[Al Skierkiewicz]

So you are using an off board compressor? If after you close the valve, the high side pressure falls, then you have a leak somewhere. It could be on the low pressure side since the regulator will keep supplying 60 psi until the high side falls to 60 psi. Let it sit and watch what happens. You have a leak somewhere. The system components can usually hold pressure for several minutes to an hour or more with no leaks. Use the soapy water technique. Mix some liquid soap into water and wipe on to all the joints. A leak will produce bubbles when you add the soap solution to the joint. This could be a threaded joint or a hose fitting. On rare occasions the vent valve can leak but it is very rare.