Beer backed up in gas line... what to do?

Lesson learned (I'm putting this up top for those who deem this TL;DR)
Before attaching a different pressure gas line to the keg, do this.
1) Remove gas supply from keg. In my case, 30psi
2) Pull PRV to vent the gas out of keg. I believe this is the crucial step which would have prevented the beer backup.
3) Attach new gas supply line to keg. In my case, 12psi

EDIT - Important detail I missed! The 4 channel manifold has integrated check valves. Hoping this means I'm safe! Product seen here:
http://www.ritebrew.com/product-p/843667.htm

Night before, I force carbed the keg at 30psi. Rocked the keg, rolled it, put it in the cold keezer with 30psi still on it. This morning, I wanted to replace the gas supply to the keg with a serving pressure (12psi) line. I forgot to vent the keg before attaching the 12psi line and as soon as I attached the QD, beer shot up into the gas line. The good news (maybe?) is that the beer didn't go far up the tubing. It settled about halfway up the line.



It might be a bit tricky to see in image above but, yes, beer is about halfway up that gas line. I closed that valve on the manifold and removed the QD from the keg. Here is a photo of the connection point of the gas line to the manifold channel. Note that beer is not near it.



At this point, I pulled PRV to fully vent keg and attached a different QD from same manifold to the keg. No backup, yahoo.

So, the paranoia sort of diffused. I decided to remove the line from that manifold channel. Got the wrench and started loosening the nut at the manifold side of the line. As soon as I did that, the beer started pushing up towards the manifold, darn. The smarter choice, I think, would have been to detach the QD from the line thus allowing the beer to flow out of the tubing. At least, that's what I assume.
Anyway, sorry that I don't have a photo of this. The manifold channel's valve was closed, not sure if that had any positive effect on my efforts to keep the beer out of the manifold. Got the tubing off and rinsed it. I made sure to get a clean, dry napkin and I rubbed it around the manifold connection point. Not damp. I then held the napkin under the channel and opened the valve to "blow out" whatever may have been in there. Napkin remains dry.

The large worry is for all the caution I've been taught about beer backing up into a manifold. I have never taken apart a manifold to clean it. I am nervous about trying that and, if I don't need to do it, I would like not to. Can the experts please weigh in with their recommendations on what I should do next? Thank you!

 

I did same thing lol. It blew back into my secondary regulator and all the way to my main regulator. I had to take them both apart to clean . After cleaning with hot water I left them broken down for a couple days to make sure they were dry . Put em back together and no issues . Wish my regulator had the anti back flow valve but now I'm just careful when I'm changing stuff up .

 

That just reminded me that the manifold and primary regulator have integrated check valves. May I stop worrying now?

 

Yeah if you have check valves your probably alright .

 

Count your blessings you used a transparent line for the gas line, if it was opaque and you couldn't see what happened, it might have ended up way worse like Jag75's contaminated regulators.

The check valves definitely saved you there, it was probably that which kept the beer halfway along the line in the first place, the liquid would advance along the line, compressing the gas between it and the check valve until the pressure balanced the pressure in the keg. When you started disconnecting the manifold side of the line, that pressure was released and the remaining pressure on the QD side pushed the liquid towards the low pressure side. You are right in the retroactive determination you should have released the QD first.

 

AMen.

AMEN. When setting this up, I skipped the usual red color gas lines. I am grateful that someone convinced me to do that. ;-)

So, it appeared that the beer got close to the channel connection of the manifold but I couldn't tell for sure. See above re: blowing CO2 out of that channel and getting a dry napkin. That said, I think it's safe to say I'm safe. Agree?

AMEN!

Super grateful I've got those check valves. Thanks to all for the insight! RDWHAHB, case closed.

 

Liked that your at a beer event , not the beer spraying everywhere and messing up someone's regulator lol

 

I had the same problem once except that the beer went all the way back to the valve on the gas distributor. I have every reason to believe those valves are one-way only and beer didn't go any further back than that.

Took everything apart and gave it a good soak/rinse/dry, and no problems I'm aware of.

Now the first thing I do any time I get a new keg is trim the gas side little dip tube up so it is basically flush with the inside top of the keg, above where I will ever have the liquid level. Doesn't matter what the pressure differential is. Problem solved.

 

This is definitely a tough lesson I have had to learn as a new kegger. I always have to think about my 3 keg setup as a system all at the same pressure, all interconnected. If I'm going to change anything with one keg, I have to shut off supply to the others. It's mostly automatic now, though have definitely f'ed up.

 

Put a check valve on every QD and at the input to the manifold. Problem solved.