what happened when i ran out of CO2?

So I thought that I had my kegging set-up dialed in just right. I had my first keg online and pouring great. 40 degrees, 10psi, 5 feet of 3/8” line.

A week ago I put my second keg (two keg system) online, and force carbonated using the set it and forget it method. I poured both beers for about a week once the second was carbonated.

Then all of a sudden I noticed that my first beer got really foamy. I checked the regulator and found out that I was out of CO2. The source of the problem was a leaky blow-off valve on my second keg. I got air the very next day and swapped the lid on my leaky corney.

To repressurize the second keg, I bumped to the keg to 30 psi (also to check for leaks) and then disconnected the air. I turned the regulator back down to ten psi, and purged the lines to make sure my pressure reading was accurate. Then I hooked the first keg back up (the second is still disconnected). That was Wednesday.

Thursday I go to have a delicious beer from my first keg (the one that was always fine), and boom… I get a foamy mess in my cup. The keg never saw more than 10 psi. The beer was in primary for 3 weeks and secondary for 2 weeks and has been in the keg for 3 weeks with no problems.

What the hell happened?

Switch the lines on the kegs. If the problem stays with the keg, then you might have an infection in that one. If the problem stays with the line, give it a good cleaning.

There was no weird taste and the beer didn't taste drier..... Could it really be an infection this late in the game

How full is the keg? Mine tend to foam up for the last few glasses for some reason.

It's about 1/2 full. It is probably my best beer ever. Oak aged ipa....

These regulators will increase the outlet pressure as the inlet pressure decreases. You should notice your beer line pressure increase as the CO2 bottle gets close to empty...it won't do this for most of the bottle but when it gets towards the end it will. If it somehow were to stay this way for some time then that could do it but I've never had it happen to the degree you're talking about.

No temperature swings? Temp swings could def do this. For example, carbing just a few degrees cooler and then serving slightly warmer could cause it.

Just throwing stuff out there.

The problem may be the size of your line. 3/8" lines (unless you meant 3/16) are too big and are giving your no resistance what so ever. If the kegs have been to higher pressures and are higher than what you've had them at before.

Or, are you running two regulators? If you're not and you didnt disconnect the first one when you raised the pressure, it is up too.

These may seem like silly questions/responses...I just wanna help.

Nope only running one regulator, and yes, I have 3/16 lines. Real weird. Everything should have been on the up and up. Kegs stayed cold. I have a Johnson temp contoller with the bulb packed in freezer pack jell. I just don't know