John Guest fitting Accuflex Bev Seal CO2 leak

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Active Member
Jan 23, 2014
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Hi guys,

I've recently had to setup a new keezer (US to Australia move) and as I'm connecting my gas lines I find that I can't get a leak proof seal on my John Guest MFL fittings with my Accuflex Bev Seal Ultra line. 4 out of 6 have tiny leaks. I've tried cutting the line again and re-sealing them multiple times, I've cleaned them, I've tried putting keg lube on the hose and o-ring.

They have been disconnected for about 6 months, could it just be an o-ring thing? I've ordered some new ones and am waiting for them to arrive.

Everything I can find to read about these fittings and the line says they are great but has anyone else experienced this or do you have any suggestions? Does anyone change the o-rings periodically? I'll wait for the o-rings but I'm ready to throw them in the trash!

I just undid the MFLs so all the connections and line are the same. I have a roll of line so I'll try some new line. It worked OK and I never noticed I lost CO2 but every now and the when I'd change a keg and dip a ball lock and MFL in star san the odd one would have a tiny leak. Mostly fixed by cutting the line and resealing.

The hose is rigid and the connectors seem unforgiving to angles and bends so I'd just expected to find lots of posts saying "don't use them for the gas side". I can't so am wondering if I'm doing something wrong.

The more I think about it the more I'm leaning to o-rings.
Yeah, don't use Bev Seal Ultra for gas line. Not sure why you are; it's stiffness will make it hard to get it to seal gas-tight.
Thanks, I don't know why I am either, it sucks. You're the first person on the internet who I've found say that but it confirms what I was thinking.

Is there any line for gas and John Guest fittings or are barbs best for CO2?
I wouldn't use John Guest fittings.

I used this tubing with flare firttings:

It's smaller in diameter, stays flexible in cold temperatures, and doesn't kink. It's a bit of a challenge to get it on 5/16 flare barbs but it won't leak. Used oetiker clamps on it to insure a leak free seal. Any metal-on-metal flare connections should get nylon flare washers to insure a leak free seal.

I have all my gas side connections set up as flare, makes it easy to change things around if needed.
Thanks for the information. I picked up some "official" John Guest tubing on the way home last night from the LHBS and it gives a gas tight fit into the MFL fitting where it was leaking with the Bev Seal but there is still a tiny leak somewhere. I have 16 of those fittings across 2 three way manifolds so there are plenty of opportunities to leak.

I'll isolate the tiny leak for the meantime with the John Guest line and fittings but I'll upgrade the whole gas side to barbs, clamps and polyurethane once I can order the bits in. I'm looking forward to gas line that is leak proof and flexible! Thanks for the help.
Go with the oetiker style clamps. They offer a superior seal compared to conventional screw-type clamps.

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