I put together my first one in about 4 hours of actual labor, it's not hard to do if you have your plans all laid out.
I made my own eductor on the first one, it ended up costing me around $20 dollars. If you purchase them, they are more expensive, naturally. But they work more efficiently. I was playing with the idea of buying a small mill, and some PVC and trying to mill my own, but that's a project best left for another time currently I am just trying to get an assay lab up and going now.
There have been some posts I believe about building a lab in a garage. I am looking for the right building to rent currently, but I am still going to keep my garage lab. I was originally going to install a 6ft fume hood. Here are the two I purchased sitting in my garage, you can see how much room they take up.
I ended up buying three 6 ft fume hoods total, they just sort of fell in my lap. The two in that picture I paid $100 each for. matter of fact, the same place has 54 lab cabinets that they are selling for $100 each. I ended up picking up a lot of the cabinets myself, if anyone would like the contact information, it's in Union City Ca. I can hook you up with the person selling the cabinets
This is the fume hood I traded for:
That fume hood is only 4ft long. If you look in the picture, you will notice that it's next to a door. That is one of two garage doors, not counting the roll up door and door into the house. Normally you wouldn't want to put a fume hood right next to an exit, OSHA would have a field day with that. But since I have a door less than 20ft away I can use, it's within code. When I get a chance, when I'm back home, I'll take a picture of the fume hood, and scrubber together so you can get an idea of how much space they take up. It's right around 8ft in length and about 3 1/2 feet deep for the fume scrubber and fume hood.
I have a stainless steel table next to the fume hood, the scrubber sits under it. I bolted down a piece of polyethylene on top of the stainless steel and treated it so it wouldn't be slippery, that is where I have my reaction vessels set up. Because my reactions are contained within an enclosed system, I don't do my AR reactions under the hood. I use my hood for everything else though. It had an acid stainless steel vent with an 8 inch outlet that I changed to poly, I ordered the poly vent from US Plastics. I had to slim down the vent for my exhaust set up. The reason I put the fume scrubber next too the door was that the roll up garage door would have prevented my shroud from being all the way up. If I could, I wouldn't have it next to a door the way it is now.
So far as the cost involved in making my own fume scrubber, my first one was super cheap. I bought a poly chemical tank with a lid that screws on for my access, and enough room for the spray stack to be attached to. I paid $50 for the tank. The pump I bought new from US Plastics, it was right around $250, all said and done. The spray nozzle I already had, it was something I had purchased for a salt water tank that I adapted to use for this, but it's cost when I bought it was probably about $10 dollars. Since I made the eductor, I kept the price waaaay down. I think it ended up being $20 worth of materials, and I purchased them all from US Plastics, if you would like I can give you a list of the parts I used to make my eductor. The spray down stack was pipe I took out of the same place the fume hood came out of. The Re-Marketer I hooked up with allows me to go with him when he is bidding on a room, so I can remove equipment, pipe, or other things I can use. Otherwise 12' PVC pipe can be a bit expensive. I bought the bio balls I used for the spray down stack off eBay, I used new ones because any I have extra laying around have all kinds of growth on them from being in salt tank filters. Total cost of the bio balls might be $30. I also did another thing that wasn't in the original design, I put floating plastic balls in the tank. I read about the same type thing on US Plastics, but the balls were expensive so I found my own, the idea is that the balls cover the surface area of the water and by doing so force the water to retain the gasses longer than normally they might. It's used in industry, for the same reasons in open vat tanks. The total amount of materials I use to neutralize the minor nitric acid that can collect in this enclosed system was about $50.
It adds up fast, but you should be able to build your own fume scrubber, that works better than what you can buy on the market for 5 times as much. I was talking with an engineer for a company that also sells fume scrubbers, so I asked him about the type I was building, at the time. He only had to think a minute, then he told me that it was a smart way of doing it, and that it was probably, literally, the best design for my type of operation. He said brilliant more than a few times. 4Metals really outdid himself posting this design. Even with my home made eductor I am pulling 10cfm, actually a little more.
Oh yeah, I bought a plastic welder from Harbor Freight to put all the pieces together, and if you are interested, Harbor Freight has instructional video's on how to properly use a plastic welder, using the very model you purchase.
If you are smart, and you are willing to do a little hustling, you can do this for really cheap. I found a secondary supply of 12'' PVC for spray down stacks. I was driving by a city yard, I pulled over and walked into the yard. A bunch of guys were having lunch so I asked them if they had any scrap PVC underground water pipes, they had 12'' pipe, and just gave it to me. It's what I am using on my second scrubber I am putting together.
I am not replacing the first fume scrubber, I am making a totally new one for the assay lab I am putting together.
Have any questions, just ask, I probably said a lot more than you wanted to know. Post any questions here and I'll try to answer them if I can. You should know though that there are many people who have far more experience in all this than I do, that might know better. I answered because this is something fresh in my mind that I have been putting together for awhile now. It's easy to write about something you are currently doing.
And like always, if I said something that is wrong or incorrect, or misleading, please correct me
Scott