Regulator leaking pressure?

My Keg setup has a 5lb CO2 canister going straight into a primary regulator, which then flows into a 5-way secondary regulator that distributes CO2 to 5 different kegs.

Yesterday I had a leak that I was trying to diagnose. So I pressured up everything, and then closed the valves from my primary regulator to secondary regulator, and between each secondary regulator and their respective 5 kegs.

I wake up this morning and all of the regulators have held pressure overnight except the center secondary regulator which has fallen from 20 psi to just under 10psi.

When I opened the primary regulator valve, it filled up super fast back to 20psi.

What does this loss of pressure in my center secondary regulator mean? Where could a leak be?

Most likely the connection between that regulator and its shutoff valve. Try removing it and doubling up on the pipe tape.

ooo -- good call, i'll try that today. Thanks David!

the most difficult leak to find...is inside the regulator. If you put a little bit of soap solution on the weep hole of each of the regulators...does that one bubble more than the others?

Inside the regulator there is some type of vavle that allows pressure to go from the High side to the low side. If this leaks...you'll vent gas out the weep hole. It also can cause the regulator setting to creep from it's original set point.

If your regulator uses a "capsule" vavle seat...it could be loose or faulty...

http://www.micromatic.com/draft-keg-beer/regulators-parts-pid-8402.html

If your regulator uses a poppet valve (imi cornelius) it could be a bad poppet or the mating surface. The mating surface is pressed into the brass body...it has a thin o-ring that makes a seal. Sometime this seal leaks... With an IMI Cornelius regulator...if you unscrew the set screw to drop the pressure to zero...and take the front cover off (4 -screws)...you'll see the poppet in the center of the regulator body. With the tank valve ON...there should be NO gas coming through the poppet with the face of the regulator removed. Test it with soap solution. If the poppet leaks...you can get a new one in a rebuild kit. If the seat mount leaks (were the silver colored valve seat meets the machined brass regulator body...you're probably out of luck. You may be able to press it out carefully, apply some NSF silicone sealant to it, and press it back into place. If it deforms at all...it'll never work again)

Note: if you have an IMI cornelius regulator...there IS a difference in the rebuild kit for a Primary regulator and a secondary regulator...make sure you get the correct one.

oh man, that looks like a headache....

They're actually very easy to work on. The only pain is that most manufacturers use thread sealant...and it takes a bit of force...or little bit of heat applied to the joint to unscrew it. And remembering to look out for LEFT HAND THREAD fitting on the High Pressure fittings (some regulators)