DIY CO2 - better design?

I'm not quite ready to take the plunge and get a CO2 canister and the full nine yards, so I'm stuck with DIY for a while. Problem is, silicone does not stick well to polypropylene so the standard 2L coke bottle design is prone to leakages. I've found that all my sealed caps start leaking eventually and I keep a ready supply of sealed caps ready in case of failure.

Has anyone found a better way of sealing the caps or a different design altogether?

 

The best for me was to drill a small hole in the cap (smaller than the tubing)
Then you should cut the tubing 45 degrees so that the end is sharp, use pliers to pull them through the cap. That should be air tight!

 

+1 on what Pikkie said. I used a bit of marine silicone where the tubing entered the cap to make doubly sure that CO2 wasn't escaping....

Another option is the end fitting of a drip, that's what Abraham uses

 

@Pikkie - Did you also use silicone, or just leave it as is?

 

hi my way is a no silicone way
o ring and a flat waser i got from bilders wearhouse and then same as pikkie but ad a pease of hard air pype to wege it in there

 

@wolf - is the washer to seal the cap on the inside where it closes onto the plastic bottle edge? Did you remove the rubber seal that came with the bottle cap?

 

Never used silicone... The seal from a coke bottle is already airtight there's no need for o rings and stuff. Just pulled it through and it was fine. Any glue will also come off eventually.

 

So you just kept the standard seal and made a hole through that as well?

 

Yes exactly!

 

Cool, gonna try this tonight

 

If you dip the tubing in boiling water b4 you pull it back through the cap it's easier to get it in as the tubing is soft

 

I used the in-line barbed connector for 5mm irrigation tubing, ie the one to connect two tubes together. I had a couple lying around, but most gardening or hardware stores have them.

First, I cut/filed the barbs on both ends off. Once done, the connector fits standard airline tubing perfectly.
Then I drilled a hole through the coke bottle cap which was slightly smaller than the diameter of the connector (4.5mm drill bit?) and forced one end of the connector through the top of the cap.
Lastly, I used glue to fix and seal it permanently, but it was pretty airtight without.

Advantage of this method is that it is leak free and makes changing airline tubing (when it degrades) a much easier.

David

 

Another option is to make a hole in the coke bottle (not the lid). Then you just jam the airline in there and put some prestikk all around it. It's rather ghetto, but it works.

 

Thanks for all the tips, guys! I tried making a smaller hole than the tubing and just pulled it through, no silicone. I'm actually surprised it works! Wish I'd done this from the start!

@ Ryan - actually found some prestick last night and tried it, but it wasn't necessary. Gonna keep some handy in case of leaks, I'm sure it actually works better than silicone!

 

Hi Guys
Haven't been online for a while.

I use an standard syringe needle. the thickest one. It has a pink plastic connection for the syringe.

I file or cut off the "wings on the end of the plastic end piece - put the airline tube over it and just push the needle through the coke bottle top. perfect seal just like going into a vein..

enjoy