[DrewG]

I have a 2 tap dorm fridge style kegerator.

My normal procedure to carbonate is to cold crash in the fermentor to 33 F, transfer to a keg, purge 02 and put c02 on it at 10-12 psi depending on what I'm shooting for. Typically in 5-7 days I'm where I want to be.

8 days ago I racked a brown porter to a keg. I had not cold crashed this beer. Put the keg in the kegerator without hooking it up to the gas to allow it to chill for 24 hrs. Hooked up the gas the following evening and let it sit for 4 days. Checked it. Nothing. Figured it must have been a temp issue and turned the gas up to 15. 2 days, no difference. took it to 20 psi, rocked the keg for 5 minutes. 2 days, no difference. Put another keg in at the same 20 psi (exact same procedure, racked warm, no gas for 24 hrs to chill) and that one is fully carbed in 3 days, porter still the same. Leak tested the keg with soapy water, no visable leaks. Pull the PRV, there's plenty of pressure in the keg.

Ideas?

[DrewG]

Here's something else I've been pondering: Does the solubility of C02 into solution change as the temp of the solution drops? As in, if i keg at 66 F, apply gas pressure at 12 psi and cool the keg at the same time. At 66 F with 12 psi I should theoretically achieve 1.6 volumes. So if the keg chills to 40 F over time do I then get 2.6 volumes with the same 12 psi or is the solubility of gas into solution somehow locked in at the original temp (65) that gas was applied at?

[hopfenundmalz]

Yes the pressure you need changes with temperature.

There is a table in the Daught Beer Quality Manual, page 68. Search and do a download.

[DrewG]

I have it printed at home somewhere. So, if solubility changes along with temp, this keg should be overcarbonated by quite a lot by now.

[HydraulicSammich]

Also, along with temp, head space is a big factor.  Overfilling the keg, higher initial temps, and prolonged higher temps, say in the keaser as opposed to a lagering chamber, increases the time dramatically to carb the keg.

[DrewG]

head space is a big factor

Maybe an inch of freeboard in the keg, which is pretty full, admittedly. However the keg next to it was filled to the same level and its carbed up fine.

[beersk]

Hmmm, grasping at air, but have you made sure the valve on the manifold is on? I've not left mine on before and realized it a day or so later.

[DrewG]

Hmmm, grasping at air, but have you made sure the valve on the manifold is on?

It's on. Dumped the PRV a few times to be sure it's getting gas. Plus the line from that manifold leads into a splitter which feeds both kegs. 

[HoosierBrew]

Think it's possibly filled a little higher than the other?   2 or 3 batches ago I filled a keg a little higher than I normally do, and it took forever to carbonate.  There needs to be a certain amount of headspace to carbonate accurately using the chart.  I sanitized a big metal ladle, dipped out some from the top of the keg, repurged andrepressurized, and it carbonated like normal.

[morticaixavier]

Think it's possibly filled a little higher than the other?   2 or 3 batches ago I filled a keg a little higher than I normally do, and it took forever to carbonate.  There needs to be a certain amount of headspace to carbonate accurately using the chart.  I sanitized a big metal ladle, dipped out some from the top of the keg, repurged andrepressurized, and it carbonated like normal.

seems like it would have been easier to pour a pint from the tap no? 

[DrewG]

Pint glass would be easier to drink out of than a ladle for sure 

I've pulled a number of samples, so I think it would be low enough by now that headspace wouldn't be an issue.

I'm frustrated enough at this point I'll probably go home and crank it up to 50 pounds and shake the damn thing like it owes me money

[HoosierBrew]

Pint glass would be easier to drink out of than a ladle for sure 

I've pulled a number of samples, so I think it would be low enough by now that headspace wouldn't be an issue.

I'm frustrated enough at this point I'll probably go home and crank it up to 50 pounds and shake the damn thing like it owes me money

   Would have been easier , except that I wanted to see whether the gas in tube was covered by beer, for my own curiosity. 

[gsandel]

small/slow gas leak on keg's seal or gas in post?  That would explain having pressure in keg (in testes), but not carbonating.  I have had an agrivating slow leak on a keg posts before, where I can't find it but the keg is always losing pressure over a day or so.

[DrewG]

small/slow gas leak on keg's seal or gas in post?  That would explain having pressure in keg (in testes), but not carbonating.  I have had an agrivating slow leak on a keg posts before, where I can't find it but the keg is always losing pressure over a day or so.

Checked lid seal and posts with soapy water the other day. No leaks, at least there

[gsandel]

Checked lid seal and posts with soapy water the other day

I had the same no apparent leak....however, I think that my leak was when the gas was attached to the post.....it let gas in to a certain extent and then it slowly escaped.  I was able to carbonate it, so I think my issue was when I unhooked and rehooked it up at some later time.