# Beer Gas Tank Full Pressure and Questions About Vinyl v. EVAbarrier Gas Tubes

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#### Clint Yeastwood

##### Supporting Member
HBT Supporter
I couldn't find a consistent or even roughly correct answer to this question on the web, so I got it somewhere else, namely a guy at American Welding Gas in Orlando. Maybe it will be useful to other people. Today he told me the pressure in a brand-new tank of beer gas should be around 1800 psi. That's at something like 75 Fahrenheit, and it will vary with the volume of the tank. For example, some 5-pound tanks are not the same size as others. Today I swapped an empty for a full aluminum tank, and when I got about a quarter of a mile away from the gas place, I turned back, because I realized the new tank was about 2" taller and might not fit my keezer. I swapped for a smaller steel tank. I'm going to measure my keezer next time.

A full tank will probably not come in at exactly 1800, but presumably, it won't be something grossly different, like 1500 or 2500, unless you have a pretty weird tank. The gas dude said "1800 to 2000." I saw what appeared to be at least three different sizes today, and they were all 5-pound tanks.

In case you're wondering what the pressure will be once the tank is in your keezer, chilled, unless the Ideal Gas Law has been repealed or amended, an 1800-psi tank will drop around 6.5% at 38. That's close to 1700. You don't need to know the whole law. You just need to know P/T = P/T for a constant volume and amount of gas. Convert the temperature to Kelvins. If you want to be really accurate, which serves no purpose in this case except to be annoying (1800/14.7 = 0.00816), add atmospheric pressure to the pressure on the gauge as a tiny, meaningless correction. If P2 is your pressure after a temperature change, P2= P1T2/T1.

I believe this is right. Check and see. I made a mistake once in 1973. It could happen again.

Now here is a question: is the EVAbarrier/Duotight system a good idea for beer gas, which often has to hold 35 psi? Duotight connectors are junk. Let's face it. They're very weak. They seem to work great for CO2 and beer, but I seem to be losing beer gas in a hurry. I blew through 5 pounds in a month, which is why I went to AWG today.

The directions for Duotight female threaded connectors say to adjust them finger-tight plus 90 degrees. This doesn't even work for CO2. Not even close. I had to use a wrench, and I went several threads past finger-tight. Now my CO2 system has zero leaks. It only has Duotight past the secondary regulator, though, so the pressure is low except when I'm carbonating a keg. I still have vinyl from the primary regulator to the secondary.

I redid the fittings and tubing on my beer gas system, and I'm under 800 pounds already. I tried them with and without nylon gaskets, and I found that with gaskets, you get so little thread engagement, the Duotights tear up when you try to tighten them properly. Then they have to be thrown out. Maybe I did something wrong and someone will want to chime in. I ended up applying keg lube to the threads and installing the fittings the same way I installed them on the CO2 system. No gaskets.

Should I go back to vinyl and barbs on the high side or what? I have EVAbarrier on the "out" side of my CO2 system, and it's fine, but I left vinyl on the "in" side because it took forever to get fittings and it was a real pain to change the "in" barb on my secondary regulator. I find vinyl or Tigan or whatever it is more flexible than EVAbarrier, and at 30 psi, it's not leaking at all. On the beer gas side, EVAbarrier and Duotight seem to be leaking at 35 psi, which is roughly the same as 30 and shouldn't be more of a challenge.

I pushed the EVAbarrier in all the way. I used EVAbarrier with clean ends. I don't know what could be wrong. I just made sure the cap on the Duotight gas disconnect on the keg was cranked all the way down. I suppose the keg could be leaking. It's a brand-new Torpedo keg, and I tightened the posts and seated the lid as well as I could. I have hosed it with Star San solution, and I haven't seen any bubbles. I have three crummy old kegs on the CO2 side, same disconnects, two old lid O-rings, and no leaks.

I put a steel valve compatible with Duotight on my beer gas regulator because old-style valves appear to be prone to failure. I am wondering if there is some kind of brass non-junk fitting that will connect this threaded valve to EVAbarrier or vinyl.

I'm inclined to think vinyl is superior for this purpose. Stiff hoses push the tanks around, and vinyl doesn't. Fittings that go with vinyl are metal, not plastic. The valves seem to be a weak point, but surely there is a fitting out there that will allow me to use the newer valves to connect to vinyl.

#### day_trippr

##### The Central Scruuuutinizer
Maybe you are looking in the wrong places for a leak?

fwiw, for my beer gas setup I have a "10 pound" steel cylinder with a cga580 valve and a Micromatic primary reg with their infamous 3/8" barb to which I managed to get 5mm ID EVAbarrier tubing over using a heat gun and swaging spike. At the other end of that tubing I have a Duotight 8mm tubing to 1/4" FFL PTC to a ball lock gas QD with 1/4" MFL stem that plugs on to a gas post at the back of my keezer screwed on to a 1/4" MFL-MFL bulkhead with an intervening adapter. On the other side of the bulkhead is a JohnGuest 1/4" FFL to 8mm tubing PTC with about 5 feet of EVAbarrier 5mm ID tubing to another JohnGuest PTC to a gas QD. There are no fisheye flare gaskets involved anywhere.

It sure seems involved but if I drew it out it'd look pretty basic - heck, there's not even a manifold involved, unlike my CO2 feeds into the keezer. Anyway, with all of that, I haven't refilled that cylinder in almost three years yet I have kept batches of an imperial chocolate stout continuously on tap the whole time...

Cheers!

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#### Clint Yeastwood

##### Supporting Member
HBT Supporter
The only thing I can think of to do is to lower the tank, tubing, and disconnects in to the pool while holding the gauges above the water.

I looked for brass push-to-connect fittings, but so far, I have not been able to find anything that will connect 8mm EVAbarrier to a 1/4" male flare fitting. You would think brass would be out there somewhere. There are plenty of other brass PTC fittings on the market.

Duotight gas disconnects must be okay, since they work for CO2, so I don't think there is a problem on that end.

The regulator is 20 years old, but it was only used for about 5 before I resurrected it. I put new gauges on it. I don't think they could be leaking. They're in there pretty good, with tape. The O-ring on the regulator looks great, and I lubed it before I installed the tank.

#### day_trippr

##### The Central Scruuuutinizer
I once found the tiniest leak at the base of a threaded-in PRV valve on one of my primary CO2 regulators. Just had to remove and regunk the PRV and it's been perfect every since. That leak had bugged me for a long time because it was so small it was hard to tell during isolation tests that anything had changed. I suspected everything but the PRV...

Cheers!

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#### Clint Yeastwood

##### Supporting Member
HBT Supporter
I got fed up and put the works in the pool, except for the body and gauges. I included the keg.

I got slow bubbles from the regulator valve-Duotight joint.

This thing was already tightened as much as I dared. I had destroyed two others trying to get one more half-turn on them. I cranked this one down anyway. I think the leak is gone. I couldn't get more bubbles from it.

It would be so nice to have real brass connectors that don't strip out.

I can't find any keg leaks at 30 psi. Can I be sure the keg never leaked? No. I resealed it last night. My precious stout is about gone, so I didn't care about opening and resealing it. Too late to worry about O2 and infection.

I've seen people claiming the real reason for EVAbarrier is oxygen intrusion. They say it goes through vinyl over time. I have to wonder if it's a real problem. I had a strong ale hooked up for many months without problems. Someone should poke the guy at Brulosophy. "I used vinyl on this beer and EVAbarrier on an identical beer..."

I guess I should set a spray bottle aside for soapy water and test every keg as I put it in the keezer.

#### beren

##### Well-Known Member
Ever think it’s the regulator side connection not the Duotight?
Use a flare washer maybe with it even though it’s plastic already. I have no issues with beergas and Duotight. Also my primary pressure goes off the scale on my 2k psi gauge. Co2 is like 1800 psi n2 is higher. N2 is 2200-2400 TIP: NITROGEN TANK AND GAUGE PRECAUTIONS | HVAC Know It All

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#### Clint Yeastwood

##### Supporting Member
HBT Supporter
You can't use a nylon washer with a Duotight flare fitting. I tried it. Maybe if you can find a way to force the washer all the way in before you screw the fitting on, but when you try to push one, it will do its best to open up and let the push tool through. The washer will sit inside the fitting and prevent you from getting enough threads on the male fitting, so when you turn it, the female threads strip.

I eventually found a leak at the base of one of my gauges.

After all this, I learned that the regulator diaphragm was bad and can't be replaced because it's discontinued. I'm installing a new regulator today.

#### Yesfan

##### Supporting Member
HBT Supporter
...........I've seen people claiming the real reason for EVAbarrier is oxygen intrusion. They say it goes through vinyl over time. I have to wonder if it's a real problem. I had a strong ale hooked up for many months without problems. Someone should poke the guy at Brulosophy. "I used vinyl on this beer and EVAbarrier on an identical beer........."

I'm one of those people. At the time I was switching over to Duotight/EVA Barrier, I had just kegged a 10 gallon batch of pale ale (2 five gallon corny kegs). One keg had the regular vinyl line (either Bevflex 200 or the Silver Ultra Barrier stuff, can't remember) and EVA barrier on the other line.

If you're one who flushes a bit of beer out of the line before pulling a pint (which I would do), you might not be able to tell the difference between the two. But go a full day, and not flush the vinyl line when you pull a pint, and it's a night and day difference. Now, I have the EVA stuff on everything. I'm a convert, plus there's too many positives to list for not switching over. The line is cheap, the fittings are cheap, you don't need 10ft of beer line to balance the pressure if you're using the 4mm ID line, etc.

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#### Clint Yeastwood

##### Supporting Member
HBT Supporter
Thanks, but I was writing about the gas line, not the liquid line.

#### Yesfan

##### Supporting Member
HBT Supporter
I can't tell you on that, but since I already had done the beer lines, I went ahead and done the gas as well. I figured it's easier if everything is kept the same.

#### day_trippr

##### The Central Scruuuutinizer
Gotta do both beer and gas imo...

Cheers!

#### mac_1103

##### Well-Known Member
Gotta do both beer and gas imo...
I've become convinced that the physics is the same, but the difference between immediately oxidizing the beer in the liquid line and very slowly increasing the dissolved O2 in the keg seems pretty important. Guess it depends on how long it takes you to drink the keg.

#### day_trippr

##### The Central Scruuuutinizer
My post-pandemic guest visits are still well below 2018 so kegs don't zoom outtahere like they used to
But I still enjoy brewing, so anything I can do to extend shelf life matters more than ever...

Cheers!

#### jddevinn

##### Got 99 Problems but beer ain't one
I had a lot of problems with the duo fittings years ago and ended up using a swagging tool with some boiling water for heat to stretch the EVAbarrier slightly so I could get it over a regular swivel flare adapter.

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