pressure causing leaks through flour paste

[joe951623]

just built a pot still with a bowl held on by binder clips, and all sealed up with flour paste, attached a 20' 3/8" worm.

when I run it for a 5+ minutes it will start leaking vapor around the flour seals, and it gets worse pretty quickly so patching doesn't help. I got some condensate through the worm but it seemed like a lot was being lost as vapor. I re sealed it but couldn't get it to stay without leaks, the vapor wets the paste and i get pinholes where it softens.

I realized I put a slight kink in worm right before it exits the bucket. I disconnected it to test and it still has enough clearance to blow through the tube, it's like breathing in through a cigarette or straw, and water from the sink flows through smoothly. I also noticed the soft copper tube bent under it's own weight so all the spirals don't sit flat, some have a slight angle up now so it catches liquid in the low part of each turn, and the vapor pressure has to push that around the next turn so it sputters a little.

should I let the flour paste dry more before turning on the heat or is there a way to make it seal better? or do I need a less restrictive worm?

[bellybuster]

fix your worm and all will be good. All needs to be downhill.

[Coyote]

That "slight kink" as you call it looks to be
about a 75% restriction - Not good.

How big is your boiler? Possible that your
boiler is so small that your heating things up
too fast for the flour paste seal to cook
thru and thru

Coyote

[sekked]

Hi Joe,

I had this problem on my first few runs. Now what i do is. I let my flour past dry out a good 30 minutes before turning on the heat.
Also, when i put on the heat I put it on very low so the heat from my burner and my pot dryes out the past even more.

My first coil was full of kinks and was sagging. so i welded a few copper pipes in my condensor bucket and welded the flexible copper pipes to it.

I included a picture. I made a better one since but it gives you an idea.

S.

[dirtymax731]

What they said^ fix that worm and maybe you are using to much water in your flour paste. When I used to use it would dry before the boiler got up to temp. And if it was a little wet itd just put some dry flour on it to dry it up. Just a thought

[sltm1]

You're lucky the seal doesn't hold...pressure in a pot still is a disaster waiting to happen!! Once you get the kink out of your worm, you might want to look up how to make a propper gasket out of cardboard and PTFE tape, but before using it, please make sure the backpressure is gone!! Happy stillin'

[joe951623]

Thanks for the replies! I'll make something to prop the worm up better. Didn't realize soft copper meant it would collapse under its own weight. It wasn't much pressure...i was getting bubbling through the flour paste where it was still damp.

I used a ptfe gasket to attach the column, its leaking around the lid/pot seal and the worm attachment

[T-Pee]

It wasn't much pressure...i was getting bubbling through the flour paste where it was still damp...its leaking around the lid/pot seal and the worm attachment

Any pressure or leaks is dangerous. That "steam" is highly volatile alky vapor escaping. Add any open flame and...

tp

[Coyote]

.5 to 1.5 PSI causes a bang like you can't believe
under the right set of circumstances.

Zero back pressure is what you need

Coyote

[cranky]

O.K. for my 2 cents, parts for a liebig (3/4" over 1/2") cost roughly the same as the coil in a bucket and a liebig has a lot of advantages over a coil anyway. #1 it is compact and easier to store. #2 you know it is always going down hill. #3 no restrictions to worry about and largely trouble free. #4 it is easy to clean, way more easy than a coil. There are a lot reasons more but those are the primary reasons. A cheap harbor freight fountain pump ( http://www.harborfreight.com/200-gph-mi ... yexnYVPMzQ" onclick="window.open(this.href);return false;" rel="nofollow ) and you don't waste any water. With 3/8ths tubing, even with a good unkinked coil, if you run it hard you may still build up pressure and have the blowout problem. Running slow might help but it could still be a problem. Lastly, try wrapping the edge of the lid with PTFE tape, (nice thick wrap, 5 wraps, maybe more) and the problem should go away as well as the mess.

[mmmmmm]

I do something similar to sekkid but without the welding. I'm running right now so I'll get the best pic I can.

The wire mesh is pretty rigid, I had to use a lot of force to bend it around circular, and then I wired it together. Then I made my worm around the outside of it, and wired it to the mesh all along the way, so that puppy's not going anywhere.

The wood on top, I cut to length to just fit inside my bucket, and hand-sawed some grooves in it so it would fit right down on top of the wire mesh column thing I'd made, then pressed it all down into the bucket hard and screwed the wood down on both sides right through the top/sides of the bucket. Sealed those holes with silicone, as well, obviously, as the hole where the worm comes out of the bottom of the bucket.

That wood screwed in there really holds the whole thing down and in place really well. I didn't want it wiggling around and messing with my silicone seal where it comes out the bottom, and I haven't had to reseal that silicone - ever. It's still the same silicone I put on something like 20 runs ago.

[Bugflipper]

On just the flour itself you should be thinking more of a putty than paste. It should form a ball easily. If the gap is a bit bigger than that can patch then mix some oatmeal in it. That will suck the moisture out quicker allowing it to set up faster. The patch should harden up before the vapor ever becomes an issue.

[rad14701]

I've used flour paste for decades with only two minor leaks in all that time... My current mix for my small scale rigs is 3 tbsp plain old white flour and 2 tbsp hot water and mixed till it gets elastic webs... I apply it to all components, fire the rig right up, and let the heat-up cure the paste to hard...

That 3/8" worm is on the small side to begin with and with a kink it can become even more problematic... It's either restricting the vapor flow or you are throwing too much at the boiler... Bump up to 1/2" and your troubles should disappear...

[FightnFive]

O.K. for my 2 cents, parts for a liebig (3/4" over 1/2") cost roughly the same as the coil in a bucket and a liebig has a lot of advantages over a coil anyway. #1 it is compact and easier to store. #2 you know it is always going down hill. #3 no restrictions to worry about and largely trouble free. #4 it is easy to clean, way more easy than a coil. There are a lot reasons more but those are the primary reasons.

+1 Yup, build a Liebig.