# Cabinet for Fume Hood



## Profikiskery (Feb 15, 2015)

Was thinking about building a fume hood until I ran across this in my basement. Its a bass cabinet that was in my teenage sons' car. 38x28x20 inches.

Thinking I can knock that board in the middle out and line it with rhino liner or black rubber water sealant. Was thinking about leaving the big holes just like they are and covering them. Cutting a standard square opening is also an option, but I was thinking I might lost the lip on the bottom if I did that and that would be nice to keep for spills. 

If anyone has any ideas or suggestions to add before I get started I could use your experiences. This just seems like it will be ideal and will save me the cost of materials.


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## kurtak (Feb 16, 2015)

Anything metal would need a chem resistant coating both inside & out

Here is a good thread to read on fume hoods & scrubbers :arrow: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=40&t=19965 (I may have posted this for you the other day - if not it a good read)

Kurt


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## justinhcase (Feb 16, 2015)

M.D.F. will swell and turn to goo if it is ever sat in water for any period of time liquid will find a way through the best water prof layers.
It might sell as is to fund the material's you need,A good quality Marine Plywood would last much longer.


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## grance (Feb 16, 2015)

nice box id sell it before messing it up 75-150 dollars


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## 4metals (Feb 16, 2015)

The box is obviously a big old speaker housing and I agree with Justin, the thing will turn to mud if any liquid seeps through your lining. 

The look of it reminded me of a glove box. A glove box is an enclosure where you have access to handle what is going on inside by using 2 gloves mounted into the unit. Sand blast cabinets use this design. Professionally made they are pricey.

But what if you used a see through large plastic storage container like they did in this link. http://www.shroomery.org/forums/showflat.php/Number/17347745 I have a friend into mushrooms and he made one of these for innoculants. 

Cheap to make and it can have a small exhaust that is scrubbed so the fuming can't escape without being scrubbed. This one is filled and emptied by lifting the inverted container off the lid but an airtight lid could be fashioned from some plastic boating hatches.


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## NobleMetalWorks (Feb 16, 2015)

If your intent is to make a fume hood out of wood, I would also consider coating the inside or any surface that will be exposed to gases, with something that will resist the gases we produce when dissolving metals in AR.

The reason for my suggestion is that by dissolving, lets take for example gold, in Aqua Regia you also produce a gas that contains Chlorine (Cl2), nitric oxide (NO), and nitrogen dioxide (NO2). The NO will cause the wood to become a Nitrocellulose, here is information on the subject:

http://en.wikipedia.org/wiki/Nitrocellulose

I believe if I remember correctly, that there are a few posts about this here on the forum, one being someone who left a cloth rag on a hot metal car hood, or something like that, that ignited on it's own after it had been exposed to Nitric Oxide and turned into Nitrocellulose.

You wouldn't want a temperature change to cause your hood to ignite in this way.

Scott


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## Palladium (Feb 16, 2015)

I laid some cardboard (boil over ) that had been soaked in nitric from a gold filled lot on a stainless sheet in the sun to dry. I went out to check on it about 2 hours later and it had self combusted.


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## Profikiskery (Feb 17, 2015)

There are many posts here on fume hoods and I would venture to say I have read them all. Most seem to be about design, or how to accomplish the Venturi effect, or members having issues with their own builds seeking help. I either missed or could not find anything on construction and materials used. I saw many pictures of builds in progress, and looking at the pictures, those units seemed to be being constructed of wood, either pexi or glass, and PVC for exhausts and duct work. Wood is my only option as I don't posses the ability or tools to build with pexi or glass.

I figured if I coated this thing with about a 1/4 inch of bedlinder, and topped it off with Amazing Goop Epoxy Sealant, it would last a long time. The Goop is not only acid resistant, but waterproof as well. Check out this link....http://glazecoat.com/amazing-goop-epoxies/ . I know my experience in this forum is limited, but between the liner and the Goop it seems it would be very resistant....

Do you guys not think that would hold up....or be subject to Nitrocellulose? I can never see myself processing more than 32ozt silver a month if that. If not I'll go back to the drawing board. 

Thank you all again for your input,
Craig


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## kurtak (Feb 17, 2015)

kurtak said:


> Anything metal would need a chem resistant coating both inside & out
> 
> Kurt



opps - when I read "bass cabinet" I thought it said "brass" cabinet - but its a "base" cabinet

Kurt


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## justinhcase (Feb 17, 2015)

Wood is Good,but do not use any particle board as it may be cheap but that is for a reason.
Use a good Marine Plywood as it is already impregnated with epoxy so will stand a lot of chemical exposure.
Your filler will be good for sealing up cracks and joining P.V.C. tubing to your cabinet,a slight gradient will let you to put in a gutter to catch any spills in a trap.
But I would think that a heavy duty two part epoxy paint would be the best way to seal all the surfaces.get more than you think you will need as it soaks in to the wood more than you would think which is what you want.
http://www.ebay.co.uk/itm/EPOXY-RESIN-GARAGE-INDUSTRIAL-FLOOR-PAINT-GLOSS-/321093866615?pt=LH_DefaultDomain_3&var=&hash=item4ac2af9477
When it get's tatty just rub down well process the dust for P.M's and repaint,at the end of it's long life you can even burn the hole unit to make sure you get every last trace of value left.


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## Profikiskery (Feb 17, 2015)

Thanks guys Marine Plywood it will be. I don't want to be doing this again in ten months.

I have one more question. Below is what I want to build based on 4metals design. I made my opening much smaller but left my self some room inside....notice 15 inches on both sides of the opening. Even though I got some cubic ft in there, as long as my opening is 1.5ft X 1.5ft am I ok with a fan that moves a little over 300CFM? I already have the fan so I made my opening smaller to accommodate that..cant see in the picture but it will be 36" high

Thanks,
Craig


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## justinhcase (Feb 17, 2015)

If you make a false back to the cabinet you can draw air evenly form all around your cabinet.


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## Barren Realms 007 (Feb 17, 2015)

Profikiskery said:


> Thanks guys Marine Plywood it will be. I don't want to be doing this again in ten months.
> 
> I have one more question. Below is what I want to build based on 4metals design. I made my opening much smaller but left my self some room inside....notice 15 inches on both sides of the opening. Even though I got some cubic ft in there, as long as my opening is 1.5ft X 1.5ft am I ok with a fan that moves a little over 300CFM? I already have the fan so I made my opening smaller to accommodate that..cant see in the picture but it will be 36" high
> 
> ...



Calculate your air movement at 100CFM per sq. ft. of your front opening at the minimum.


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## 4metals (Feb 17, 2015)

It is common to have a hinged door to cover part of the opening. The one thing refiners experience is clutter in the hood and it could be a challenge removing a bucket out of a small opening (in your case 18X18) especially when you have it pushed to the side of the hood, not directly in front of the opening. Considering your hood will be much larger inside, I would consider an opening 2 feet high by 3 feet long. This would require an exhaust of 600 CFM when opened. Next, I would add a hinged Plexiglass door 3 feet long by 1 foot high. When the hood has the plexi door down the 300 CFM will suffice. 

Since the full open door will only give you 50 CFM per sq ft of opening, *you have to be smart about it.* Don't open the upper door and remove things when a reaction is running full speed, just reach under the plexi door and still have access as needed. 

This approach will give you more room for handling buckets in the hood than the smaller door and still allow you to add chemicals and move things in the hood through the bottom portion of the opening. 

This may not be important to you, but I know that I would be inclined to have more than less inside my hood and that is easier to work with a larger door. Remember, if the reaction is running, keep the plexi door down and you will still have a 3 sq foot opening and 300 CFM. Only open it fully as needed to pour and manipulate reactions that have past their active phase.


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## 4metals (Feb 17, 2015)

Another option would be to use a track on top and bottom of the oversized door. Then add a plexi sheet 18" by 2 feet tall which is not removable. Wherever it is on the opening it is blocking 3 square feet so you can move it to the left to work on the right side and move it to the right to work on the left side. 

This option always maintains the CFM required through the opening. 

Please realize whichever of these methods you choose, or even if you just use your 18 by 18 door, you are not scrubbing any fume. You will be best served by exhausting the 300 CFM through the hood to maintain your work environment and exhausting your reactions separately through a scrubber. There are some very effective scrubbing options that work well for small operations posted already on the forum.


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## Profikiskery (Feb 17, 2015)

4metals that last post is a shin-diggity idea!! It would give me a little more peace of mind with the smaller fan I have. 

As far as the scrubber goes, I have spent maybe an hour so far here in the forum and on the web reading about them, but still have absolutely no grasp yet of how they work or how to incorporate them, so I need to do some more reading. If I get stuck or don't understand then I will post. I will say I am struggling in that area. I look at the set up and diagrams of others here and it is a bit overwhelming to me, having no knowledge at all. Not looking for answers yet as I need a bit more time to try and get a grasp, but questions might come on down the road.

In the meantime let me ask something. Can I add a scrubber later without much hassle, or is that something that would be easier accomplished, (and less expensive) to do from the get go? 

Thank you guys for sharing with me...and one day I will post pictures of my new hood. I will share something back. It sure is nice at 51 years of age to find something to get all giddy about. I haven't had proper sleep in a month...and I am good with that!!

Thanks again all,
Craig


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## 4metals (Feb 18, 2015)

A scrubber needs a separate exhaust to power it, either by vacuum eductor or a small fan. It can be added later without changing the economics.


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## rickbb (Feb 18, 2015)

I second the hinged or sliding opening in the front. In fact I would make the entire front able to be opened when needed.

I've worked in more than a few fume hoods and you always will have times when you need as much access as possible, (cleaning and setting up for instance), and other times when you need the maximum fume extraction, (when a digestion is active for instance).


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## kurtak (Feb 18, 2015)

rickbb said:


> I second the hinged or sliding opening in the front. In fact I would make the entire front able to be opened when needed.
> 
> I've worked in more than a few fume hoods and you always will have times when you need as much access as possible, (cleaning and setting up for instance), and other times when you need the maximum fume extraction, (when a digestion is active for instance).



correct - I have mine built so I can slide the door to ether side (left or right) a lot or a little - or take it completely out of the way 

Kurt


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## Profikiskery (Feb 18, 2015)

Thanks all for the input on this post. I have a lot to do and am excited to get started. Was talking to a friend of mine today who is a plumber and he is willing to help me with the exhaust system and install the drain at the bottom. Film at 11!

I certainly appreciate the time you guys shared to help,
Craig


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## 4metals (Feb 19, 2015)

A drain can be your best friend.....or your worst enemy. When you have a spill, and you will if you do this long enough, you want to think containment. 

If you have a drain but the thing is plumbed into a drain system, it's an invitation to a loss. (Both financially and environmentally!) If it sits over a bucket or a drum, still a potential for a loss. You know, when you need the bucket for something else just when you have a spill. 

I like a drain but I also like to know anything spilled is contained. 

One option if you want to have the drain is to have it flush in the bottom and have a 2" stand pipe which you can remove if you wash down the hood but use it when operating. It prevents any spills from flowing down the drain, (into the bucket) until they are deeper than the volume of the base of your hood and 2" deep. A 4 foot by 3 foot by 2" deep catch is just shy of 15 gallons. If you have a spill that big you should consider taking up knitting! 

I would also offset the drain so it is not right where you are working, especially if you go with a stub up which will be sticking up 2".


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## kurtak (Feb 19, 2015)

4metals said:


> A 4 foot by 3 foot by 2" deep catch is just shy of 15 gallons. If you have a spill that big you should consider taking up knitting!



:lol: :lol: :lol: its a good thing I didn't have coffee in my mouth when I read that - my computer would have just got a shower :lol: 

Kurt


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## rickbb (Feb 19, 2015)

When I ran a nickel plating operation the local fire department/hazmat inspector made us take the floor drains out and put in containment sumps. We also had to have enough neutralizing absorbent sock type of spill booms on hand to absorb or contain a spill equal to the volume any one of the plating baths.


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## 4metals (Feb 19, 2015)

Usually containment has to be 110% of the volume of the largest tank. The neutralizing absorbent socks can wreck havoc on any attempts to recover precious metals from the liquid. 

But in a sprinklered building, if the tips go off, there is no containment big enough. The fix causes more problems than the problem.


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## Profikiskery (Feb 20, 2015)

My thought on the drain was this..

Understand first I am new...on about page 70 of Hoke's book and reading here quite a bit, but new. I have found the fluid is adding up fast. What I mean by fluid is the part where I have dissolved the silver and placed the copper in for cementing. Right now I have those jars outside during that process. Even though there is no fumes I can detect, and even after two days when there seems to be no more reactivity I am wary of those jars because I just don't know if there is any trace coming off of there I can't see. 

When I decant I wear a respirator for that reason...it scares me a bit because of my lack of knowledge. So I want to do all that in the hood I guess as I would feel better. 

My thought with the drain was to mount it flush...with a valve that turns it on and off underneath. So after all the rinsing and and silver recovery...when its time to go into my stock pot it could all be done in there...i.e. I can just pour off the waste via the drain inside to the fitted container. That way from start to finish....it is all done in the hood. The drain... would remain closed the rest of the time in case of a spill. That is why I was thinking of the drain. Forgive me for my laymen terms...but I did want to share. Any advice or comments I certainly appreciate...I am just trying to learn as much as I can.

I sure thank you all for your input and look forward to the day when I make a post that helps out another member. For now... I am definitely riding shot gun.

Much appreciated,
Craig


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## 4metals (Feb 20, 2015)

A shut off on the drain works but keep it in a place where it is always easy to see it, this way you can glance and make sure it is closed when you are working. 

I have found if something is not easy to verify, it doesn't get verified. Until there's an OH S*** moment! and then it's too late.


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## Profikiskery (Mar 9, 2015)

Hello members,

Guys... I am just a few days from starting my hood, but I want to do this right. A few things I want to be SURE of.

Even after much reading I am still a bit confused on what I need to be moving CFM wise. I guess I might be trying to have my cake and eat it too, So I want to make sure I am right.

Is CFM based on the opening to the fume hood, or the cubic feet inside the hood? My fan pulls 325 CFM. My plans are for a hood 48" wide, 22" deep, 36" tall with a crest like a dog house (see rough sketch). That gives me a lot of room inside. However, and understand, was only going to make my opening 18" X 18" to accommodate the fan.

Based on my opening will that be enough to accommodate the square footage inside the hood? I plan to incorporate the sliding door as suggested by 4 metals but have read some posts that have me doubting I might not have enough fan. Is it true that Nitric fumes are heavier than air and will fall to bottom of hood, possibly coming out?

Every post I have read doesn't really say, and videos I have seen does not show this is true, but it could be because they have enough fan to get it out. 

I am. and have been reading like crazy about fume hoods. I am fixing to start and do not want to have to do this twice so in advance I apologize for asking questions that might already be here. If I do....its not because I haven't looked. 

ANY advice is appreciated,
Craig


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## FrugalRefiner (Mar 9, 2015)

Craig, the air movement needed is based on the opening size. The general rule of thumb is 100 cfm for each square foot of opening, so with an opening of 1.5 ft by 1.5 ft (18" x 18") you have 2.25 ft2 of opening. 325 cfm should serve you well. 

You may find that opening a little tight once you start trying to move things to the back corners of the cabinet.

Dave


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## Profikiskery (Mar 9, 2015)

Okay Dave and thanks for clarifying. I do realize I have to sacrifice a bit on the opening compared to the room inside but I am happy and think it will work ok for my needs. I think I got everything covered. As I piece my ventilation (which will be awhile), I might post a few more questions I am still not sure of. Still reading up to the minute. Its going to be a good one!!

Ok guys, I am on it. Film at 11. I am so excited!!! 

Craig


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## METLMASHER (Mar 10, 2015)

*<EE>* Shaped like that would give more room for two arms. During a reaction is no time to be cramped, or worse - awkward.


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