Odd 4-Way Secondary Regulator Behavior

[r757chandler]

I've had a few CO2 tanks go too quickly and I think I've narrowed it down to my secondary regulator. I have a Taprite 4-way and I believe the model is T1694ST. If I turn off all four of the shut-off valves on the secondary regulator and turn off the one on the primary regulator (also Taprite), wait a bit, and then open the shut-off valve on the primary I hear it re-pressurize the secondary.

The #4 regulator on my secondary I believe to be faulty. It believe it doesn't seal correctly so the pressure will increase over time to well past what it is set to (I learned this by over-carbing a keg a while back.) That shut-off valve has remained closed since, but I've been experimenting a bit and it is currently reading about 25 psi. The #1 and #3 regulators are both set to roughly 16 psi and I have been using them with no issues to serve kegs of beer (yeah, that's a little high for beer, I'm testing slightly different pressures.) The #2 regulator I use to make soda water, so it is set to around 36 psi.

I originally suspected my soda water setup to be the culprit, so I've always left that check valve closed unless I'm making soda water. All that setup is is a short gas line leading to a gas ball-lock quick-disconnect that I can connect to a carbonation cap. This might leak too since I hear the line re-pressurize when I turn on the shut-off valve, but that shouldn't be a significant source of CO2 loss since I never have that shut-off valve open for more than about 30 seconds at a time, I wouldn't think.

Here is where I get a bit confused. I have noticed is that when I shut everything off the pressure for the #2 regulator (soda) will slowly drop over time to match that of the #4 regulator (faulty). It has done this for two different settings on the #4 regulator so it doesn't seem to be a coincidence. The #1 and #3 pressures are never affected, though I haven't tried to set the #4 pressure below 16 psi yet.

Any thoughts? Sorry for the long post but any help will definitely be appreciated. Thanks.

 

[tll77]

I think you're on the right track.
I would look into rebuilding reg#4, taprite rebuild kits are available.

 

[r757chandler]

Thanks, I've thought about doing that anyway because I would like them all to work correctly. And if that fixes it then great but it has piqued my curiosity do I'd still be interested in knowing what exactly is going on.

One thing regarding rebuilding is that I haven't figured out where to begin taking it apart. Does anyone have some instructions? I've seen instructions for the metal screw but it's the one with the plastic cap. Does it just pop off with some force? Thanks.