Fume hood made of polypropylene

[autumnwillow]

Hi,

I've been lurking the forums researching on how to make my fume hood first before proceeding with AR refining. Basically I just want to refine a maximum 50 oz per day. Then when I am able to make this setup work, I would probably create something bigger.
I do not have problems with the other equipments required except for the fume hood with wet scrubber.

Just a few questions if anybody could answer.

1) Why are most of the fume hoods here made of wood? I have found some polypropylene sheet (black polypropylene) supplier with 8.0 mm thickness, if i use these to make my fume hood will it be okay?

2) Why PVC tubes and not polypropylene tubes (PPR tubes)? Is there anything that I haven't read in these forums on why would PVC tubes would be better in the process?

3) Is it okay to use cylinders made of polypropylene (the one used in industrial water purifiers) as my wet scrubber? Polypropylene connected tubes with a bubbler at the bottom of each cylinder (i plan to use a fish tank bubbler to spread the gas further), 1st and 2nd cylinders will be a caustic solution and the last cylinder would have distilled water filled, sand, lime stones, bio balls and a mist eliminator on top.

4) I plan to use a vacuum pump at the end of the system but I need the hood to remain in a non-vacuum state. Will this setup work with a 9 cfm vacuum pump? If I use the air blower concept will there be bottleneck somewhere? Probably gas backfiring from my wet scrubbers?

5) Will a 3 feet cube fume box be enough for 50 oz refining? If not, what can a 3 feet cube fume box refine at most?

I know questions 3 & 4 are hard to understand, I'll try to draw a schematic diagram tomorrow.

I will share all my progress here with photos.

Thank you!

 

[Digitaria]

Hiya - Just wondering how you were getting on with your plans?

Probably most fume hoods are made of wood / ply because its easy to come by, sold in large sheets and easy to fabricate, whereas plastics can be pricey. I reckon 8 mm would probably be more than required from a structural perspective? Again, the same with pvc - its just easier to obtain.

I know only a bit about scrubbers, which I have learned from this forum and its members. 'Thanks guys.' So I may well get things wrong, but I would have thought that polypropylene if a thick wall cylinder would work but if thin walled, it could potential become hot exothermically and could fail, just use glass containers, its easier. As for the other questions, I suggest you follow up again, if you haven't already done so.

Lisa

 

[autumnwillow]

Yeah, I just found out that using polypropylene would be too expensive. I was thinking of having fabricated glass as my fume hood instead with wood as base. Maybe tempered glass? Not sure. But if pyrex (borosilcate glass) can withstand Aqua regia. I think tempered glass should work?

I will only use polypropylene tubes for the scrubber air ducts and sink piping. The problem here is how will I adhere the tubes to the glass hood.

I haven't really started with my fume hood because of work. I do have plenty of time now and I will be starting to ask a few local suppliers about glass fabrications.

Thank you for your input.

 

[Smack]

Forget tempered glass, anything that has to be custom made by someone else will be very expensive. But if your willing to spend that kind of money why not buy a real used fume hood off the internet.

 

[Lou]

I think polypropylene would be the cheapest, or HDPE. You can often buy large 1/2" X 48" X 96" sheets on ebay, and welding polypropylene isn't that hard.

Lou

 

[dannlee]

I'm not connected with these folks, just a studied link for my Airstream trailer rehab project.

http://www.thecuttingboardfactory.com/

They dropped having prices viewable, I thought they were reasonable when they did.

Check their cut-offs section (BLOWOUT SPECIAL) on this page...

WorkHorse Series Green Cutting Board - 3/4"x8"x18" = $12
PlayGround UV Board - Royal Blue - 3/4" x 12" x 48" = $40
PlayGround UV Board - Royal Blue - 1/4" x 14" x 48" = $12 ea
MarinaBoard UV - Seafoam - 1/2" x 4" x 48" = $7 ea
HDPE - Black - High Gloss Smooth 1/4" x 9 1/2" x 39" = $7 ea
HDPE - Black - High Gloss Smooth 1/4" x 9 1/2" x 60" = $12 ea
HDPE - Black - High Gloss Smooth 1/4" x 15" x 39" = $10 ea.

They have 0.030 and up roll stock of HDPE... 1/16, 3/32, 1/8 x 48 x 96 of Ultra High Molecular Weight Polyethylene (UHMW-PE).... The shipping prices go way down when they can roll the pieces for shipping. See http://tinyurl.com/ke3jxuk...

Would be a nice way to cobble together a spill & splatter proof fume hood, use the thin stuff as liners...

 

[Lou]

Yes, it is possible to wrap wood with the plastic.

 

[autumnwillow]

According to this: http://www.genpore.com/pdf/chemical_resistance_chart.pdf

It is not recommended to use hdpe or uhmw-pe. Why is that?

 

[justinhcase]

For my money a good marine or aeronautical Plywood is one of the wonder materials of our age.
The laminate being high grade Epoxy is very chemical resistant,while the fibers are some of the most robust and versatile known.
I do like my man made fibers and materials but find that things like plywood that use the best strength's of natural and man made materials are amazingly versatile.
I think that using a two part chemical resistant epoxy paint on ply will be much easier to construct and hard wearing bit of kit.
Even if you invest in a chemically resistant plastic sheet you will have to construct a rigid box from a material you can cut,drill,and screw.
Skimping on this material with some thing like M.D.F. will work in the short term but in the harsh lab environment will fall apart the first time it get's wet.
So I thought I would take a moment to extol the virtues of a very old friend that has made a good meany of my hair cap projects work.
the much abused and still dependable wonder wood is always my first go to material for most one off job's and prototypes.
p.s.
luckily I reigned my self in,I was about to go on about all the speakers,yachts,aircraft,home's, I had worked on that ply had been the only viable solution but realized that would be best on the Chippy's forum.