Gas died again, and I have a new dilemma

[ScrewyBrewer]

My thoughts are that compressed gas is in a liquid state, which logically weighs the same whether it's warm or cold.

It seems logical that the pressure of the gas is lower when it's colder, that's why the gauge reads lower when the Co2 tank is stored in the refrigerator.

I'm having a hard time with this guy saying in effect that colder compressed gas, which is a liquid by the way, weighs different than warmer compressed gas which is also a liquid. Especially when the weight is off by 2 pounds or 40%!

[FedoraDave]

Oh yes...

PTFE Tape (or Teflon Tape) is to be used on water pipes in lieu of pipe dope.

It is not rated for gas connections and especially not for flameable gasses such as Propane or NG.

Also, any type of flange fitting or fitting with a compression washer or internal rubber washer should not require PTFE tape (so the output of closet valves, input of faucets etc.)

This makes me think that A) I need to quit using Teflon tape and just make sure I tighten the connection well, B) the replacement nylon washer I just got from the LHBS is not the correct piece, and C) some other part of the regulator needs to be tightened.

Again, I'm taking this to my LHBS for advice, and to have them re-evaluate the washer they sold me.

I'm thinking it's probably one of the other connections on the regulator, since I've had tanks crap out on me earlier than expected before I got this new washer. Still, checking out every possibility is the prudent thing to do.

[BlackDuck]

So here is a shot of my set up. If you look close enough, there is Teflon tape on the "wye" adapter and the pieces that connect to it. There is also Teflon tape on the gas line on the left. There is NO tape between the regulator and the cylinder. This is how it came set up from Kegconnections.

For the guys saying not to use Teflon....is this incorrect?



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[alb]

I'm not sure. My manifold looks like that at the top but it's not teflon tape, it's more like a white silicone caulk, all sealed up. But at the tank and in the MFL fittings there is not a hint of Teflon tape or pipe dope.

[Inkleg]

I'm here to tell you if it is NPT(National Pipe Thread) it needs pipe dope or teflon tape. Two quick reasons, one metal well not completely seal against metal without excessive tightening, it will leak without a sealant of some kind, two it acts as a lubricant to help protect against galling, especially true with stainless steel. The fitting from the regulator to the tank is sealed with a o-ring or nylon washer depending on set up, no dope or tape needed, but NPT, tape it.

[BigPapaG]

So Chris,

The wye adapter, the block on the regulator and the one way valves that thread into the wye are mpt/fpt connections (male pipe thread / female pipe thread, also known as NPT) and are not considered flanged or compression fittings.

In non-flameable gas situations like this, since the threads are like water pipe and the gas is inert, the tape can be used.

Just remember that the tape has a slippery quality and as such, the connection can rotate easily enough, breaking the seal.

EDIT: RectorSeal makes a Food Grade Pipe Dope that could be used instead, although standard plumbers pipe dope could be used if applied in such a way as to not come in contact with the flow of gas. (Ie: use a little and keep it high on the threads as opposed to the end of the thread.)

[BigPapaG]

@Jeff
Beat me to it!

@ Amy
Yours probably has the food grade pipe dope on the connections.

[BlackDuck]

Thanks all. I kind of figured it was similar to water piping and needed the tape. And I also figured that since it came pre-assembled from Kegconnections with the tape already on it, that it was how it should be. It's served me well with no leaks, so I'm not touching it.

[alb]

@ Amy
Yours probably has the food grade pipe dope on the connections.

That would make sense. And I forgot to say that my MFL fittings have little plastic tapered washers in them.

[BlackDuck]

Yes...I have those washers too alb!!!

[FedoraDave]

So I'm thinking I may have to dis-assemble the whole shebang and re-assemble it again, just to make sure things haven't slipped from handling, and to put Teflon tape on the connectors to the gauges and the out line.

[BlackDuck]

put Teflon tape on the connectors to the gauges and the out line.

Dave....just to clarify something. On my setup, I do not have Teflon tape on the threads that connect the red gas lines to the shut-off/check valves on the regulator. Instead, there is a small washer that fits inside the nut.

Here is the complete kit from kegconnection.com

I have only four connections that have teflon tape. I edited my previous picture with arrows that point to each of these four connections.

regulator.jpg (81.58 KiB) Viewed 2108 times

[alb]

put Teflon tape on the connectors to the gauges and the out line.

Dave....just to clarify something. On my setup, I do not have Teflon tape on the threads that connect the red gas lines to the shut-off/check valves on the regulator. Instead, there is a small washer that fits inside the nut.

Here is the complete kit from kegconnection.com

I have only four connections that have teflon tape. I edited my previous picture with arrows that point to each of these four connections.

regulator.jpg

Yeah. That.

[ScrewyBrewer]

I was told by the gas guys not to put teflon tape on the tank valve, or if I did to remove it with a wire brush before returning it to them.

beer-gun-3sml.jpg (51.15 KiB) Viewed 2104 times

But for the other threaded connections, I do tape them all.

[Inkleg]

Chris, you should have tape on the 3 gauges, the pipe connection to the first regulator and the short pipe connecting the two regulators also.