Chemical resistant sealer

[skyline27]

I'm building an aerated AP reaction bucket with an attached fume cleaning column.

Can someone recommend a sealing/caulking material that will not be affected by acid? Also, where can I find a clear cylinder to use as the column?

I want to have an air intake tube on the reaction bucket lid that will run to the bottom of the bucket. Another tube will run from the reaction bucket lid into the column top to the column floor. A vacuum pump will pull air through the column and aerate the reaction bucket. I'm not sure if this makes sense, it's hard to describe.

 

[Lou]

Teflon tape is useful.


Some Dow Corning silicone greases are very chemical resistant.

There are also fluoromer greases from Dow that work well too.

 

[Irons]

I'm building an aerated AP reaction bucket with an attached fume cleaning column.

Can someone recommend a sealing/caulking material that will not be affected by acid? Also, where can I find a clear cylinder to use as the column?

I want to have an air intake tube on the reaction bucket lid that will run to the bottom of the bucket. Another tube will run from the reaction bucket lid into the column top to the column floor. A vacuum pump will pull air through the column and aerate the reaction bucket. I'm not sure if this makes sense, it's hard to describe.

I hope that vacuum pump is resistant to chemical attack, otherwise it will quickly turn into a hunk of scrap.
I agree with Lou on the Silicone grease. I have a tube of it that I use for the ground glass fittings on my lab ware and it works very well. One tube will last a lifetime.

PETE is the only clear plastic that will resist Chlorine and won't cost you a fortune. Polycarbonate will work but is quite expensive. Acrylic is available in large tubular castings but the lifetime will be very limited.
You can buy Borosilicate glass pipe with ground fittings. New they are very expensive, but you might find some at a surplus outfit.

 

[skyline27]

Everything is setup, all I need is the right pump. Rather than a vacuum pump at the end of the fume column, I put an air pump blowing into the air intake. The AP gets aerated and the fumes are pushed out through the column.

I bought a cheap Coleman air-mattress pump that is way to strong and LOUD. Can anyone recommend a reasonably priced variable air pump? I tried an aquarium bubbler but it wasn't strong enough.

Also, what should I use to neutralize the fumes?

I can't wait to fire this up on the weekend. These fingers don't stand a chance!

 

[OMG]

You can get different sizes of aquarium bubblers, maybe you just have a low powered one. Then you can get a little inline cheap valve thing that you just turn to regulate how much air gets pumped through.

I have a water pump that is almost all plastic and rubber that I am going to use to filter dissolved metal/metal precipitates in my setup. I will have to replace a couple of plates and seals in the pump first though.
So, thanks for the great idea of using teflon tape Lou.

Anyone know how to distinguish PFTE from other plastics? Does is have a certain number in the recycling mark?

And also.. Does anyone know if there is any kind of good spray (paint) that can be applied to surfaces so they will resist corrosion from liquids or gas. (for a while at least)

As a side note. I have been using just plain silicon sealant (kitchen/bathroom stuff) and haven't notice it degrade. I used it to plug the hole in the bottom of a flower pot for a electrolysis experiments, and its sat in acid for probably a month in one stint and I haven't notice it degrade at all.

I'll post if I find anything useful.

 

[Lou]

This is a pretty good thread to mention this: a good pump is nice to have. This one isn't cheap, but it's very useful:

http://www.wildenpump.com/catalog/product-detail.cfm?pid=188

I have a similar Welden P025 pump, just my pump is 'pimped'. Its internals are all made of PTFE or coated with it (diaphragm, heads, chambers). It is pneumatic and runs off of compressed air. With one you can pull a decent vacuum, pump corrosives like sulfuric acid, HF, aqua regia, compress corrosive gases like chlorine and all at a nice range of temperatures and flow rates!


All you need is an air compressor and regulator for the air.

It's really nice if you do anything in bulk because you can drain out your reaction vessel with the pump. Very useful for converter work where you need to move large volumes of solution decently quick. Also nice for filtering stuff and not worrying about over flow into the vacuum line. Couple this pump with another vacuum pump (like a KNF Neuberger) and you can do many other nice things with it (like vacuum concentrate your solutions).

Generally speaking, PTFE isn't recycled. It lasts for darn near forever, and it's not very melt-able, and certainly not burnable!

 

[lazersteve]

Sky,

Lowes has a nice selection of in ground pumps, marine pump, bilge pumps etc. You may find something useful there. You can always run a long tube to your reaction bucket and keep the pump away from the reaction so it doesn't make you go deaf.

I just bought an electric vaccum pump from a dentist and it has graphite insides. I wonder if I can get the parts machined out of PTFE and change out the graphite pieces. I have to admit it has held up very well to everything I've vaccumed thru it to date (chlorine gas, HCl-Cl, HCl, AR, and ammonia. I've had to clean it and lubricate it with safety solvent twice in the last two months.

Steve

 

[Lou]

Graphite, like PTFE, should be self-lubricating?

Steve, you should be able to find some one that can machine some PTFE into pieces suitable for your pump. It might not be that cheap though, I'd be astonished if you could get it done for less than 400 dollars.

 

[skyline27]

I found the right pump. It's an Aquatic Gardens HI-Tech 7500 from Petsmart. It's quiet and you can adjust the power. The last hurdle is mixing up some solution to neutralize the fumes.

What readily available material will neutralize AP fumes?

 

[Anonymous]

if you want to pull the air through you can build a vacum pump using a
ventury, it also would work off of compressed air and could be made using pvc parts fairly easily

 

[lazersteve]

Lou,

The label on the vaccum pump states to clean by flushing with safety solvent, I assumed this was for lubrication, but it may just be to clean out the gunk every once in a while.

Steve

 

[GeeDub]

PETE is the only clear plastic that will resist Chlorine and won't cost you a fortune.

To paraphrase Bill Clinton; it depends on what the definition of "clear" is.
Crystal clear? Or just, "I can see what's inside" clear? Natural Polypropylene and polyethylene resist Chlorine. PP takes the higher heat.

 

[GeeDub]

I'm building an aerated AP reaction bucket with an attached fume cleaning column.

Why use a column?
I used old acid bottles filled with various bases; Lye, Sodium carbonate or Bicarbonate , Ammonia (as the next to last bottle) and plain water. The ammonia let me know when the bases needed recharging by the production of white smoke (which the water bottle caught).
I put rubber stoppers in each bottle. Made 2 holes in each stopper, and looped flexible polyethylene tubing from one to the other. The inlet tube would reach through the liquid to the bottom of the bottle, and the outlet tube about an inch into the bottle (above any liquid). Hooked the vacuum pump up directly to the water bottle outlet tube. Since no corrosive ever made it to the pump, there was no damage. Just had to remember to disconnect the pump after use and run for a couple of minutes to remove water vapor which could rust the chambers. My vacuum pump had replaceable carbon vanes that created the vacuum, so if I forgot, I could easily and cheaply rebuild the pump.

Oops; Gotta edit.
I first used polyethylene tubing. I soon after switched to clear braid reinforced PVC tubing. (it will turn milky white during use, but don't worry, it won't burst.
Sorry, it was 30 years ago. As I grew I moved on to better materials.
Although it can be scaled up to 55 gallon barrels and a shop vac for vacuum (needs air relief inlet), this idea is really targeted to the hobbyist or small shop processing less than 25 oz. karat gold at a time.
-G