Pressure transfer question

[Airborneguy]

I completed my first closed pressure transfer today. I experienced an issue I have a question about. From the regulator about 6” down the gas line froze nearly solid and I lost way more CO2 than expected. Everything else went to plan. This regulator did not previously have a leak and it is used often. After it warmed back up, I raised the pressure back to 10+ (I pushed at 2) and it worked. I found no leaks.

Is it possible that the regulator leaked because of the low pressure I was pushing? Did I have it set lower than necessary?

 

[sibelman]

gas line froze nearly solid

?? A picture is not forming in my mind about this freezing and gas loss. Maybe explain more?

leaked because of the low pressure

This doesn't seem likely at all.

 

[Airborneguy]

?? A picture is not forming in my mind about this freezing and gas loss. Maybe explain more?

This doesn't seem likely at all.

Hopefully this helps. I’m often not great with descriptions.

 

[Airborneguy]

If you look close, everything from the adjustment knob down is frozen solid.

 

[day_trippr]

That could only happen if there was a local leak. I suspect one or the other location flagged - but it's also possible that PTC fitting is cracked...

Cheers!

 

[Airborneguy]

That could only happen if there was a local leak. I suspect one or the other location flagged - but it's also possible that PTC fitting is cracked...

View attachment 846865

Cheers!

I agree but weirdly it never leaked before and after it defrosted, I checked extensively and could find no leaks with it filling a keg at 30psi.

I just want to clarify that the adjustment knob above was also frozen solid and immovable.

 

[mashdar]

How fast did transfer go?

Expanding CO2 will drop temperature pretty significantly from 600psia to 17psia.

Strange stuff also happens if you get liquid CO2 in the regulator. Did you move the tank with the valve open?

 

[day_trippr]

There's another possibility though it's an outlier imo: you were using so much CO2 at the fermenter end that it froze everything on the low side of the regulator. An analogy: when I used to brew outdoors with propane, on a really humid day when I was still bringing the kettle to a boil (a BG-14 element at pretty much max power) the tank and neck and regulator would all get frosted over pretty thickly.

But unless your were moving a very large quantity of beer through a pretty wide bore hose I don't think you could get anywhere near that rate of flow. So I'd still finger a local leak...

Cheers!

 

[mashdar]

Also do you know about closed gravity transfers? Saves gas and you can walk away and let it finish unattended.

 

[Bobby_M]

Possibly indicative of a siphon equipped tank sending liquid CO2 through the regulator.

 

[sibelman]

The liquid theory has legs, cuz the leak theory seems dubious: I would imagine a very high flow rate if the cooling was that severe. Presumably a very loud hiss of escaping, decompressing gas.

Outside my experience for sure.

 

[Airborneguy]

How fast did transfer go?

Expanding CO2 will drop temperature pretty significantly from 600psia to 17psia.

Strange stuff also happens if you get liquid CO2 in the regulator. Did you move the tank with the valve open?

No movement of the tank. The transfer took about 10 minutes for 5 gallons.

 

[Airborneguy]

Possibly indicative of a siphon equipped tank sending liquid CO2 through the regulator.

Is there a way to tell? This was my second tank, not the one I swap with you (that one is on my kegerator).

 

[Airborneguy]

The liquid theory has legs, cuz the leak theory seems dubious: I would imagine a very high flow rate if the cooling was that severe. Presumably a very loud hiss of escaping, decompressing gas.

Outside my experience for sure.

I was listening to a podcast with headphones so this is very possible.

 

[day_trippr]

Siphon tanks are usually marked as such. Otherwise I'd think with the regulator removed, opening the valve should produce something more than just "gas", but tbh I've never tried that with my siphon tank...

 

[Broken Crow]

Apologies in advance; I'm going to think out loud and though I've no answer, maybe it'll be some fuel for thought.
I don't capture fermentation gas to purge. I fill my kegs completely with Star San and purge with CO2 from my tank, usually doing 2-3 kegs concurrently. Purging goes a lot faster than transferring, in part because I use larger lines for it so, just a few minutes or so to purge a 5G keg and my regulator does get sweaty and cold, but rarely any frost..the only occasion I've had frost it was on the back of the regulator body and not on the fittings below. I am wondering about the coupler you have beneath your valve; Did it come that way or did you install it yourself?...This would be an 'out there' more esoteric possibility, but if the male coupler has a significantly undersized diameter (orifice), the rapid expansion into the female coupler is where the 'refrigeration' would occur (that's how our fridges, freezers and AC's work) and from the pics, that coupler does appear to be the coldest part, however unlikely that possibility.

 

[Broken Crow]

Something else occurred to me; In your picture, I notice the gas line is shut off so I'm assuming here that you took the picture after your transfer... In the pic; The gas line is pretty much much just hanging down in a natural position and I notice you don't use retaining clips on the collar. As much as I love duotights, I'm ham-fisted and don't always correctly process what my eyes are seeing and I've made some bad connections. I know that if you don't make a perfect right-angled cut, free of any nibs, you risk a leak.... even competent folk have made bad cuts on occasion, but with my medical issues those mistakes happen a lot more. What I did discover after a couple mistakes and one verifiably faulty part, was that even a seemingly good connection will leak if the line is bent too far to one side, and I've even had it happen when using clips.
Suggestion: Try turning on the gas in silence and without plugging in the diconnect to anything and bend and hold the line and disconnect into the same position as when you were transferring and listen for leaks,...maybe even bend a tighter radius. In my first kegerator when I installed my first EVABarrier/duotights, I got a gas leak if I didn't orient the keg so as to keep from bending the line in a too-tight curve.

 

[Airborneguy]

Correct the pic was taken after I noticed what was happening and shut the valve.

I'm going to attempt a second pressure transfer either later today or tomorrow afternoon. I'll report back.

 

[doug293cz]

The temp drop (due to evaporating and expanding CO2) will cause the components to shrink a little due to thermal "expansion." Different materials, esp. plastics compared to metals, expand and contract at different rates, thus something that was a tight fit at room temp, might loosen up at reduced temperatures. This is consistent with the leakage only happening when the plumbing is cold. Not a certainty, but something to consider.

Brew on

 

[jerrylotto]

Why not do a gravity assisted transfer under pressure? As long as you can get your source vessel higher than your destination vessel, you should be able to start a siphon as long as there's a continuous loop so that displaced gas in the destination vessel can return to the source.

 

[Airborneguy]

I may do it this way next time. Seems like it will use much less gas.

 

[mashdar]

I may do it this way next time. Seems like it will use much less gas.

The only tricks are managing pressure to start syphon and avoid blowing up the yeast cake. I had one where I hooked a 2psig keg to a 15psig fermenter, and got nucleation in the yeast cake, tearing it up and requiring a few more days for clarifying.

Ideally the keg would start just below the pressure of the fermentor to start liquid-liquid syphon, then hook up return gas-gas connection.

The one I have right now, keg is 15psi and fermenter is 11psi, so I'm going to:

• Set keg below fermenter
• Connect gas-gas line to keg
• Purge line
• Connect gas-gas line to fermenter (equalize)
• Connect liquid-liquid line to fermenter
• Purge liquid-liquid line
• Connect liquid-liquid line to keg
• Walk away
• Return later, note beer in gas-gas line, indicating keg is full to gas dip tube
• Drain some beer before/while hooking up to gas, or you risk back flow into gas lines.

edit: deleted these steps, because purging the liquid line also starts the syphon. Just went through the process.

• Disconnect gas-gas from fermenter
• Pull keg PRV to start flow
• Connect gas-gas line to fermenter

 

[jerrylotto]

The only tricks are managing pressure to start syphon and avoid blowing up the yeast cake. I had one where I hooked a 2psig keg to a 15psig fermenter, and got nucleation in the yeast cake, tearing it up and requiring a few more days for clarifying.

Ideally the keg would start just below the pressure of the fermentor to start liquid-liquid syphon, then hook up return gas-gas connection.

The one I have right now, keg is 15psi and fermenter is 11psi, so I'm going to:

• Set keg below fermenter
• Connect gas-gas line to keg
• Purge line
• Connect gas-gas line to fermenter (equalize)
• Connect liquid-liquid line to fermenter
• Purge liquid-liquid line
• Connect liquid-liquid line to keg
• Walk away
• Return later, note beer in gas-gas line, indicating keg is full to gas dip tube
• Drain some beer before/while hooking up to gas, or you risk back flow into gas lines.

edit: deleted these steps, because purging the liquid line also starts the syphon. Just went through the process.

• Disconnect gas-gas from fermenter
• Pull keg PRV to start flow
• Connect gas-gas line to fermenter

Good description of the process. One thing I would add is "tare your empty kegs" so you have a way to determine how empty or full they are.

 

[tracer bullet]

I'm a bit late, and it's been covered I think... I will agree that it's probably a PV=nRT thing. CO2 from the tank is depressurizing and cooling where it comes out, and it can cause things to get cold. With the right ambient conditions it could have ice form I suppose. As mentioned my propane tanks sometimes get really cold on the outside if I'm running the pot at full boil.

My transfers are like this: https://www.morebeer.com/articles/Closed_Transfer_Kegging

I purge a water filled keg with CO2, and leave just enough pressure in it (1/2 psi I'd guess) to also purge my transfer lines. Then I hook things up, and lastly open the spigot on the keg. Works really well. One of a variety of ways to do it of course.

I keep intending to use fermentation CO2 to purge my keg but haven't quite gotten to that.

 

[Broken Crow]

For what it's worth, I've taken to using a 12V diaphram racking pump and gas return line in a closed under pressure loop in order to save CO2.

 

[sibelman]

I keep intending to use fermentation CO2 to purge my keg but haven't quite gotten to that.

This is physically simple to do. I've gotten into the habit of sanitizing a keg at the end of a brewing day so it's ready to receive gas when fermentation gets going.

 

[rodduley]

@Broken Crow, do you have any pics of your pump in use? Sounds interesting.

 

[Broken Crow]

@Broken Crow, do you have any pics of your pump in use? Sounds interesting.

Part of the reason I went with a pump is that I'm disabled so arranging a gravity transfer is kinda extremely painful. I don't have pics of transfer from a fermenter, but I do have this transfer of my GF's cider from a sanke to the cornies I need to fit in my kegerator:

I don't make my own cider (yet) but my LHBS does a good one.
Here's the aliexpress pump that I've installed ball-locks on:

 

[Airborneguy]

Round #2

 

[Airborneguy]

This is the way going forward. I made one slight mistake by opening the spigot before connecting the gas to the fermenter. Pushed CO2 into the fermenter from the bottom, so there goes my cold crash. I won’t make that mistake again!

But anyway… this is great. Thanks for all the help. You’ve never been brewing too long to learn new tricks!