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General Category => Equipment and Software => Topic started by: jimrod on April 16, 2012, 07:35:04 AM

Title: volume gauge
Post by: jimrod on April 16, 2012, 07:35:04 AM
Is there a piece of equipment that can measure the volumes of CO2 in the keg? For me there is a fine line between under carbed and foamy. I can't seem to get it perfect.
Title: Re: volume gauge
Post by: bluesman on April 16, 2012, 10:19:33 AM
The best method to measure this is by measuring the keg head pressure.  You can monitor the pressure and adjust as necessary. Here's the gage.

(http://3.bp.blogspot.com/_hTiyKn1_3Fw/SkrSmlQUjII/AAAAAAAAD2Q/WSiVs-lLoBM/s400/bleeder.jpg)

http://www.northernbrewer.com/shop/bleeder-valve.html

Title: Re: volume gauge
Post by: PSUhomebrewer on April 16, 2012, 10:20:06 AM
They do sell a keg pressure gauge but since volume is dependent on 2 things (temp and pressure) probably not. If you want, make sure you have a thermometer in the fridge with the beer so you can get a good temp reading. You could try attaching a valve stem to the end a hose and Che k the pressure to make sure the regulator is functioning properly.
Title: Re: volume gauge
Post by: bluesman on April 16, 2012, 10:34:10 AM
They do sell a keg pressure gauge but since volume is dependent on 2 things (temp and pressure) probably not. If you want, make sure you have a thermometer in the fridge with the beer so you can get a good temp reading. You could try attaching a valve stem to the end a hose and Che k the pressure to make sure the regulator is functioning properly.

I should have mentioned that...

(http://cdn.homebrewtalk.com/attachments/f13/12762d1251573584-crash-cool-then-bottle-volumes-chart.jpg)
Title: Re: volume gauge
Post by: jimrod on April 16, 2012, 01:39:46 PM
So if you beer style calls for 2.7 volumes per liter, what is the static psi measurement?
Do you first purge the keg then shake a little to get the measurement?
Then the static psi measurement for 2.7 volumes at 40 degrees is 14 psi and the gauge should read 14 ?
Title: Re: volume gauge
Post by: a10t2 on April 16, 2012, 01:40:07 PM
There are purpose-built devices too: http://www.zahmnagel.com/Products/tabid/57/Default.aspx
Title: Re: volume gauge
Post by: rjharper on April 16, 2012, 05:04:36 PM
So if you beer style calls for 2.7 volumes per liter, what is the static psi measurement?
Do you first purge the keg then shake a little to get the measurement?
Then the static psi measurement for 2.7 volumes at 40 degrees is 14 psi and the gauge should read 14 ?

If you set the regulator at the target psi and let it come to equilibrium, then you'll be set,and  you'll have the volumes you want, assuming your temp is correct and your serving lines are balanced for that pressure. I'm not a big fan of the "crank it up for 24hrs then bleed off" approach. I can wait a week...
Title: Re: volume gauge
Post by: tomsawyer on April 16, 2012, 05:52:14 PM
So if you beer style calls for 2.7 volumes per liter, what is the static psi measurement?
Do you first purge the keg then shake a little to get the measurement?
Then the static psi measurement for 2.7 volumes at 40 degrees is 14 psi and the gauge should read 14 ?
You need to pressurize it according to the temp you are storing it at.  In other words if you are carbing at room temp then set the pressure for that temp, if it is in the fridge then set it based on that temp.

So if your beer is sitting at 66F you need to put it on 29psi for several days for it to carb to 2.6vol.  When you refrigerate it is still 2.6vol.  The lower temps mean you don't need as much pressure to accomplish the same vol CO2 since gas is more soluble in liquid at lower temps.
Title: Re: volume gauge
Post by: tomsawyer on April 16, 2012, 05:54:51 PM
You can purge the keg to get rid of air initially, but you have to leave the gas on the beer for several days before it reaches equilibrium.  I will often charge the keg and take the gas off, then the next day there is no pressure in the keg because all the gas dissolved in the beer.  Its takes several days of doing this befor ethe keg actually holds pressure.  You can speed it a little by shaking/rolling the keg so more of the surface area of the beer is exposed to the gas.