CO2 Tank Pressure Drop

[slurms]

This is my first time kegging, so it's probably just lack of understanding or just being a bit paranoid.

I kegged about 3 gallons of beer and it's been sitting in the kegerator at around 13 psi for about 2 weeks. The 20lb CO2 tank sits outside the fridge, in about 65-68F ambient temperature. The high pressure gage was originally reading at 800 psi, but I just noticed today that it's now reading a little under 500 psi. I haven't checked the pressure too many times recently, but if I recall it read close to 800 psi a few days ago. CO2 usage consisted of a few oxygen purges, a few times that I disconnected the gages and everything (from not knowing what I was doing), and pouring a few pints. Checked for leaks at all connections by spraying starsan, nothing.

I know this gage is generally classified as "useless", but is this normal? It's probably fine, but I just don't want to find the gage in the red zone and be outta gas. I've read that a 20lb tank should last for dozens of kegs. I can put the tank on a scale (which is a pain since it's not a continuous reading) but being that there doesn't look like any leak, not sure how that would help.

 

[VikeMan]

The high pressure gauge will read the same (for any given temperature) until it is almost empty, at which point it will fall fairly precipitously. It's more of a binary indicator, and not proportional to the amount of CO2. But if it read 800 PSI before and 500 PSI now, with no temp change, you are running on fumes now.

Also, you generally can't tell if there's a leak by "looking," unless you are covering the connection points with soap or starsan solution and looking for bubbling.

 

[slurms]

Kinda what I figured but not what I wanted to hear.

Yeah I sprayed starsan all around and looked for bubbles. Didn't see anything but could have missed it. Just a pain if it is running out since the gas store has terrible hours...

 

[IslandLizard]

Weigh your tank with regulator and other stuff on it. If it loses weight beyond the oz or 2 you'd expect, you may have a leak somewhere, and start hunting for it.

Some scales do provide continuous reading, plugged into an outlet via an AC adapter.
@bracconiere

 

[day_trippr]

fwiw...

Cheers!

 

[slurms]

Weigh your tank with regulator and other stuff on it. If it loses weight beyond the oz or 2 you'd expect, you may have a leak somewhere, and start hunting for it.

Thanks for the tip. I've got it on a bathroom scale. Doesn't stay on, but I was checking it every few hours. Definitely leaking. Didn't see anything at the PRV, lid o-ring, or base of the posts. So my guess is it's at the post o-ring with the QD attached.

I did dunk the gas QD in water and noticed some bubbles coming from between the nut on the tube and the threads on the QD, but could have just been residual air. Either way, I put some keg lube on the QD "washer" and that seemed to make it go away.

My bet is that there's a leak in the gas post o-ring. Put a new one on at first but maybe it was defective. I just swapped it out with another new one, lubed it up, and attached everything back up. Just going to check the CO2 tank weight at the end of the day (moot point since it's borderline red zoning it).

fwiw...

Thanks, I came across this in some searches. Pretty interesting, and also a jerk move the tank only tells you it's woes when it's too late...

 

[IslandLizard]

Make sure to use those plastic "fish eye" flare washers between metal to metal MFL surfaces, such as a flare nut connection to regulator or manifold.

There are many threads and posts on troubleshooting keg systems. Worth looking around.

Make sure the o-ring on the keg post is the correct size, and fix all possible leaks, or you will keep blowing through tanks.

My 20# swap tank lasts around a year or a bit longer, depending on use and beer events we serve at as a club. One of my first years I lost half a 15# in half a day on a loose MFL connection I had forgotten to tighten while at an event. So I now double check my work.

@bracconiere uses a permanently-on scale to monitor CO2 usage. He even burst carbonates by CO2 weight. I guess you'd need a scale that reads in 0.1 oz, and is consistent enough. I'm thinking of going the same route for my keezer too, just in case.

 

[slurms]

Okay, so I looked a little more into this. I have a dual regulator, only using one currently. Shut off both regulator valves, opened the tank, Set the regulator I've been using to around 15 psi, and then shut off the tank.

Wouldn't ya know it, the tank gage was slowly going down, so maybe there is a leak in the regulator I'm using.

The odd thing is that I unscrew the regulator (to reduce the pressure to zero), release its gas, and then the regulator pressure starts to increase, up to 5 or 6 psi. Even though the tank is turned off and the regulator is completely unscrewed. FWIW, the other regulator doesn't do this.

There's definitely a problem with this regulator. Assuming the leak is actually there, and not the connection to the tank itself, my guess is that this will continue even if I use the other regulator, no? Has anyone else come across this problem? I don't want to get another tank of gas, use the other regulator, and still have the problem child doing its thing.

 

[slurms]

Make sure to use those plastic "fish eye" flare washers between metal to metal MFL surfaces, such as a flare nut connection to regulator or manifold

The only flare nut connection is the connection from the tube to the gas disconnect, everything else is a barbed connection (and the main threaded connection to the tank). I did find a small leak in the flare nut, but that might have just been trapped air when I submerged it into water.

Make sure the o-ring on the keg post is the correct size, and fix all possible leaks, or you will keep blowing through tanks

The o-ring that was on there was a new replacement from online homebrew store. I hope they gave me the right ones... The one I replaced it with was bought at Lowes but should be the same size (but has only been on there for a few hours).

If I can get one of those scales for a good price, I'll probably do that too. Spent enough on this hobby so far, what's a few more bucks, right?

 

[IslandLizard]

Here's the scale @bracconiere uses:
https://www.amazon.com/gp/product/B00KYA0RC2/
Here's a post in one of the threads showing it:
https://www.homebrewtalk.com/threads/keg-force-carbing-methods-illustrated.73328/post-8960886

 

[ScrewyBrewer]

Mix dish soap and water solution, crank the pressure up to 30 psi then check closely for bubbles.

 

[IslandLizard]

The o-ring that was on there was a new replacement from online homebrew store.

Chances are it was the correct size, then.

Double check:
The o-ring should just fill the groove, without much stretching, leaving very little space above and below. It should show an ever so slight projection outside the groove where the QD will compress it to create a positive seal.

Use keg lube on all your o-rings, refresh when needed.

 

[bracconiere]

I lost half a 15# in half a day on a loose MFL connection I had forgotten to tighten while at an event. So I now double check my work.

uses a permanently-on scale to monitor CO2 usage

damn man! i forgot i have some flare gas connects , and i swear i lost 0.5oz's overnight last night!. gotten tighten them, thanks for the tip!

 

[bracconiere]

and sure enough one of my flares was lose! thanks again!


(and i still love my scale, and HBT!)

 

[bracconiere]

oh and i swapped my tank in july, they shorted me, and with a tare weight of 33.4, i got 13 pounds of co2 in my 20#'er. now my scale reads 39lb's 14oz's or so. after carbing and pushing about 37 5 gallon kegs, my high pressure gauge is reading 700 psi. so i think i'm out of liquid. but thanks to @IslandLizard i'm hoping my minor leak is cleared up! i'll have to try and remember to not forget what the scale reads when i go to bed, and calculate the earths rotation and sun's gravity! (that's serious! i love this scale! if an o-ring even passes minor gas, you know i'll smell it!)

edit: i'm not sure this is off topic, but i think 1.5oz's co2 is too much to burst carb with, think maybe 1.3 would be better! lol. and now off to update force carbing thread!

 

[slurms]

I'm fairly certain the leak is coming from somewhere in the regulator or the regulator connections (not to say there isn't a leak in the gas disconnect to the keg...). While the starsan/soap trick didn't show any bubbles, the high pressure gage dropped to zero after a minute with the regulators' valves turned off and the tank shut off as well. Also, one of the regulators will only go down to about 6 psi with the set screw completely unscrewed and never reach zero psi unless disconnected completely from the tank (likely a separate issue, but could be connected). AIH said they would be glad to check this out for me. I'll be out of my regulator but hopefully they can find out what the heck is wrong with it.

 

[day_trippr]

Yeah, that's definitely not right. It should take at least days if not weeks (if not even longer) to bleed down a tight regulator. I have a regulator on a cylinder I use for closed transfers that I haven't used since the end of June that is still showing a good 400psi on the high pressure gauge. Ironically that same Chudnow regulator had a tiny leak around its PRV stem threads which I had to fix, so I had been keeping an eye on it (still am I guess )...

Cheers!

 

[IslandLizard]

Also, don't leave the tank valve in a halfway open position. It should be left all the way open or all the way closed, never in between.

Surely, yes, a weird acting regulator needs to get interrogated thoroughly.

You can submerge the regulator in a tub with water, to check for leaks (bubbles), keeping the dials dry and above the surface. Just don't turn the knobs while under water or wet.

 

[SanPancho]

did you try unscrewing the 2nd regulator and isolating the one acting funny? all you typically need is a 1/4 plug. also if you have the check valve style shutoffs sometimes those can go bad and you'll get backflow into the regulator....

also- if you do go back to brew shop, get yourself some thread sealant. its a paste you coat onto the threads to get full seal. teflon tape is not for making seals, its for keeping threads from binding. the paste will harden into a seal. if brew shop doesnt have it you can use plumbers thread seal as long as it says its ok for potable water usage.

 

[VikeMan]

teflon tape is not for making seals, its for keeping threads from binding.

When used with tapered threads, its for both.

 

[IslandLizard]

get yourself some thread sealant. its a paste you coat onto the threads to get full seal.

Such as Blue Monster?
https://www.homedepot.com/p/Blue-Monster-4-oz-Pipe-Thread-Sealant-76009/306136418
But use it together with teflon tape!

teflon tape is not for making seals, its for keeping threads from binding. the paste will harden into a seal.

I don't agree with that, teflon tape is used in many applications, including natural gas and propane gas connections, [edit] even ones that are not tapered. Use yellow tape for gas, it's about 2x as thick as white tape. But you could double up the number of turns on white tape when in a pinch.
I'm now using gray tape which is 4x as thick as white tape.

The paste actually should not harden, it becomes thicker, tougher, but never hardens, that's the point of a good seal.

 

[SanPancho]

When used with tapered threads, its for both.

No, its really not. it just doesnt do the same thing that paste does. every reefer tech, plumber, steamfitter, glycol installer and sprinkler fitter on our jobsites uses paste type sealant. a few dont even use tape at all.

 

[VikeMan]

No, its really not. it just doesnt do the same thing that paste does. every reefer tech, plumber, steamfitter, glycol installer and sprinkler fitter on our jobsites uses paste type sealant. a few dont even use tape at all.

It may be that paste is more effective. That doesn't mean that "teflon tape is not for making seals."

 

[SanPancho]

Such as Blue Monster?
https://www.homedepot.com/p/Blue-Monster-4-oz-Pipe-Thread-Sealant-76009/306136418
But use it together with teflon tape!


I don't agree with that, teflon tape is used in many applications, including natural gas and propane gas connections, [edit] even ones that are not tapered. Use yellow tape for gas, it's about 2x as thick as white tape. But you could double up the number of turns on white tape when in a pinch.
I'm now using gray tape which is 4x as thick as white tape.

The paste actually should not harden, it becomes thicker, tougher, but never hardens, that's the point of a good seal.

i dont mean harden and become brittle, i mean it in the sense that it seems to firm up more (dry out a bit?) and start to be more like the glazing on windows vs the runnier stuff like when it comes out of the tube or the bottle.

the super thick tapes are nice, like blue demon, monster, etc. but even with those guys all our pros still use paste on top.

think of a time when you unscrewed someone else's tape job, or your own, where they just went apeshit and did like a dozen wraps. there's a ring of bunched up tape sitting way up high on the male end, and often nothing further down. thats no bueno. i've been lucky enough to get some "free" union tradesman schooling on jobsites from the bay area all the way down to san diego in my lifetime, (as well as a neighbor and brother in law who work for major utilities), and they've always got a brush bottle of paste with them.

agree or disagree, no sweat off my back. but you wont get the same seal with only tape.

 

[IslandLizard]

[...] even with those guys all our pros still use paste on top.

Paste as in the red pipe paste that was used with hemp?
If not, what kind of paste?

 

[bracconiere]

every reefer tech

that was used with hemp?

lol, i just had to google "reefer tech" (it sounded kinda like a trimmer back in mendo!)

 

[LittleRiver]

I had a leaky connection between the regulator and the tank, and apparently this is fairly common. It didn't show up until I turned the whole shebang on its side so the starsan I was spraying would pool up in the nut, revealing tiny bubbles.

 

[SanPancho]

Paste as in the red pipe paste that was used with hemp?
If not, what kind of paste?

ha! you mean dragon's breath? i'm not so proud as to deny i got sold a stick of that stuff once at berkeley. even smoked it. d'oh. no bueno.

the most popular one seems to change depending area, who the wholesale supplier is, etc. but most of the plumbing suppliers make it, blue devil, rector seal, otey, etc. the one i see alot in bay area is in a sort of yellowish tan brush bottle. cant remember the name for the life of me.

tanks, taps, fittings, and other stuff we have one i cant remember the name of even though i can see the damn red/white tube in my mind's eye.... we used to have something called "plus co" but i think it was expensive, and then we also will use loctite 542 as long as we can let it set for at least 24 hours. the loctite isnt technically FDA rated, but its inert after setting. (like jb weld). the problem is that when we're in the cold room or a cooler box, its kinda hard to be sure 24 hours is enough for it to set given the low temps. its a better safe than sorry situation so in the cold temps we use the red/white tube which i cant friggin remember the name of.....


EDIT- i remember finally. its rector seal, but its the "soft set"version, which i dont think ive ever seen at an HD/lowes. or at least, ive never seen the yellowish bottle there.

 

[SanPancho]

Also, don't leave the tank valve in a halfway open position. It should be left all the way open or all the way closed, never in between.

i thought that was just for nitrogen? since it has a different connector style. co2 is just threaded down onto the disk or rubber oring.....

 

[day_trippr]

The cylinder valve has bottom and top seals that are highly effective at the limits of travel, and also has a stem packing. The popular opinion is to not rely on the stem packing...

Cheers!

 

[SanPancho]

wait- you're referring to the on/off knob of the actual tank valve being the source of the leak? i was talking about the connection of the regulator assy to the tank outlet, where we used to put those little paper disks, and now there's an embedded oring.....

 

[day_trippr]

Yes, the cylinder valve "knob". Not the coupler end...

Cheers!

 

[IslandLizard]

ha! you mean dragon's breath? i'm not so proud as to deny i got sold a stick of that stuff once at berkeley. even smoked it. d'oh. no bueno.

Interesting to know!
Now I was talking plumbing... old-fashioned (reddish brown) pipe dope and hemp fiber to make a seal on threads. Life before PTFE.

 

[SanPancho]

maybe..... i feel like our super old galvanized pipes often have a kinda/sorta reddish substance on the joints. but cant say it looks like it has anything fibrous in it. maybe it was crushed when it was tightened down? its a possibility but couldnt say for sure.

we do still see pipe joints that were sealed with lead though...... yikes

 

[beeramI]

This is my first time kegging, so it's probably just lack of understanding or just being a bit paranoid.

I kegged about 3 gallons of beer and it's been sitting in the kegerator at around 13 psi for about 2 weeks. The 20lb CO2 tank sits outside the fridge, in about 65-68F ambient temperature. The high pressure gage was originally reading at 800 psi, but I just noticed today that it's now reading a little under 500 psi. I haven't checked the pressure too many times recently, but if I recall it read close to 800 psi a few days ago. CO2 usage consisted of a few oxygen purges, a few times that I disconnected the gages and everything (from not knowing what I was doing), and pouring a few pints. Checked for leaks at all connections by spraying starsan, nothing.

I know this gage is generally classified as "useless", but is this normal? It's probably fine, but I just don't want to find the gage in the red zone and be outta gas. I've read that a 20lb tank should last for dozens of kegs. I can put the tank on a scale (which is a pain since it's not a continuous reading) but being that there doesn't look like any leak, not sure how that would help.

I know this probably isn't it but.....I chased a CO2 leak in my keezer for weeks. It turned out being the air release valve on a corny keg. When I took it apart it looked like beer had built up and dried on the air release stem and couldn't create a tight seal. I always throw my keg covers in StarSan when cleaning my keg but never thought to take apart the air valve.

 

[shoengine]

I have a leak in my kegerator setup somewhere, and it is just daunting trying to track it down with two manifolds and three kegs. There are so many interfaces!

 

[beeramI]

Did you try soapy water to look for bubbles? Or, if you have homebrew kegs, try looking at the air release valve. I took mine apart and there was a miniscule build up of dried beer on the stem that wouldn't allow an airtight seal.

 

[slurms]

This thread took a turn for a bit (I think there's a pun in there...). Anyway, some good stuff in here.

I sprayed Starsan and put soapy water on all the connections that I could think of. Nothing showed signs of bubbles. Only places that I think it could be is the gas disconnect (which bubbles won't really work there) or somewhere in the regulator itself.

Unfortunately, the homebrew site I got the regulator from wants me to send it to them to check it out in their work shop, and send it back to me when they're done (huh, sounds like the Grinch). So I'm out of a regulator for a while. But I did score 2 more 20# tanks for $80. Probably excessive to have 3 big tanks on hand, but will at least keep two filled. Maybe unload the third one..

 

[bracconiere]

Nothing showed signs of bubbles.

for $27 you can get a scale for your tank. accurate to the 1/10th ounce! if you suspect a QD i'd pull it and see how the scale changes over a day.

i usually just flail wildly until the scale stays solid! it makes burst carbing great too! lol (co2 leaks suck, but as G.I. Joe says knowing is half the battle!!)