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Harolds Blower Fan

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dick b said:
Hello Harold:

Ouch!!!

I didn't see that arrow coming, direct kill to the heart.
Not meant to discourage you, Dick, just a heads up. It will serve you perfectly well assuming you can get it coated fully, and you don't incinerate. There are few, if any, chemically resistant coatings that are at your disposal that will tolerate the heat involved in incineration. Besides, how we learn what works, and what doesn't, is by experimentation. My hood evolved from previous mistakes, so hang in there.

Let me give you an idea what I'm talking about.

My first hood was made of fiber glass, which I eventually set on fire while incinerating polishing wastes. I was lucky. The flames didn't destroy my garage (and attached house).

That hood was replaced by one made entirely of asbestos, although not a great design. It was, however, instrumental in my final design, which functioned quite well.

Anyway, back to the first and second generation of hoods----my hot plate was mounted on a countertop of particle board, which, in turn, was covered with a sheet of 3/8" thick asbestos (Transite). After prolonged incineration, I would get the faint smell of burning wood in my lab. Only when I moved did I discover the source, although I had a strong suspicion of what was happening. Under the Transite, there was a round scorched area about the size of the pan I used to incinerate. It had nearly penetrated the particle board, at which time I have little doubt, I would have experienced a fire. Because the Transite covered the particle board totally,there was no source of oxygen.

My point is, even if you can coat your board, it won't be resistant to heat in a meaningful way. It won't burn, but incineration will destroy the coating. That, in turn, will allow HCl to rapidly destroy the board.

I have every confidence that, assuming you seal the surface well, and you don't overheat the board, it will serve you quite well. Be advised, however, that the slightest break in the coating will lead to rapid deterioration of the board. It might serve you well to put a few drops of HCl on a small piece to see the reaction.

For the record, even Transite had a finite life. Incineration kept it somewhat dried out, but anywhere I used Transite, the bonding cement was slowly dissolved, liberating asbestos fibers. The top of my fume hood had lost about 20% of it's thickness in the years it was in service (about ten years). There are other forms of asbestos that appeared to be more resistant. The front and back panels of my hood were made from a different formulation, and had totally resisted both heat and acid. I used material that was at my disposal, for when I built my hood, asbestos was already being rapidly removed from the market. I was lucky to get what I got.

Mean time, luck with the hood!

Harold
 
Hello Harold:

When I decided to build this hood I had two primary goals in mind, Very enviromentially friendly and safety. I also wanted to keep the cost to a reasonable level. I looked a long time for a product that would meet these goals and finally settled on hardiebacker as the best choice. It meets the fire safety qualities that I was looking for and I felt that I could deal with the fume issues with epoxy paint.

I expect that I will be able to keep surface temps below 150* F with sizing the heat source and air gaps to the surfaces. Along with sufficient air flow to carry generated heat away. I won't know this untill I finish the hood and test it out.

I bought a propane hot plate from Northern Tool that I think is similar to what you were using.

http://www.NorthernTool.com Item # 330971

I think that I need to say that I only intend to do inceneration on small quanities in a small 8" SS frying pan at a time. The same goes for refining, distilling and melting. Keeping reactions to a 2L vessel and 5 toz quanities at a time.

Again, this is only a hobby, not a business for profit.

I am using pawnbrokerbob's AB train as a way to contain fumes and recover as much as possible inside glass before sending it to the scrubber for cleaning.

I can send you photo's as I progress via email if you PM me your address.

As to fume degradation, if the epoxy doesn't provide the protection to the hood that I expect. I can line it with ceramic tile, or use the spray on bed liner that we have been discussing in the build a hood/scrubber thread in this heading.

I have sized the hood to include 2 fiberglass filters at the top and back of the hood to catch large particulates. It will have a window for a 2 tube 48" light fixture on top and the front will have 2 glass / lexan swinging doors to close the opening during reactions. I don't have head room over the hood to use a slide up door like lab hoods use.

I'm trying to keep the air flow to a minimum to reduce room heat loss and the need for large make up air requirements.

I've been thinking about this for over a year now and this is the fruits of all that has been offered here on the forum and my experience.

I'm sorry for the length of this post, but I am trying to be as clear to the forum as I can be without having completed the hood and tested it yet.

As with any prototype, testing after it's build will be the key to meeting the intended goals. After it's finished and I'm satisfied with the results, I intend to offer the photo's and dimensions to the forum for their use to copy or modify.

dickb
 
asbestos, still a great product, I dont think much can replace this rock for its fireproofing and other property's, I have worked with it for years, in boiler refactory, and steam piping insulation,insulations in houses, mechanical work and such, used to be so many things used this useful rock, even floor tile. I remember working in room full of dust floating in the air we breathed, that was before it was considered so deadly, or at least as we were aware, the dust in lungs surely will cause lung cancer, I believe this, and wished would have known that fact years ago, asbestos can still be found all over, old metal flammible fire proof cabnets used to store gasoline and flammible liquids, had sheet asbestos inside between double walls of metal cabinet, some old cooking stoves used these sheet boards also, used in houses behind the wood stove, old house sideings used asbestos square sheet tiles, if working with it wet it down to pervent dust, wear a dust mask, and remember if it's on your clothes even wet and if brought into the house or where ever and it drys out it can then be dust in your home,looking at it won't kill you. but take precaution if you do work with it.
 
I went to my local hardware to buy filter for my fume hood.
There was fiberglass filters that I think would be good.
They looked very thin I think if i had a few of these it would be better.
Also the filters had a frame that was from paper.
I suppose if I made a frame from steel and painted it with epoxy paint that would be ok.
Thanks
 
Hello:

I sized my hood to allow two 14" x 25" x 1" thick fiberglass pleated filters to fit across the top back cornor of the hood. The top of the filter projects about 6" from the back wall and the bottom is attached to the back wall. I made the frame that holds the filters out of the same hardie backer board that the hood is made of. When done all of the inside of the hood will be painted with white epxoy appliance paint to reduce acid and base fumes from attacking the backer board. The exhaust from the hood is in the triangle shaped area at the top of the hood behind the filters.
I expect that the filters will trap mostly smoke from incineration and larger airborne particles.

dickb
 
carbon filters would most likely trap values, maybe little costly but.
industrially we use filter boxes that we put our activated charcoal in, the charcoal comes in 55 gallon drums, fish supply store sell carbon filters also not sure if they can be adapted for use here?
I think carbon can also collect some of the smelly acidic fumes.

edit something to consider on second thought is if using nitric or strong oxidizers this may not be safe, depending on what fume hood is used with and how. so consider this before using any organic materials in your fume hood desighn, wood paint and other organic materials with a plastic fume hood and nitrates can get to become dangerous combinations.
 
butcher said:
so consider this before using any organic materials in your fume hood desighn, wood paint and other organic materials with a plastic fume hood and nitrates can get to become dangerous combinations.
I had a hood fire. Nothing will prompt an individual to build a suitable fume hood like watching their house go up in flames.

I'm hard headed as hell about what constitutes a proper fume hood, especially if you intend to use it for incineration. Consider my near disaster when you think I'm harsh on those that make compromises. I'd hate to see anyone learn the lesson the way I did.

Harold
 
Refiner232121 said:
I went to my local hardware to buy filter for my fume hood.
There was fiberglass filters that I think would be good.
They looked very thin I think if i had a few of these it would be better.
Also the filters had a frame that was from paper.
I suppose if I made a frame from steel and painted it with epoxy paint that would be ok.
Thanks
Remember that you have to process these filters for values. Those made of paper are just fine, assuming they are well away from direct heat. One is adequate, for it quickly loads with debris that slows filtration. No harm in using more than one, assuming you have room. They can be progressively moved so the first one in is the first one out.

Do not worry about those that have perforated metal that holds the fiber glass. In fact, I preferred them for they prevented a blow-out of the filter, which happened occasionally with those made of paper if I didn't get the filter changed in time.

When you incinerate the filter, the glass collapses to dust readily, so they break down to just a small amount of residue. That residue is best run in a furnace to recover values, assuming you heat the fiber glass to the point of melting, which I did. Some of the values get trapped in the melted glass fibers, so you can't recover it with acids. The added glass becomes a part of your flux, so it's a positive in all directions to use fiber glass furnace filters.

The perforated metal face pieces will fold up nicely to a small packet after incineration, which can then be used as scrap steel for your stock pot, so you recover any values that hitch a ride in incineration.

Harold
 
Hi Folks and Harold
Thanks for your helpful tips.
I went on Google searching for asbestos
All I could find was info about how people are still dying from this mineral.
I am sure it is a big concern when you have asbestos linings of air circulation systems
When the dust is in the air all the time it is a nightmare.
What do we do as an alternative
I would like to incinerate
Dickb has found that material that wont burn
But Harold said it will fall apart.
I said maybe I can build something small just for incineration.
Buy some fire bricks and make a furnace
Thanks
 


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