a flowhood.
You can work ata normal pace (IE you dont have to move slooow)
Its easier to work in a hood and more natural
You can preform much larger projects inside of a flowhood at one time

The benefits of a GB over a flowhood:
You can work with contaminated cultures, to transfer to clean dishes. Cant do this in a flowhood cause it blows the contams everywhere....

[Strawgiant]

I see now,thnx much Sand,I may try something like this...im all about being comfortable:)

[boots420]

now thats a flowhood!!!!! sicc job there sandman. i'm going to be building myself one real soon.

[llamabox]

One of these days I will be cool too.

Good work Sandman.

[Hippie3]

i find the cool breeze from the flowhood to help
keep me from sweating as much, more comfortable for
working for long periods of time.

[Lazlo]

how is the "laminar flow" looking........?

I'm curious to know that myself. I see you chose not use anything for fan speed control. How's it looking?

[sandman]

Looking pretty fly!

A couple of updates....My prefilter was too restrictive, so I had to loosen the top to have a air gap which allowed me to fine tune the output. i will have to do something about filtering the air coming through the gap, but most of the air coming in is still going through the prefilter, you can really feel it sucking through.

I tried to take some prints ......lmao I just dried the caps up and got no prints! LOL should have thought that one through better and covered the caps with a fold in the foil or something.

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[Lazlo]

That looks perfect!

[python]

you dont need to take your prints in front of the hood.......

and even a tuft of polyfill could be used to fill the gap as you just want to pull some particles out of the air before it reaches the hepa

[waylitjim]

Nice work Sandman :bow:

The term Laminar Flow as it applies to hoods or clean air equipment can typically means air flowing in one direction (unidirectional) with very low turbulence. In a horizontal "Clean Bench" air flows straight out of the hood towards the operator.

Laminar Flow Hoods provide clean air to the working area. They provide a constant flow of air out of the work area to prevent room air from entering. The air flowing out from the hood suspends and removes contaminants introduced into the work area by personnel.

The most important part of a laminar flow hood is a high efficiency bacteria-retentive filter. Room air is taken into the unit and passed through a pre-filter to remove gross contaminants (lint, dust etc). The air is then compressed and channeled up behind and through the HEPA filter (High Efficiency Particulate Air filter) in a laminar flow fashion--that is the purified air flows out over the entire work surface in parallel lines at a uniform velocity. The HEPA filter removes nearly all of the bacteria from the air.

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[Lazlo]

I've seen a lot of pics where people use a/c return filters for pre-filtering a flow hood. That intake filter probably does put some drag on the blower.