Is it unusual

[Kharon]

Is it unusual for a second stage still attached to the first stage, under pressure and not purged, but pressure shut off, to leak down to zero - either short or long?

If so - possible causes?

 

[tbone1004]

it's not abnormal. Typically it is a very small leak somewhere in the lines. Could be in a myriad of places. The speed that it drains is obviously relative to the leak. Mine will all go overnight with no problem but haven't tried more than 24 hours.

 

[Scuba Scott]

possible causes?

I would suggest putting the whole thing under water and looking for bubbles and this will be the source of your leak.

What equipment do you have? Some 1st stage regulators leak a tiny bit of air as their normal operating condition.

 

[207diver]

Any drop in pressure would indicate a leak it may be small enough that you are unable to hear it. Like the last reply said submerge the whole unit in the water and check for a very small 2nd stage leak, hose leak, or possibly even a leak at your power inflator or drysuit QD.

 

[redacted]

[I see such a leak fairly often when on dive trips. The culprit is usually the tank valve o-ring. A twist of the pressurized 1st stage often stops the leak.

BTW, my hearing is poor so I often can not hear such a leak. After setting up my gear, I pressurize it and then turn the valve off and observe the SPG.

 

[redacted]

Oops.

 

[dumpsterDiver]

I can "hear" you fine, you don't have to shout or repeat yourself...

One of the more innocuous (potential) leaks is the O-ring where the hose connects to the regulator. You won't detect it unless submerged and still it can be very fine bubbles.

 

[oldschoolto]

If the regulator set holds pressure over night, Not a big deal... If the o-ring in a swivel is just right , It may just leak a little bit.. Turn the hose and it'll hold pressure fine.. I bubble check all my regulator sets, It's really the best way..

Jim....

 

[Kharon]

Will try. The reg is a Hollis 500SE.

When I surfaced and took the reg out of my mouth yesterday there was a distinct hissing. Didnt think to submerge it then. Back at the apartment I hooked it to another tank and no hissing but pressure dropped very, very slowly when valve shut off. Putting the reg under water this morning and no bubbles. Still the slowest drop in pressure when pressurized with valve then shut off. Maybe 100 psi in 5-10 minutes.

 

[tbone1004]

that's pretty quick but that regulator is known for leaking so it's unlikely you'll be able to get it much better than that