Keg regulator in red zone straight away

[benoj]

Hi there,

I kegged my first batch today and hooked up my co2 equipment for It’s first spin.

Initiallu I head a couple of leaks so went and tightened the setup with my spanner and all seems fine.

My regulator rear 50 bar when I first plugged it in. I’ve put it in my fridge around 4c and I’ve noticed the pressure reading dropped down. I wouldn’t expect the has to be going down this quickly (it’s a 7lb tank)

Is this drop to do with change in temp of the regulator - or should I be worried I have a leak?

 

[Mtrhdltd]

The drop is probably just temperature. I used to freak out a little too before I moved the bottle out of the kegerator. A bottled gas changes pressure quite a bit with temperature changes.

 

[day_trippr]

Very strong relationship between CO2 vapor pressure and temperature. Lesser effects due to % of total fill volume...

Cheers!

 

[doug293cz]

In a cylinder with any liquid present, the pressure is determined solely by the vapor pressure of CO2 at the temperature of the cylinder. Once the liquid is gone, then the pressure is determined more by how much CO2 gas is in the cylinder, and to a lesser extent by the temperature. The horizontal portions of the lines in the chart above show the tank pressure at various temperatures when there is liquid in the cylinder. For temps above 87° (30.5°C) things get "weird" (super critical phase behavior.)

Brew on

 

[doug293cz]

Damn it! @day_trippr types faster than I do (and isn't as long winded.)

Brew on

 

[benoj]

Ah cool thanks guys - yep pressure seems to be remaining stable.

So if I’m looking at this correctly -pressure dropped by about half because temp dropped from around 24c (75f) to 5c(40f) This should remain stable until around 15% at 5c (40f)

 

[rsquared]

Ah cool thanks guys - yep pressure seems to be remaining stable.

So if I’m looking at this correctly -pressure dropped by about half because temp dropped from around 24c (75f) to 5c(40f) This should remain stable until around 15% at 5c (40f)

Yeah, from about 950 psi (65 bar) to 550 (38 bar) at those temps. I just double checked my regulator, and the red zone starts down at 30 bar, so I blame your regular starting it at 40 for scaring you...