Pressure loss but no bubbles?

[u4ia]

the answer to this question may be really obvious, but its got me scratching my head and I just dont get it! maybe I need more coffee? :11:

Setup= Apeks DS4 first stage, AL Legend (the octo with only the vane adjustment), and SPG. When I pressurized the setup and turn it off the tank valve it slowly loses pressure (the gauge drops ~100 psi every few minutes.) I dont see any obvious loss of air from any of the connections. no visible bubbling. between dives I swapped the second stage and checked the hoses were tight, but it still happened however, pressure dropped *seemed* slower. or it could have been my imagination.

any ideas what would cause this without bubbles?

 

[Fishpie]

It has to be leaking somewhere.
If it is a yoke set my first choice of culprit would be the tank o ring.
Next pressure gauge air spool o ring.
Then 2nd stage swivel.

I assume it is not leaking out of the mouthpiece.

 

[Web Monkey]

the answer to this question may be really obvious, but its got me scratching my head and I just dont get it! maybe I need more coffee? :11:

Setup= Apeks DS4 first stage, AL Legend (the octo with only the vane adjustment), and SPG. When I pressurized the setup and turn it off the tank valve it slowly loses pressure (the gauge drops ~100 psi every few minutes.) I dont see any obvious loss of air from any of the connections. no visible bubbling. between dives I swapped the second stage and checked the hoses were tight, but it still happened however, pressure dropped *seemed* slower. or it could have been my imagination.

any ideas what would cause this without bubbles?

It's either leaking or cooling off.

I don't know any other way to find the leak, except to put it underwater and watch for bubbles.

Terru

 

[u4ia]

meant to mention its a DIN reg
I know its gotta be leaking, but wouldnt I see it?

 

[redacted]

It could just have been a tank valve o-ring that didn't seat right until it was jostled around a bit making the "leak" disappear. I'm fairly hard of hearing so I run that leak test almost every dive, especially with dive op tanks. The slow leak is fairly common and usually cured by fiddling a bit with the first stage. Sometimes it requires a new valve o-ring.

 

[Nemrod]

As well, it could be the HP seat. Check your IP and see if it rises as your spg falls.

The small leak you are looking for would present itself as only a very few tiny bubbles over several minutes or an inaudible leak at the HP or LP seats.

Is this a new regulator or an old regulator?

N

 

[Fishpie]

Do you have the BC inflator hooked up?
If so it could be leaking into the bladder....no visible bubbles.

 

[Teamcasa]

the answer to this question may be really obvious, but its got me scratching my head and I just dont get it! maybe I need more coffee? :11:

Setup= Apeks DS4 first stage, AL Legend (the octo with only the vane adjustment), and SPG. When I pressurized the setup and turn it off the tank valve it slowly loses pressure (the gauge drops ~100 psi every few minutes.) I dont see any obvious loss of air from any of the connections. no visible bubbling. between dives I swapped the second stage and checked the hoses were tight, but it still happened however, pressure dropped *seemed* slower. or it could have been my imagination.

any ideas what would cause this without bubbles?

If the pressure drops, you have a leak.

Do you have the BC inflator hooked up?
If so it could be leaking into the bladder....no visible bubbles.

That's where I would look first.

 

[u4ia]

thanks everyone for all the ideas.

there is nothing else attached to the first stage - only the SPG and regulator.

I will recheck all the o rings and connections and try again.

the first stage is new this year, not too many dives on it - will check the IP.

 

[Nemrod]

If it really is NOT leaking at the spg spool or spg to first stage O-ring and is not leaking at the tank O ring (DIN or yoke) and the second stage hose is not leaking at any connections and there is no BC hose and all of the port plugs are not leaking then your down to HP and LP. Since the leak did not stop when you switched second stages then I favor the HP leaking slightly and it is just inaudible to you since the leak is tiny, it has to be leaking to the second stage. The IP will rise as the spg falls (valve OFF), when the IP reaches set point it bleeds off through the second stage. Make sure the hose itself does not grow any bubbles on it, both LP and spg HP hose.

New regulators sometimes drift a bit and some regulators do not have good first stage lock. Your Legend should lock up and have a solid readout on the spg for at least 30 minutes.

N