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Need a couple of stoppers for 20 liter flask

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rusty

Well-known member
Joined
Sep 15, 2010
Messages
1,782
I could use a couple of stoppers, hole in center or not. The opening on my flask is 62 MM / 2.441 Inch.

Best Regards
Rusty
 
what do they need to be made out of?

The brew store has them by my house. made out of rubber they will be cheep, but PTFE they will be expensive.

Eric
 
etack said:
what do they need to be made out of?

The brew store has them by my house. made out of rubber they will be cheep, but PTFE they will be expensive.

Eric

Either compound will do, I don't think a couple of PTFE stoppers are going to break the bank.

Our local wine shop only has 2 inch and his next order is months away, help - I'm desperate.

If someone can do this for me, I could use another couple of stoppers form my 4 liter filter flask, I do not mind paying for quality.
 
Here's a tip - don't make the plug solid if you expect there to be any temperature variation. The thermal expansion of the plastic will break the neck after only modest heating. The first plug I made, I made solid and it split the neck of a a flask before it ever hit 50 C! The trick to avoiding this is to hollow out the plastic plug enough so that the plug is able to deform ever so slightly under the heat. After spending time at higher temperatures the deformation becomes noticeable on disassembly as the teflon doesn't have a 'memory' like other plastics.
 
skippy said:
Here's a tip - don't make the plug solid if you expect there to be any temperature variation. The thermal expansion of the plastic will break the neck after only modest heating. The first plug I made, I made solid and it split the neck of a a flask before it ever hit 50 C! The trick to avoiding this is to hollow out the plastic plug enough so that the plug is able to deform ever so slightly under the heat. After spending time at higher temperatures the deformation becomes noticeable on disassembly as the teflon doesn't have a 'memory' like other plastics.

Never thought of that it says that it expands 0.136mm per deg C (seems like a lot). mine did have two holes in it and was much smaller, plus it was just a close fit and a few wraps of teflon tape.
 
skippy said:
Here's a tip - don't make the plug solid if you expect there to be any temperature variation. The thermal expansion of the plastic will break the neck after only modest heating. The first plug I made, I made solid and it split the neck of a a flask before it ever hit 50 C! The trick to avoiding this is to hollow out the plastic plug enough so that the plug is able to deform ever so slightly under the heat. After spending time at higher temperatures the deformation becomes noticeable on disassembly as the teflon doesn't have a 'memory' like other plastics.

Thanks skippy, I was going to turn one from wood, I'll order what I need Monday from Pegasus Glass in Ontario.

Another idea would be to cut off some heavy tractor tire lugs then shape to fit.

That 20 liter flask cost to much to be careless.
 
skippy said:
Here's a tip - don't make the plug solid if you expect there to be any temperature variation. The thermal expansion of the plastic will break the neck after only modest heating. The first plug I made, I made solid and it split the neck of a a flask before it ever hit 50 C! The trick to avoiding this is to hollow out the plastic plug enough so that the plug is able to deform ever so slightly under the heat. After spending time at higher temperatures the deformation becomes noticeable on disassembly as the teflon doesn't have a 'memory' like other plastics.

The guy I spoke with from Chemglass says PTFE is good at 212 degrees Fahrenheit, it is true though they have been known to crack your flask at elevated temperatures.
 
That's a good way of explaining it qst40now. Even hollowed out the stopper gets very tight when the flask is warmed and won't come out until the setup is cool again. I would never use a solid ptfe stopper unless I was only going to use it at ambient temperatures.
 
I make custom stoppers from HDPE or PTFE film filled with Silicone Sealant. They're not pretty but work great. It can be as simple as a baggie in the neck of the flask, pumped full of Silicone. Too bad they don't make Condoms out of PTFE. Talk about Fallout.. :mrgreen:
 
I wonder how long a 2.4" slug of silicone would take to cure through while you watch?

I know real fast in the tube before you get a chance to use it is common. :lol:
 
qst42know said:
I wonder how long a 2.4" slug of silicone would take to cure through while you watch?

I know real fast in the tube before you get a chance to use it is common. :lol:

Dow and other companies make a number of two component Silicones, some of which can cure quite fast. They're a bit pricey, but for making molds and custom parts for prototypes, they can't be beat.

Look up Silicone Mold on Youtube for dozens of videos.
 
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