Cornie Pressure loss

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Top Cat
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Cornie Pressure loss

Post by Top Cat » Wed Nov 29, 2017 10:51 am

Cornie newbie here.
Having just purchased a kit, I thought I should better pressure up and check that the keg would not leak, to avoid any problems when I put beer in it in about a weeks time.
I noticed the stainless outlet tube in the keg was bent going straight to the centre bottom of the keg. I subsequently took it out and straightened it, I also had to take 30mm off the end to give me a little (8mm) clearance from the keg bottom. I have put this down to someone else not fitting a new tube correctly!
I pressured the keg up to about 22psi to seal, relieved to about 18psi then turned the gas bottle off. I noticed after about 18 hours the pressure had dropped to 8psi. I don't know whether a drop in temperature of about 8 deg c overnight would have any influence.
Is this pressure drop normal guys? Or should I be talking to the supplier. Incidentally I did put some soap suds around the outlet disconnect after I reconnected, there didn't appear to be any bubbles!
Thank in anticipation.

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vacant
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Re: Cornie Pressure loss

Post by vacant » Wed Nov 29, 2017 11:12 am

The dip tubes I have are bent and reach to the middle of the keg with a gap of a few mm. I believe some people hack a cm or so off to prevent yeast getting sucked up. I'm happy with mine as it doesn't seem to draw any settled yeast up until the very last moment.

Turning off the gas isn't enough, you have to disconnect it from the keg to rule out leaks in the JG fittings and beer line.

I assume you've also tested with suds around the PRV, inlet post and lid?
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Kev888
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Re: Cornie Pressure loss

Post by Kev888 » Wed Nov 29, 2017 12:48 pm

Yes the dip tube was normal before you altered it; they all go to the bottom of the keg, which is at the middle of its base, since that leaves least product behind when dispensing. They are designed to dispense soda syrup, which doesn't (AFAIK) have sediment to worry about.

For beer with sediment, some people simply discard the first pint or two, others shorten the tube slightly as you have done and lose a pint or two at the end instead. Though straightening it is perhaps slightly less ideal since the sediment (like the base) will tend to be lower in the middle, so having the dip tube there means it need not be shortened quite as much.

The drop in temperature will indeed cause a reduction in pressure; though just off the top of my head that seems more than I'd have expected. Did you have any liquid in the keg? If so then (like beer) it would absorb some of the CO2.
Kev

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Re: Cornie Pressure loss

Post by PeeBee » Wed Nov 29, 2017 6:24 pm

You'll have figured from the replies that the dip tubes are bent. But not all are bent! Some are straight and flex so the end is in the middle (the keg might have a small well indented in the middle). Some are straight, but the keg has a radial indent in the base so the dip tube doesn't flex. You might even have a keg with such a radial indent but someone has retro-fitted a replacement dip-tube which is bent - that would cause a bit of head-scratching seeing it for the first time.

But you will have also figured from the replies that some people cut 20-30mm off the end of the dip-tube anyway so it can't suck up settled out yeast from the bottom.

I go a step further and cut the dip-tube so it is only 35mm or so long (or buy a "gas-in" dip-tube). Silicon tube is then pushed onto the shortened dip-tube, and a floating intake fitted to the other end. The intakes I use are a component from the "Caskwidge" system and cost about 7 quid - quite an expense having converted my dozen kegs to them. http://www.caskwidge.com/shop/index.php ... r=1&page=3.

As for pressure drops you've been given the answer above: Any water (of beer) in the keg will dissolve carbon dioxide and the pressure will drop (by a lot), or if you have any disconnects fitted to the keg for the test you'll be seeing any leaks in what is attached in addition to any leak in the keg (the disconnects can leak too). As you've bought a keg "kit" you probably should expect new lubricated seals in the keg and no sub-standard seal faces (dinted lids, etc.). I don't use soap-suds for testing, especially the lid seal, or you might end up with soap in the beer (if testing "live" kegs) - I use Stat-San which has a foaming agent in it.
Cask-conditioned style ale out of a keg/Cornie (the "treatise"): https://drive.google.com/file/d/0BwzEv5 ... rDKRMjcO1g
Water report demystified (the "Defuddler"; removes the nonsense!): https://drive.google.com/drive/folders/ ... sp=sharing

Top Cat
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Re: Cornie Pressure loss

Post by Top Cat » Wed Nov 29, 2017 7:59 pm

Thanks for the help guys.
Since some of your replies I've checked all inlet, outlet, pressure relief and main cover seal, all seem to be ok. I get your point PeeBee about suds in beer, I bought some star san a few days ago to use in the keg and I'll use that to check for leaks. I'm happy with the outlet tube, I may loose up to the last pint, but I can handle that. What procedure do you cornie users find best when finishing dispensing for the night and leaving for a few days. Do I
turn off the gas only, or pull the inlet disconnect off, or both disconnects?
Once again,thanks for your help in anticipation.

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Kev888
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Re: Cornie Pressure loss

Post by Kev888 » Wed Nov 29, 2017 9:02 pm

Top Cat wrote:
Wed Nov 29, 2017 7:59 pm
What procedure do you cornie users find best when finishing dispensing for the night and leaving for a few days. Do I
turn off the gas only, or pull the inlet disconnect off, or both disconnects?
Unless force carbonating, I tended to turn off the gas cylinder - just in case any leak loses all the gas. You could in theory pull off the gas disconnect, but sometimes (though rarely) these seat/seal imperfectly, as do the keg post/poppet seals, so it isn't quite as certain as using the cylinder valve. If you have several cornies that you may want to isolate separately, you can get inline valves, manifolds or gas management boards to do that.

You could apply the same logic to the beer/product side too, but for some reason I never bothered with shut-off valves there. I suppose the beer side is simpler, and undetected beer leaks are less likely than with the various regulators, lid seals and PRVs that can all quietly vent invisible gas.
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Re: Cornie Pressure loss

Post by Fil » Thu Nov 30, 2017 8:04 pm

Ha thats a contentious subject you stumbled on with the hacking off of your product out dip tube.. I run some kegs unmodified and the result is a dirty 1/2-1pint when first poured which removes most of any residual sediment, leaving a clean pour for the remainder of the keg. And i also use caskwidge floats which pour clear from the first tapping But leave a residual mass of liquid and sediment in the keg equating to a similar volume as an unmodified kegs first dirty pour.

As for the 'gas loss'? its probably due to the temp drop and absorption into the beer.. google kegging charts for tabular representations that can help you understand how pressure temperature relate to the volume of c02 that can be disolved in a beer https://www.google.co.uk/url?sa=t&rct=j ... 7178,d.ZG4
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Re: Cornie Pressure loss

Post by PeeBee » Thu Nov 30, 2017 8:13 pm

Top Cat wrote:
Wed Nov 29, 2017 7:59 pm
... What procedure do you cornie users find best when finishing dispensing for the night and leaving for a few days. Do I turn off the gas only, or pull the inlet disconnect off, or both disconnects? ...
I effectively do all three. But it is a solution for desperate worriers only. The main (primary) regulator has an inbuilt solenoid valve (many "aquarium" regulators have them) which is switched on (opened) by a delay switch like found in shared hallways - I switch the gas on and a few minutes later it switches itself off. Each gas line to a keg has a solenoid valve so having switched the gas on I have to then select the keg to dispense from. And each beer line has a solenoid valve too which is on the same circuit as the gas-line valve (so I only have to select the keg once). Having a valve on the beer-line isn't for leaks but because I use hand-pumps: It prevents a hand-pump from working when the gas supply is off because hand-pumps keep working with corny kegs even when no CO2 can replace the pumped beer because the pump will suck air past the keg lid and/or poppit valve in the disconnect resulting in off beer a few days later.

Okay , so I'm paranoid. :wacko:
Cask-conditioned style ale out of a keg/Cornie (the "treatise"): https://drive.google.com/file/d/0BwzEv5 ... rDKRMjcO1g
Water report demystified (the "Defuddler"; removes the nonsense!): https://drive.google.com/drive/folders/ ... sp=sharing

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