Building a process cabinet, advice needed please.

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Snapperhead

Member
Joined
Oct 5, 2013
Messages
8
I want to build a cabinet that I can use to contain an accidental spill while doing various processes, or at least give me some extra time for containment or evacuation if needed. I would like it to be sealed off with a positive pressure fume hood, with both power, water, and waste sump inside. I would like to know any advice you have on the most suitable materials to use and also a good size to start with. I am still in the learning and equipment building stage, and I would like to make myself a safe work zone when processing the plated pins, fingers, IC's, and later Pd and Ta caps (around 2Kg of each per run).

Its not that I am clumsy, I live in a place that has the occasional earthquake, and I want to be prepared if it happens again.
Thanks
 
Snapperhead said:
I want to build a cabinet that I can use to contain an accidental spill while doing various processes, or at least give me some extra time for containment or evacuation if needed. I would like it to be sealed off with a positive pressure fume hood, with both power, water, and waste sump inside. I would like to know any advice you have on the most suitable materials to use and also a good size to start with. I am still in the learning and equipment building stage, and I would like to make myself a safe work zone when processing the plated pins, fingers, IC's, and later Pd and Ta caps (around 2Kg of each per run).

Its not that I am clumsy, I live in a place that has the occasional earthquake, and I want to be prepared if it happens again.
Thanks
I think you mean a negative pressure hood that will draw air into the hood collecting fumes and removing them to a safe area.
Positive pressure will blow the bad stuff in your face.
 
Thanks for that, I wanted a positive pressure unit to keep the fans upstream of the fumes, rather than exposing them to the corrosive elements in the vapor. I had hoped to have the gloves bonded to the front of the cabinet so all work can be done inside without getting near any fumes (fans will be shut down when opening the cabinet for loading and unloading)
 
It would be my opinion that you should lose the idea of a positive pressure hood. It will have far too many leaks where they are not wanted to be effective, and you'll suffer far more than you might imagine. You'll understand this a little better once you start working with HCl or ammonium hydroxide. That would be particularly true when dispensing these solutions. The very best scenario is that you work in the opening of a hood that is capable of removing transient fumes. That can't be if the hood is pressurized.

Harold
 
Yep, ya went the wrong way back at the fork in the road, just back up and go the other way. There are plenty of examples of fume hoods here on the forum let alone the rest of the internet, to get some good ideas.
 
If you have concerns about fume damage to the blower in a negative pressure system, you can use an Air Eductor to create the protection you are wanting.
Personally, I can get the blowers cheap enough, I just replace them when they rot (decompose) to the point of failure :lol:
Here are 2 pics I found by googling the term " Air Eductor "
 

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Thank you, I now understand the flaw in my initial plan. It will be negative pressure, using a fabricated eductor. It works out better this way too, as I can have the fan mounted behind the wall to cut down on noise in the workspace I am presently building.
I was discussing the cabinet with a veterinary friend and he told me, that the ones at his university had a glass front panel that slid up to allow access. It will be simple to build something along those lines, using a couple of pulleys and counterweights attached. The bonus for me is that I don't have to try and bond the gloves to the cabinet anymore.
I have a decent quantity of stainless steel ducting that I can use for the flue, and I need to ask for your experience, whether there is a better choice of material for the exhaust ducting ?
Again, thank you for any advice.
 
Snapperhead said:
Thank you, I now understand the flaw in my initial plan. It will be negative pressure, using a fabricated eductor. It works out better this way too, as I can have the fan mounted behind the wall to cut down on noise in the workspace I am presently building.
I was discussing the cabinet with a veterinary friend and he told me, that the ones at his university had a glass front panel that slid up to allow access. It will be simple to build something along those lines, using a couple of pulleys and counterweights attached. The bonus for me is that I don't have to try and bond the gloves to the cabinet anymore.
I have a decent quantity of stainless steel ducting that I can use for the flue, and I need to ask for your experience, whether there is a better choice of material for the exhaust ducting ?
Again, thank you for any advice.
For the exhaust, try to use as much plastic, PVC, CPVC or even fiber glass as possible. Any fumes will react with the metal.
The most common acid fumes you will be dealing with will be HCL (in my case) which will attack the stainless steel you mentioned.
The picture is 12 inch sewer pipe used by the city sewer system. My son works for them ans these were scrap. He is going to bring a 14 foot long piece for my exhaust riser. This stuff will last forever with these chemicals. If you can locate an end piece left over from a job site will save you a lot of money in the long run.
 

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A very recent post on the same thing: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=40&t=19496
 
Thank you so much, I do have access to large diameter PVC pipe and I have worked with it for years, so fabricating the flue from it will be a lot easier than using metal. Knowing that epoxy resin and fibreglass is suitable for fume hoods also changes everything (I worked in the family boat building co for years). This allows me to fabricate the entire cabinet from plywood, and layer it with resin and mat. Even the eductor could be formed from the cardboard based form tubes (used in concrete construction), and then layered with resin and glass.

Thanks Smack, I did miss that recent thread (my search words were way out). The PDF fume hood guide was just the article I was hoping to find, and reading other build threads has given me some great insight. I will read through it a few times today.

Thanks for your patience with me.
 
I used my fume hood for incineration. I also set fire to my first lab, because I used my fume hood for incineration. In this case, it was made of fiber glass, which I do not recommend if there's going to be extensive heating. My third generation fume hood was built entirely of asbestos. That's likely next to impossible today---but it was 100% safe for the intended purpose.

Harold
 
Harold_V said:
I used my fume hood for incineration. I also set fire to my first lab, because I used my fume hood for incineration. In this case, it was made of fiber glass, which I do not recommend if there's going to be extensive heating. My third generation fume hood was built entirely of asbestos. That's likely next to impossible today---but it was 100% safe for the intended purpose.

Harold
Harold,
I see you are one of us after all.
OK, I didn't set my shop on fire but I did rust-out over $100,000.00 worth of tools and metal supplies by running an AP tank with-out proper ventilation inside my shed.
Sometimes we learn the hard way. :lol:
 
niteliteone said:
Harold,
I see you are one of us after all.
Indeed I am. Last time I checked, I couldn't walk on water! :lol:

Key here is that one learns from negative experiences. There wasn't much good I could say about my first hood. I used a squirrel cage blower for ventilation, which quickly got plugged and ran with a lot of rumble. The hood didn't have any filtration capability, so when I cleaned out the blower, I was pleasantly surprised to discover there was value in the accumulated dirt--but then I could only wonder how much I had lost over the period of time it was in use.

As I said, if one learns from these experiences, no big deal. Education isn't free---you'll pay one way or the other.
OK, I didn't set my shop on fire but I did rust-out over $100,000.00 worth of tools and metal supplies by running an AP tank with-out proper ventilation inside my shed.
Sometimes we learn the hard way. :lol:
That's a lesson hard learned by many. One does NOT store HCl in a closed environment, unless there is little of value that can be destroyed. It fumes, even from closed containers.
I ran my fume hood almost non-stop. The lab existed in the castle for ten years. In that time, the window frames, which were anodized aluminum, were pitted, although not badly. Any ferrous material was rusted to some degree, even some stainless hardware I had made, secure in the knowledge that there most likely would be some serious corrosion, in spite of the fact I had taken every possible precaution. I had even isolated the lab from the balance of the structure, and provided its own heating system, so no air would be shared by the balance of the structure. That part worked very well, by the way. There was no corrosion or rusting of any description outside the lab.

Harold
 

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