Regulator Pressure

[burning_snowmans]

I put my first pin lock keg on CO2 last night at 10psi. Right now the keg is not in my keezer so it is warm, but I wanted to get a head start on carbonating while I got the keezer cleaned up.

After setting the pressure and making sure there were no leaks I came back to check the keg after a few hours and my CO2 line pressure was down to 0. I opened the regulator up a little bit to get the pressure back up to 10 and left it over night. This morning the pressure had dropped to 5, so I opened it up back up to 10 again.

I have a few questions:
1. What exactly is that gauge measuring? Is it the difference in pressure between the keg and the line? and if so, does that mean the two are equalizing?

2. Is this a typical problem with low end regulators? My regulator is a Kegco double regulator that came with a conversion kit, so it is not the most high end option.

Thanks!

 

[brittney81895]

Someone probably has a better, more detail explaination,but.... Sounds like you have a leak somewhere. Did you check all of your connections with soapy water? Try turning it up to 20psi, shake the keg til you hear the CO2 going into the keg. Then check the connections with soapy water again. If you don't have a leak you could have a faulty regulator!?! Good luck!

 

[brittney81895]

Yeah, after reading your post again....probably not a leak... I would try 20psi for at least 24 hrs at the same temp. Can you bring the regulator to where you get your tank filled to see if they can test it? Sorry, I haven't been any help! Again, good luck!

 

[doug293cz]

The low pressure gauge measures the pressure difference between the low pressure side of the regulator and atmospheric pressure. It is actually a differential pressure gauge.

The regulator has a needle valve bonded to a diaphragm. One side of the diaphragm is exposed to the keg (manifold) side of the gas system, and the other side is exposed to the atmosphere. There is a spring with adjustable compression on the atmosphere side which allows additional force to be applied to the atmosphere side of the diaphragm. When the force on the diaphragm from the atmosphere + spring is greater than the force from the gas manifold, then the needle valve is forced open, allowing more gas into the manifold, thus raising the pressure in the manifold. When the pressure in the manifold gets high enough that the force on the manifold side of the regulator is higher than the other side, the needle valve is forced closed, so that no more high pressure gas can enter the manifold. This all works as a feedback controlled mechanism to keep the manifold pressure constant, with the equilibrium pressure determined by the compression of the spring in the regulator.

If you have high pressure CO2 in the tank, and the valves are all open, but the pressure isn't staying stable, then the regulator is malfunctioning. The needle valve could be sticky, the spring could be worn out, or it could be some other problem.

Many regulators have rebuild kits available for them. If you can find one for yours, then rebuilding the regulator could get it working correctly again. Otherwise, you should probably get a new regulator.

Brew on

 

[burning_snowmans]

Thanks Doug, thats exactly the sort of information I was looking for. Over the last 24 hours the pressure has stabilized which is great news, but now I worry that the 10 psi shown on the gauge might not be whats actually being applied to the keg if the regulator is faulty. Would the temperature of the CO2 in the tank effect the low line pressure? I know it would change the tank pressure. What I'm thinking here is that the tank was newly filled, and slowly warming up while I was pressurizing the keg. As the tank warms the pressure changes creating the effect of the low line pressure dropping. Am I completely out in left field on this one?

 

[doug293cz]

Thanks Doug, thats exactly the sort of information I was looking for. Over the last 24 hours the pressure has stabilized which is great news, but now I worry that the 10 psi shown on the gauge might not be whats actually being applied to the keg if the regulator is faulty. Would the temperature of the CO2 in the tank effect the low line pressure? I know it would change the tank pressure. What I'm thinking here is that the tank was newly filled, and slowly warming up while I was pressurizing the keg. As the tank warms the pressure changes creating the effect of the low line pressure dropping. Am I completely out in left field on this one?

The gauge is independent from the regulator, so if the regulator is acting up the gauge will still read the actual pressure on the keg (low pressure manifold) side. If you suspect the gauge is reading incorrectly, they are relatively cheap and easy to replace.

The CO2 tank pressure should not affect what's happening on the low pressure side. The purpose of the regulator (when working correctly) is to maintain a constant pressure on the outlet side, independent of the tank pressure.

Brew on