Teflon Tape for Gas Connections

[MaxM]

After hooking up my gas lines for the first time after moving, I lost what was left in my CO2 tank overnight. The only valves that were open were the main valve on the tank and the valve on the regulator, the latter I suspect as the leak. It looks to me like the connection between the gas line and the regulator is bare metal on metal which isn’t normally good. See attached photos.

Should there be Teflon tape on this connection? Is there normally an o-ring in there that I’ve lost?

I’ve dispensed out of the same setup for like 2 years, so maybe when I hooked it back up after the move, something went wrong. I’d do a leak test If I had any gas left...

Thanks for your input.

 

[IslandLizard]

Sorry to hear you lost your tank content.
No teflon tape on MFL (flare) connections. Metal on metal surfaces like those need a (fish eye) flare washer, like these:

http://www.ritebrew.com/product-p/843414.htm
Your homebrew store may have them too.
Most if not all plastic MFL QDs have a (plastic) washer built in the tippy, above the threads, they won't need one, generally.

Make sure there's no leak elsewhere.

 

[GoeHaarden]

No teflon tape on MFL (flare) connections

Just curious. Is teflon tape not needed with flare fittings, or will teflon actually increase the chance of a leak?

I've always used teflon tape on my connections, but I think I've developed a small leak. Recently used up a 10lb tank on 5x 5 gallon beers (closed transfer, carb'ing, dispensing) over about 3 months. I feel like I normal get more out of it..

 

[jmcquesten]

The Teflon isn't needed. I don't think it increases the chances of a leak if you have it on the threads, unless it keeps it from tightening down on the required plastic seal.

Just curious. Is teflon tape not needed with flare fittings, or will teflon actually increase the chance of a leak?

I've always used teflon tape on my connections, but I think I've developed a small leak. Recently used up a 10lb tank on 5x 5 gallon beers (closed transfer, carb'ing, dispensing) over about 3 months. I feel like I normal get more out of it..

 

[GoeHaarden]

The Teflon isn't needed. I don't think it increases the chances of a leak if you have it on the threads, unless it keeps it from tightening down on the required plastic seal.

Thanks. That's what I kind of thought, but wasn't 100% sure. Same question regarding the use of a flare washer & built-in washer on the disconnects? If you used a washer with those disconnects will it cause an issue?

I'm not 100% I have a leak but I feel like I usually get close to 10 beers with my tank...maybe a loose gas post!?

 

[IslandLizard]

Thanks. That's what I kind of thought, but wasn't 100% sure. Same question regarding the use of a flare washer & built-in washer on the disconnects? If you used a washer with those disconnects will it cause an issue?

I'm not 100% I have a leak but I feel like I usually get close to 10 beers with my tank...maybe a loose gas post!?

A flare washer on top of the QD tippy should not cause leaks, but now you have 2 surfaces that need to be sealed. If the QD tippy is not smooth, irregularities, a burr, a molding ridge, the plastic flare washer may not be able to seal that, while a stainless flare may.

Yeah, I would check around for leaks, that does seem quick. I've had one of those little red handle gas valves leak. Those should always be at 90° positions, never in between. Also QD poppets not quite sealing, and most of all, small leaks around the post o-rings.

Once lost almost a full 15# tank due to a loose MFL coupling I had forgotten to tighten up with a wrench.

1 pound of CO2 yields ~64 US gallons at atmospheric pressure (14.7 psi).
That's 32 gallons at 15psi (above atm. pressure) as read on your regulator.
Enough to liquid purge or dispense 32/5.5 = 5 kegs at that pressure (15 psi). Or 2.5 kegs doing both (liquid purge and dispense).
So 5 pounds should cover 5*2.5 = 12.5 kegs that way. 10 kegs easily, with 2.5 kegs worth (12 gallons at 15 psi) of other utility use.

 

[IslandLizard]

Ah, don't forget to check/tighten the screw lids in the top of the QDs. Or the skinny o-ring. I often hang all my QDs in a small bucket with Starsan. Dual purpose, sanitize and check for leaks.

 

[mulletmaster]

Yeah that will need a nylon seal or an o-ring if you are in a pinch. I just ran into this while setting up a manifold for the first time.

I hate how terrible the quality is for beer fittings. As someone who works in the aerospace industry, specifically hoses, that uses flared fitting every day the surface finish is garbage. Due to this the sealing faces, especially on softer metals such as brass, gets imperfections causing leaks so a seal is needed.

 

[IslandLizard]

Yeah that will need a nylon seal or an o-ring if you are in a pinch.

+1 on the o-ring when in a pinch.

 

[day_trippr]

[...]As someone who works in the aerospace industry, specifically hoses, that uses flared fitting every day the surface finish is garbage. Due to this the sealing faces, especially on softer metals such as brass, gets imperfections causing leaks so a seal is needed.

And those "aerospace-quality" fittings likely cost a few orders of magnitude more.
No thanks, what we use works just fine with proper - and quite simple - consideration...

Cheers!

 

[bleme]

The welding shop where I exchange tanks has all the hose fittings/seals/gaskets/rings.

 

[IslandLizard]

And those "aerospace-quality" fittings likely cost a few orders of magnitude more.
No thanks, what we use works just fine with proper - and quite simple - consideration...

Cheers!

Plus the cost of replacing them later, is well, astronomical!

 

[cswant88]

Teflon tape should only be used on NPT fittings where the tapered threads are what is forming the seal. Straight thread fittings do not needs teflon tape and are sealed with some sort of gasket/o-ring/washer. On the metal to metal flare fittings, you need the flare washers mentioned above. You shouldn't need them on the plastic QDs, as they have an integrated washer.

You can confirm that you have a leak by simply turning off the valve on the tank. Watch the gauges on your regulator, if you have a leak, the high pressure gauge will drop first, followed by the low pressure gauge. If the gauges stay put for a few minutes, you can be reasonably sure you don't have a leak.

Once you confirm you have a leak, you can hunt it down by isolating components. turn on the gas supply and repressurize the system. Close the shut-off valve on the regulator and turn the gas supply off again to leak test the regulator itself, then open the shut-off with the gas tubing disconnected from the keg to leak test the tubing and QD. If you determine the leak is somewhere in the keg, and you can't find it with the starsan method, start replacing o-rings starting with the gas post o-ring.

 

[chezhed]

Could the leak be your regulator connection to the tank?
Did you know there is yellow teflon tape and that is preferred for gas as opposed to white for liquid.........so I have been told

 

[bleme]

Could the leak be your regulator connection to the tank?
Did you know there is yellow teflon tape and that is preferred for gas as opposed to white for liquid.........so I have been told

I thought the yellow was just for propane, which can dissolve the white?

 

[mongoose33]

mulletmaster said: ↑
[...]As someone who works in the aerospace industry, specifically hoses, that uses flared fitting every day the surface finish is garbage. Due to this the sealing faces, especially on softer metals such as brass, gets imperfections causing leaks so a seal is needed.

Plus the cost of replacing them later, is well, astronomical!

You should be penalized 100 likes for that one.

 

[mongoose33]

As far as buying the swivel nut washer that @IslandLizard showed above, when you buy 'em, buy a half dozen. Unless, that is, you wish to expand your vocabulary the first time your only one slips through your fingers, bounces twice, and goes to an inaccessible place under your equipment or down the drain.

Don't ask me how I know this.....

 

[cswant88]

I thought the yellow was just for propane, which can dissolve the white?

I found this information. The person that posted this did not reference a source, so take it with a grain of salt.

The CURRENT standard is:

White = single density tape and is ONLY good for small fittings up to 3/8 in. pipe. Most people are unaware of this. "Double Density" tape used to come in white as well, but because that could be used for larger pipes, it was impossible for inspectors to know if the white tape used on 1/2" and larger pipe was in fact double density, so they stopped making it.

Yellow = double density, required for natural gas (methane) piping 1/2" to 2" dia. pipe. In many jurisdictions you MUST use double density tape on gas piping, so inspectors will look for yellow.

Pink = triple density, required for NPT threads 1/2" to 2". Again, most people are unaware of this change and hardware stores rarely sell it for the DIY market, but if you are going to get an inspection, this is what you must use now. This is also good for gasoline and propane lines.

There is also green for medical gasses (oil free tape) and gray / silver for use with stainless steel and aluminum pipe (has anti-seizing compounds embedded in the tape).

Over 2" you must use sealing compounds.

 

[IslandLizard]

You should be penalized 100 likes for that one.

I was thinking of the farsighted Hubble debacle.

 

[bracconiere]

tank washer? regulators can develop leaks too. just recently had replace my reg after 8-9 years of service....and i replace my tank washer after 2-3 swaps of the tank....

 

[GoeHaarden]

You can confirm that you have a leak by simply turning off the valve on the tank. Watch the gauges on your regulator, if you have a leak, the high pressure gauge will drop first, followed by the low pressure gauge. If the gauges stay put for a few minutes, you can be reasonably sure you don't have a leak.

Will the pressure gauges stay at pressure if there is no leak? How long? I just turned off the tank, and went back out (~30 min) to see that the tank pressure gauge was flat but the system gauge was still at my 12psi. Leak?

 

[bracconiere]

Will the pressure gauges stay at pressure if there is no leak? How long? I just turned off the tank, and went back out (~30 min) to see that the tank pressure gauge was flat but the system gauge was still at my 14psi. Leak?

yes...

 

[mulletmaster]

And those "aerospace-quality" fittings likely cost a few orders of magnitude more.
No thanks, what we use works just fine with proper - and quite simple - consideration...



Cheers!

Very true, fittings are not on the order of dollars, each just pointing out my observations and that all fittings are not created equal. It was a learning curve for me that I wanted to pass along.

 

[cswant88]

Will the pressure gauges stay at pressure if there is no leak? How long? I just turned off the tank, and went back out (~30 min) to see that the tank pressure gauge was flat but the system gauge was still at my 14psi. Leak?

Yeah sounds like you have a slow leak somewhere. Both gauges should stay put. Turn the gas back on to repressurize the system then start going down the line repeating the same procedure. Start with the shut-off closed to test the reg, then test your lines and QD detached from the keg. If the gauges stay put on those, your leak is at the keg.

30 min is more than long enough for this test. I usually wait about 5 minutes when leak checking my system. The high pressure gauge will drop pretty quickly.

I found this video helpful.

 

[GoeHaarden]

Yeah sounds like you have a slow leak somewhere. Both gauges should stay put. Turn the gas back on to repressurize the system then start going down the line repeating the same procedure. Start with the shut-off closed to test the reg, then test your lines and QD detached from the keg. If the gauges stay put on those, your leak is at the keg.

30 min is more than long enough for this test. I usually wait about 5 minutes when leak checking my system. The high pressure gauge will drop pretty quickly.

Thanks for the info. So I took off all the teflon tape and removed the washers. Afterwards, I re-pressurized my system and fooled around in the garage for a while and the tank pressure took easily 20 minutes before it started the fall. It's got to be a a very small, but costly, leak...

I feel like it's a keg, probably my RIS that has lasted longer than my normal brews for obvious reasons. Going to carry on with a stepwise leak test...

 

[GoeHaarden]

So, I turned off the regulator from the rest of the system and turned off the tank. After about ten minutes, the tank pressure gauge moved like 3 mm. Does that mean my regulator has a small leak?

 

[day_trippr]

Are you fully opening the cylinder valve? You should...

Cheers!

 

[mongoose33]

So, I turned off the regulator from the rest of the system and turned off the tank. After about ten minutes, the tank pressure gauge moved like 3 mm. Does that mean my regulator has a small leak?

It sounds like it to me. When you say you've turned it off from the rest of the system, how? If you have a shutoff valve, it's also possible it could be the source of the leak.

 

[jmcquesten]

Very true, fittings are not on the order of dollars, each just pointing out my observations and that all fittings are not created equal. It was a learning curve for me that I wanted to pass along.

I think some of the worst quality fittings are the shutoff/check valves a lot of people use in splitters or gas manifolds. I fought with a leak for over a year before finally tracking it down to those shutoff valves coming out of each regulator. I got rid of them and the leak went away. In my situation, they didn't really serve much purpose. I run a primary tank regulator to a (4) secondary regulator manifold straight to 4 kegs. If I need to shut off gas to one line, I can just back the pressure off on that secondary or disconnect from keg. I DID want the check valve function, so I found a deal on some higher quality check valves (without shutoff) and have them coming out of each secondary. I don't think they're "aerospace" quality, but they're not cheap, Chinese made fittings.

 

[GoeHaarden]

It sounds like it to me. When you say you've turned it off from the rest of the system, how? If you have a shutoff valve, it's also possible it could be the source of the leak.

So last night I turned the tank off and left it to see if the low pressure gauge would drop as well, and it did. So this morning (0700) I started from the top. I re-pressurized the system. Close the shut-off leaving the regulator and I closed the tank. I just check it now (0900) and the high pressure (tank) gauge is flat while my low pressure gauge actually increased 4 psi. Not sure what that is about!? I'm going to leave it as is today to see if it leaks out, and if it does it would mean that my regulator is leaking somewhere. Correct?

FWIW, I've soaked everything with soapy water and nothing....

 

[SEndorf]

Start with the shut-off closed to test the reg, then test your lines and QD detached from the keg. If the gauges stay put on those, your leak is at the keg.

This.
I'm hoping the OP is troubleshooting from disconnected kegs.
Once I blew a tank (rather quickly) due to a bad washer seat on the primary regulator at the tank.
The rest of my occasional bang-yer-head-against-the-wall, kick the cat, curse till yer blue in the face, extremely slow leaks have always been at the keg. On most of those very slow leaks, there are no visible star-san bubbles from spraying the tops.
The only way I can find it, is isolate each keg and turn the gas off at the secondary. Wait a half hour to hour, then turn the gas back on. If your gauge drops as it refills and you hear the infamous "gas groan", you've got a keg seal problem.

Once your gas lines and regulators are set up properly, I rarely find problems on the gas line side.

 

[S-Met]

As far as buying the swivel nut washer that @IslandLizard showed above, when you buy 'em, buy a half dozen. Unless, that is, you wish to expand your vocabulary the first time your only one slips through your fingers, bounces twice, and goes to an inaccessible place under your equipment or down the drain.

Don't ask me how I know this.....

No joke! I bought a dozen thinking they would last forever. I gave 6 to a friend and hae since bought another 2 dozen. I don't like being frivolously wasteful, but if I ever doubt their integrity, I toss them. Down the drain/disposal fish out and toss. Step on one on cement, toss.

 

[jmcquesten]

So last night I turned the tank off and left it to see if the low pressure gauge would drop as well, and it did. So this morning (0700) I started from the top. I re-pressurized the system. Close the shut-off leaving the regulator and I closed the tank. I just check it now (0900) and the high pressure (tank) gauge is flat while my low pressure gauge actually increased 4 psi. Not sure what that is about!? I'm going to leave it as is today to see if it leaks out, and if it does it would mean that my regulator is leaking somewhere. Correct?

FWIW, I've soaked everything with soapy water and nothing....

Or, it could be the shutoff valve. If you're talking about the little cheap Chinese made ball valve type shutoffs, that could be adding to the problem.

 

[GoeHaarden]

I think I found the culprit. My quad ring on the regulator has a small tear.

 

[mongoose33]

I think I found the culprit. My quad ring on the regulator has a small tear.

Thar she blows!

 

[chezhed]

I think I found the culprit. My quad ring on the regulator has a small tear.

bingo!!!!

Didn't someone suggest it might be the regulator to the keg connection.....

 

[GoeHaarden]

Didn't someone suggest it might be the regulator to the keg connection

I was still in denial that I even had a leak...lol Thanks! Got rid of all that Teflon tape though don't you worry..

 

[day_trippr]

[...]Didn't someone suggest it might be the regulator to the keg connection.....

Perhaps, but that's not where that damaged O-ring lives, so...

Cheers!

 

[cswant88]

All this talk of leaks made me go check mine. Sure enough, slow leak at the QD/gas post connection. Little keg lube and a squirt of starsan cleared it up.

This happens to me from time to time. Sometimes just popping off the QD and putting it back on takes care of it. I think the burna-n hardens a bit in the cold and sometimes compromises the seal. I switched to a silicone o-ring on the gas post because they stay softer but the darn things shred taking the QD off and on just a few times, even with liberal keg lube, so I switched back.

Anyone else deal with this?

 

[Soulshine2]

Could the leak be your regulator connection to the tank?
Did you know there is yellow teflon tape and that is preferred for gas as opposed to white for liquid.........so I have been told

that is correct. white for water , yellow for (natural) gas. I made sure to read all the comments up to you to make sure someone covered it already.