# My "LAB"/Exhaust Hood/Concerns



## Planet Rock (Oct 20, 2012)

Hi Folks,

This is my first post. I ran into all this because after being offered a low price on 14g of scrap 18k (about $500 worth of pure gold), I poked around on the web, and now I'm becoming a gold recovery chemist (along with the other millions of things I'm involved in!). I can't help myself. :roll: 

I am considering building a small room in the right rear corner of my garage. We hang our clothes to dry to the right of the garage, as you can see. The room would be about 8 x 10, just enough to do some simple recovery and refining. I'll insulate it and heat it (and AC in summer) so that I won't suffer too much. I'll have some bench space with an exhaust hood. I can build that and test it to make sure the fumes are going out. That's no problem. And, we live in the woods, and there are no neighbors for hundreds of yards. Here are my concerns:

1) Is there a recommendation for a brand name and model of an exhaust fan that has chemical-resistant parts (plastics and rubber), where the motor is isolated from the fume path?

2) I know the fumes are bad. I fully understand the risks. We use lye all the time with our soap-making business. I understand that these fumes are much worse. Now, I know some people just do this outside, and avoid the fumes by standing upwind, etc. But what I want to know is, how bad are the fumes five feet away from the source? How about ten feet, or twenty feet away? If I run a PVC pipe out through the metal roof of the garage, and the fumes go out of the stack, what should I be concerned with? We live in the woods, and there are no neighbors for hundreds of yards. Some people use scrubbers, but why would this be necessary? Only for certain chemicals? Will the fumes hurt my metal roof, or, the clothes that are hung out to dry? Do the fumes turn liquid and drip off the end of the pipe? What type of cap should I have on the end of the pipe stack? Is there a safe way to do this with what I am considering? Could I run the pipe very high or even off to the side so that the fumes are not a problem?

That's a lot to ask, but I haven't found these answers yet. Thanks so much. If I have violated any policies, I apologize in advance.

Charlie


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## RikkiRicardo (Oct 20, 2012)

what is the million dollar question
sorry search the forum
study
acids will kill you learn what you want to do..


Rikki


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## NobleMetalWorks (Oct 20, 2012)

Planet Rock said:


> Hi Folks,
> 
> This is my first post. I ran into all this because after being offered a low price on 14g of scrap 18k (about $500 worth of pure gold), I poked around on the web, and now I'm becoming a gold recovery chemist (along with the other millions of things I'm involved in!). I can't help myself. :roll:





> I am considering building a small room in the right rear corner of my garage. We hang our clothes to dry to the right of the garage, as you can see



Wherever you vent your exhaust, you are not going to want any of it to blow on clothes that are drying. Not only will your clothes readily soak up the NOx fumes, but they will be captured as weak nitric acid. Which could create Nitrocellulos http://en.wikipedia.org/wiki/Nitrocellulose. You can do a search on the forum and read actual events experienced by members here. You also have trees close by, this could affect them in the same way, the gas could also kill plants in the immediate area.



> . The room would be about 8 x 10, just enough to do some simple recovery and refining. I'll insulate it and heat it (and AC in summer) so that I won't suffer too much. I'll have some bench space with an exhaust hood. I can build that and test it to make sure the fumes are going out. That's no problem. And, we live in the woods, and there are no neighbors for hundreds of yards. Here are my concerns:



If you build a fume hood yourself, you might want to do so out of material that will not create Nitrocellulos. Anything out of wood that isn't coated will cause Nitrocellulos to be created.



> 1) Is there a recommendation for a brand name and model of an exhaust fan that has chemical-resistant parts (plastics and rubber), where the motor is isolated from the fume path?



There is a lot of information on the forum if you use the search tool, about fume hoods, building fume hoods, how to vent fume hoods. There are even a lot of pictures. There are several ways you can vent the gas, the key to venting from your fume hood directly into the atmosphere without a fume scrubber is air volume. The more air you are moving, mixing with your fume hood exhaust, the less PPM of NOx you are going to have.



> 2) I know the fumes are bad. I fully understand the risks. We use lye all the time with our soap-making business. I understand that these fumes are much worse. Now, I know some people just do this outside, and avoid the fumes by standing upwind, etc. But what I want to know is, how bad are the fumes five feet away from the source? How about ten feet, or twenty feet away?



When you state:


> I know the fumes are bad


 that could be called the understatement of the year. Fumes created from refining precious metals are not just merely bad, they are deadly. Meaning you could literally die, or be harmed to the point where you shave several years off your life. You are also talking about a gas. During WWI when gas was released to gas the enemy, sometimes it blew back on who released the gas, and ended up killing the wrong people. To ask how close you can be is really a question that cannot be answered. If you have no wind then the gas might stay concentrated, if you have the right wind, it might carry a cloud 20 ft away. If you are standing upwind from the reaction then it wouldn't matter, if you are doing this under a fume hood, correctly, then it shouldn't matter. The idea is to remove the gas from your area. After all, what good would standing 20ft away do when you cannot observe your reaction?



> If I run a PVC pipe out through the metal roof of the garage, and the fumes go out of the stack, what should I be concerned with? We live in the woods, and there are no neighbors for hundreds of yards.



For discussion sake, lets just talk about the affects of NOx gas, and not all the other dangerous gases that are created. NOx is highly corrosive, it eats metal like candy. If you have anything metal around, and there are any NOx gasses in the atmosphere, they will corrode and eat away at the metal. Electrical switches, cars, tools, pipes, the roof of your garage, literally anything made of metal. The trees close by will also be affected by NOx. I personally know someone who was reacting things in their backyard and ended up killing their garden because NOx is heavy, and likes to stay close to the ground if given a chance. I cannot stress this enough, NOx is highly, highly corrosive.



> Some people use scrubbers, but why would this be necessary? Only for certain chemicals? Will the fumes hurt my metal roof, or, the clothes that are hung out to dry? Do the fumes turn liquid and drip off the end of the pipe? What type of cap should I have on the end of the pipe stack? Is there a safe way to do this with what I am considering? Could I run the pipe very high or even off to the side so that the fumes are not a problem?



Fume scrubbers insure you are not releasing poisonous gases into your environment, if you use an enclosed system, a reaction flask, a condenser and fume scrubber, you don't even need to use a fume hood for aqua regia dissolving. This would also condense NOx coming out of the reaction vessel so that it is returned to the reaction as nitric acid. It's a lot more efficient and you use less nitric acid. You can also use your waste solution in your fume scrubber once concentrated enough, as a weak nitric acid to dissolve base metals in other material.



> That's a lot to ask, but I haven't found these answers yet. Thanks so much. If I have violated any policies, I apologize in advance.
> 
> Charlie



Best possible thing you can do, before you do anything else, is to read C. M. Hoke "Refining Precious Metal Waste". At the very least you should do the familiarity tests, and pick up the language we use here on the forum to explain things. This way if you do run into a problem you can effectively explain the situation using terminology that we all understand and agree with here on the forum. There is a huge wealth of information on this site, and probably every one of your questions can be answered just by searching.

And welcome, hope you stay and learn and become an active member.

Scott


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## Planet Rock (Oct 20, 2012)

Hi Scott,

Thanks so much for your answer, it was extremely helpful. I do want you to know, however, that I understand how corrosive, dangerous and deadly these fumes are, that's why I have these concerns. I will do a lot more searching. And, I do need to get to know the jargon. I'll get Hoke's book, and I'll be studying that as well.

Charlie


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## NobleMetalWorks (Oct 20, 2012)

Planet Rock said:


> Hi Scott,
> 
> Thanks so much for your answer, it was extremely helpful. I do want you to know, however, that I understand how corrosive, dangerous and deadly these fumes are, that's why I have these concerns. I will do a lot more searching. And, I do need to get to know the jargon. I'll get Hoke's book, and I'll be studying that as well.
> 
> Charlie



Sorry Charlie (Pun intended, I just couldn't help myself but no worries, I won't talk about Tuna)

Whenever I take the time to answer a post like yours, I do so with the thought that other less knowledgeable or experienced people may read this post later. You seem to be aware of the issues and problems, I apologize if I made it seem like you were not. Obviously you are being very careful and wanting information before you even start, which is far more than what most people do. 

I hope you do well and stick with this, so many people jump in feet first before reading and learning, and end up quitting before they ever really start. You seem however to be on the correct path.

Scott


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## AndyWilliams (Nov 12, 2012)

Planet Rock said:


> Hi Scott,
> 
> Thanks so much for your answer, it was extremely helpful. I do want you to know, however, that I understand how corrosive, dangerous and deadly these fumes are, that's why I have these concerns. I will do a lot more searching. And, I do need to get to know the jargon. I'll get Hoke's book, and I'll be studying that as well.
> 
> Charlie



Hey Charlie, good to see another Badger here!


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