Co2 in tank dropped overnight

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nolimits67

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I currently have 2 Corny's waiting to be served in a few of weeks. I have them stored like I store my fermenters when fermenting. I fill an icechest with water right up to where I have a liquid crystal temperature gauge stuck to the side. Throw a bottle of ice in their twice a day and keep the whole thing covered with a couple of towels. This way I can keep my beer at around 65 degrees despite the room sitting at 72+.

Anyway, this is my first time kegging and I decided to force carb as soon as I got the beer in my kegs. I put them in the cooler, got the reading on my temperature gauge down to 65 degrees, attached the Co2 tank and cranked it up to 28PSI on both kegs.

I've had the kegs sitting this way for 2 weeks now. I know they are probably carbonated to my liking at this point, however last night I looked at the Co2 tank gauge and it seems to have dropped from a little under 850PSI to a little under 800PSI.

I've watched this gauge over the last 2 weeks and haven't seen a drop like this. Did a leak spring up or something? I closed my Co2 tank on my way out the door this morning but left the fittings attached to the cornys.

Any idea why the drop? Suggestions, comments about my first kegging? Peace of mind? Getting married in 3 weeks and serving this 10 gallons at the reception.. last thing I need at this point is to worry about my brew.
 
was there a temp change to your co2 tank? The high pressure gauge is totally useless to tell you how much co2 you have left. It reads pressure in the tank, until it is almost empty then the gauge drops like a rock.
 
CO2 is a funny thing to watch on gauges. It's a liquid under pressure - with that liquid boiling off to fill the headspace in the tank. It'll read at right about 750 psi as long as there is liquid remaining in the bottom of the tank. Once all the liquid has boiled off into gas and you only have a tank full of gas the gauge will finally start dropping. That's a sign that you will need to refill the tank. Was this a new fill of CO2? Have you been using it for a while? If it's a fresh tank you may have a leak. If it's a tank that's been used for a while it's prob time for a refill / exchange.

Are you aiming for about 2.5 vols of CO2?
 
bucfanmike:
Temp change is a possibility. Come to think of it.. it hasn't rained in a couple of weeks and it stormed really good last night. It was quite humid and warm in the house this morning.

brycelarson:
This was a used tank that I got filled from empty. This is my first time using the tank, dual regulator, and Cornys. I put the kegs under pressure and practiced with water before kegging the beer. Didn't find any leaks anywhere. I am shooting for 2.7 vols of CO2.

While I'm on the topic... I've been trying to find a definitive answer (if there is one) on the topic of letting the beer age in the keg at room temperature purged of oxygen but not under continuous CO2 pressure.. or hitting it with constant pressure, chilled down before getting served, purging out CO2 and setting it at serving pressure.. I wanted to do a set and forget, but since I don't have a way to keep my kegs cold for the next few weeks I've just kept them under higher pressure (calculated by beersmith) to get it carbed up.

A few days before the wedding I'm planning to put the kegs in a fridge and get the kegs to 10PSI for serving. Can I just throw the kegs in the fridge still at 28PSI. When the kegs cool the pressure will drop right? Will this affect the carbonation? After this is done can I just reconnect my tank and set it at 10PSI?
 
nolimits67 said:
I currently have 2 Corny's waiting to be served in a few of weeks. I have them stored like I store my fermenters when fermenting. I fill an icechest with water right up to where I have a liquid crystal temperature gauge stuck to the side. Throw a bottle of ice in their twice a day and keep the whole thing covered with a couple of towels. This way I can keep my beer at around 65 degrees despite the room sitting at 72+.

Anyway, this is my first time kegging and I decided to force carb as soon as I got the beer in my kegs. I put them in the cooler, got the reading on my temperature gauge down to 65 degrees, attached the Co2 tank and cranked it up to 28PSI on both kegs.

I've had the kegs sitting this way for 2 weeks now. I know they are probably carbonated to my liking at this point, however last night I looked at the Co2 tank gauge and it seems to have dropped from a little under 850PSI to a little under 800PSI.

I've watched this gauge over the last 2 weeks and haven't seen a drop like this. Did a leak spring up or something? I closed my Co2 tank on my way out the door this morning but left the fittings attached to the cornys.

Any idea why the drop? Suggestions, comments about my first kegging? Peace of mind? Getting married in 3 weeks and serving this 10 gallons at the reception.. last thing I need at this point is to worry about my brew.
Click to expand...

The high pressure gauge doesn't work properly on CO2 tanks, it's best to ignore it.
 
nolimits67 said:
bucfanmike:
Temp change is a possibility. Come to think of it.. it hasn't rained in a couple of weeks and it stormed really good last night. It was quite humid and warm in the house this morning.

brycelarson:
This was a used tank that I got filled from empty. This is my first time using the tank, dual regulator, and Cornys. I put the kegs under pressure and practiced with water before kegging the beer. Didn't find any leaks anywhere. I am shooting for 2.7 vols of CO2.

While I'm on the topic... I've been trying to find a definitive answer (if there is one) on the topic of letting the beer age in the keg at room temperature purged of oxygen but not under continuous CO2 pressure.. or hitting it with constant pressure, chilled down before getting served, purging out CO2 and setting it at serving pressure.. I wanted to do a set and forget, but since I don't have a way to keep my kegs cold for the next few weeks I've just kept them under higher pressure (calculated by beersmith) to get it carbed up.

A few days before the wedding I'm planning to put the kegs in a fridge and get the kegs to 10PSI for serving. Can I just throw the kegs in the fridge still at 28PSI. When the kegs cool the pressure will drop right? Will this affect the carbonation? After this is done can I just reconnect my tank and set it at 10PSI?
Click to expand...

Or, since it appears you are letting them age a bit at room temp, you can use co2 just to seal the lid after adding priming sugar and let them natural carbonate. You use less sugar this way, however, so you'd want to consult a carbonation calculator
 
phoenixs4r said:
The high pressure gauge doesn't work properly on CO2 tanks, it's best to ignore it.
Click to expand...

That's not a fair statement. It works fine, it just doesn't give you as much information as it would for a compressed gas.

OP, CO2 is stored as a liquid in the tank and it boils off to maintain pressure. The pressure is only a function of temperature as long as there's some liquid left. Once it's all evaporated, the gauge will drop relatively quickly as the remaining gas leaves the tank.

This wikipedia page tells you the relationship between temperature and vapor pressure for liquid CO2:

http://en.wikipedia.org/wiki/Carbon_dioxide_data#Liquid/vapor equilibrium thermodynamic data

If the tank still has liquid CO2 in it (weighing it and subtracting the tare weight is the only way to tell), this chart tells you your tank should be at around 66 degrees F to get a pressure of ~800 psi (=5515 kPa).

:mug:
 
nolimits67 said:
it seems to have dropped from a little under 850PSI to a little under 800PSI.
Click to expand...

this is a natural amount of fluctuation. a 50psi drop in tank pressure is roughly the same as a 4 degree drop in temperature (~73 > 69).
 
Thanks for all the input. Took another reading and it's back to where it was. Still paranoid after my 7th brew... Good thing is I still don't have a reason to be.
 

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