Keezer and pressure changes - temperature or slow leak?

[mirthfuldragon]

I bought a used keezer a couple of weeks ago. I cleaned everything, and swapped out a four way manifold for a brand new four body Taprite secondary regulator with check valves (mounted inside the keezer). I am trying to figure out if I have a leak. The keezer is located in my detached garage. The 20# CO2 tank is outside the keezer, through the collar, feeding the four body regulator.

Last night at 8pm, I set the primary regulator to 30 psi and set the secondaries to 20 psi, turned off the tank, turned off the primary shutoff valve, and turned off the secondary regulatory shutoff valves. This morning, after ~12 hours, the tank primary regulator is showing 34 psi and the secondaries are showing 15 psi. Yesterday was relatively hot, about 85°, and overnight the temperature dropped to 67°, where it was when I checked it.

Do I have a leak somewhere, or is that fluctuation a change normal for an external tank subject to temperature fluctuations?

 

[IslandLizard]

Could be due to temp fluctuations, sure.
More likely, there's such a tiny amount of gas inside the regulators and tubing, a very, very small leak anywhere in the system, left over those 12 hours, will drop that residual pressure relatively fast. But nothing to really worry about. We may waste more in one single keg purge than that tiny leak does in a month or year.

I wish someone devised an easy method to detect small (and bigger) leaks in the gas system.

I sorta found by chance, having a long hose, from the main regulator going to the manifold, with a few leftover drops of Starsan in it, when draped in a sagging U-shape, it will show any gas going through by bubbling through that little bit of liquid in the bottom of that U. Similar to how an S-shaped airlock works. Yup, I should probably patent that idea.

 

[mirthfuldragon]

I have been fiddling with it and keeping notes, and I still have no idea. I am going to keep tinkering for now. Regardless, the leak is very slow so it is probably a non-issue.