how to make a carbonator cap for a glass demijohn?

I have 5 very thick 1-gallon glass demijohn jugs that I use to ferment test batches. Now that I have a kegging system, I would like to make a carbonator cap so that I can carb the batch directly in the jug. Just 2 volumes of CO2 or enough to evaluate the recipe under carbonation. They come with twist-on metal caps, and only 2-3 threads engage to seal it against the rubber seal on the underside of the cap.

I have seem some plans using a tire inflator, but I'm looking for something that I could hookup to a quick disconnect and let it carbonate slowly in my kegerator.

first I would never try and carbonate in glass. second no reason to reinvent the wheel I would go with one of these I have two and they work wonderful. hope this helps

http://morebeer.com/view_product/18250/102290/Carbonator_Cap

twinfore said:

first I would never try and carbonate in glass. second no reason to reinvent the wheel I would go with one of these I have two and they work wonderful. hope this helps

http://morebeer.com/view_product/18250/102290/Carbonator_Cap

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I've already bottle-conditioned multiple times in these jugs, which is even more pressure than slow force-carbonating, so I'm not worried about them shattering.

It says it is a ball-lock fitting - I wonder if I could buy the fitting with a screw-on connection and install it in a metal cap?

I'd like to come up with a solution that costs significantly less than $16/cap.

This might be what you've seen http://www.crankandstein.net/index....s_id=4&zenid=0d394957af3108de32133346ae4f6088

They do make locking tire chucks that you could adapt, but that might leak.

You could also buy some spare caps, drill a hole in them and hook up a barb thought the cap and just run a co2 line straight into to jug.

zoso said:

This might be what you've seen http://www.crankandstein.net/index....s_id=4&zenid=0d394957af3108de32133346ae4f6088

They do make locking tire chucks that you could adapt, but that might leak.

You could also buy some spare caps, drill a hole in them and hook up a barb thought the cap and just run a co2 line straight into to jug.

Click to expand...

yeah, that's what I'm thinking of. Although I can't understand how they make a seal to the cap, and I would like something I can leave connected without holding the chuck in place.

What I'm picturing has to be a two-part, threaded fitting, with a gasket on the inner side of the bottle cap. Then when you thread the two pieces together, the gasket is pulled tight to make a seal against the cap, and the end projecting out fits a QD from a CO2 line.

Could I adapt a keg post to this application? Or do they need the threads in the keg lid to work?

I use a modified valve stem extension like a screw on chuck for my DIY carbonator caps & DIY mini keg Bung. My CO2 is supplied from a 16g cartridge for force carbing but I don't know why it wouldn't work for you to insert it in a 1/4"ID tube tied to your gas system.



The stem extensions have an inner gasket that seals when screwed onto the valve, seems like it should be able to hold 10-50 psi.

The other nice thing about a modified stem extension chuck is you can leave the schrader valve in the cap so when you remove from the gas, the thing self seals just like a tire.

Hope that makes sense...

oooh -this guy used a tire stem kit:
http://www.truetex.com/carbonation.htm

I bet I could use this to make the seal with the cap, then find an adapter fitting to connect to the gas line:
http://www.sjdiscounttools.com/mils409.html

I reeeealy don't know if carboys are engineered to hold any pressure. If pressurized a tiny tap with the wrong thing might make a heck of a mess.

twd000 said:

oooh -this guy used a tire stem kit:
http://www.truetex.com/carbonation.htm

I bet I could use this to make the seal with the cap, then find an adapter fitting to connect to the gas line:
http://www.sjdiscounttools.com/mils409.html

Click to expand...

Valve stem extension is threaded to fit right on the tire valve you linked. they cost ~$5 for 4 and fit snug in 1/4" ID line. Tire stems have an odd threading, from what ive read so your options are limited.

Do you have a manufacturer on those demi's?

starman said:

Valve stem extension is threaded to fit right on the tire valve you linked. they cost ~$5 for 4 and fit snug in 1/4" ID line. Tire stems have an odd threading, from what ive read so your options are limited.

Do you have a manufacturer on those demi's?

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yeah, I'll probably just have to take the tire stem into the hardware store and try some fittings.

The demijohns came from Sunflower Market and were once filled with apple juice