Northwest Dive Club

Ok, this is a new one for me. I was diving on my steel 100 din tank with my Apex regulators. Did my first dive came out, turned off my air. Went to do my second dive, turned tank back on (without touching anything else) and my computer read 0 (cobra intergrated). I still had 2500 lbs left in my tank from the last dive, I checked before I turned it off. The hose was not pressurizing at all. So I checked and the inflator hose, second stage and octopus were all giving me air. So, I switched to the other HP port and turned the air back on, still nothing. So my husband put his set on the same tank and his read 0 as well even though all the LP ports were delivering air. After we switched tanks all our gear was working correctly.
Isn't this the strangest thing ever? Has anyone had a tank valve fail this way? Shouldn't it have read at least 130psi or so?
I called the LDS and told me this was not possible... lol
Certainly strange but? Anyone?

Cera wrote:Ok, this is a new one for me. I was diving on my steel 100 din tank with my Apex regulators. Did my first dive came out, turned off my air. Went to do my second dive, turned tank back on (without touching anything else) and my computer read 0 (cobra intergrated). I still had 2500 lbs left in my tank from the last dive, I checked before I turned it off. The hose was not pressurizing at all. So I checked and the inflator hose, second stage and octopus were all giving me air. So, I switched to the other HP port and turned the air back on, still nothing. So my husband put his set on the same tank and his read 0 as well even though all the LP ports were delivering air. After we switched tanks all our gear was working correctly.
Isn't this the strangest thing ever? Has anyone had a tank valve fail this way? Shouldn't it have read at least 130psi or so?
I called the LDS and told me this was not possible... lol
Certainly strange but? Anyone?

Did you have an analog gauge handy? If not gauge it at the shop when you take it in.

It may be that it leaked down to a very low amount during the SI (below the digital sensor's accuracy band, 200psi?) and so while the reg was giving air, there really wasn't enough to register on the digital sensor. Only thing I can think of.

We turned the tank on and let it run, there was lots of air in it. More than enough to register.

Cera wrote:We turned the tank on and let it run, there was lots of air in it. More than enough to register.

Then I got nothin'. Sorry. I'm not that familiar with digital SPG's. It's odd that 2 independent 1st stages and SPG systems BOTH read 0 on that tank, but were fine on a different tank.

I'd be suspicious of the cobra, I guess. It does sound sort of impossible, from your description, though. Have you been able to duplicate this failure?

The entire Line was not pressurizing... not just the console. When you turn air on you can feel the line fill with air, it was not doing that. I know it seems impossible. We haven't re-tried yet, we don't have the tank right now.

maybe there's debris in the tiny orifice of the HP line?

Cera wrote:The entire Line was not pressurizing... not just the console. When you turn air on you can feel the line fill with air, it was not doing that. I know it seems impossible. We haven't re-tried yet, we don't have the tank right now.

Maybe try pressuring the first stage with the cobra disconnected to see if gas comes out of the port? If it does, maybe you have some blockage in the Cobras hose?

I would put both regs on your husband's tank. If they both operate and read the same pressure then there is a chance the first tank is very close to empty.

Having just replaced my HP hose, it has a stinking small hole in the end that could become plugged in a heartbeat. I'd check the hose.

To clarify, I used the entire set-up on a different tank, and it worked fine. It was just this tank. My husbands set-up did the same thing, on the same tank, (read 0). I also know there is still lots of air in the tank.
I told you it was strange. We will put an analoge gauge on when we get the tank back. But still?
Thanks for the discussion, it is just really vexing us. I was hoping someone else has had this specific problem with at tank valve failure.

How long was your first dive? 2500 lbs seems like a lot to have left over.

My money is on the tank not being as full as you think it is.

It was only a 20 minute dive to 40 feet. I started with 3500psi.

i would take ever thing in and have it all tested befor the next dive better safe then sorry

I just had my reg's serviced a few months ago, so I sent it back in and the checked them, everything is working normally.

So, Just to clarify your tank is only delivering low pressure air? you sure it has more than 200psi or so in it? the regulator in question works perfectly on any other tank?

Could it be possible that when you depressurized the reg to put it on your buddies tank, the pressure in the hose cleared something plugging the orifice in the HP hose? It just doesn't make any sense that it could be the tank valve. If gas was passing to the lp side of the reg, it would have to go by way of the HP side.

Cera I agree with others who've guessed at an obstruction in the HP flow - either at the regulator end of the hoses or inside the regulator itself. Do you habitually open tank valves to clear water/debris before attaching your first stage? It could be that the "bad" cylinder had some junk sitting in the mouth of the tank valve and it was blown through to block an orifice in the first stage's high pressure chamber or at the regulator end of the computer's hose. Another possibility is that the cylinder has some debris in it - did you invert it during that first dive? The dip tube is supposed to reduce the likelihood that an object in the cylinder will block flow at the valve but it's not guaranteed (I've opened up used cylinders I've bought to find the dip tubes completely missing from the valve). Finally, it seems possible that you and your husband's first stages could both be faulty - perhaps there was an assembly error when they were last serviced and something is blocking that internal HP passage when certain conditions are met. Unlikely, I know - but if it were me I'd be treating those regulators with some suspicion until a solid resolution is found for the odd behavior.

We also assumed it was the first stage, since it was so bizzare. WE assumed that it was the HP ports of my first stage. But when my hubands did the exact same thing we were sure it was NOT the first stage, especially since all of the LP ports were working. Like I said, I had the reg's looked at after the problem, it is NOT the first stage or the HP or LP ports. All of the regs, computers, hoses work on another tank and were tested by a service rep at a dive shop.
If we were to assume it were an obstruction, wouldn't that stop all the air? My best guess it that it is an obstruction, because besides that I have nothing.
I was wrong before, at the end of my dive I had 2930psi left in the tank, not 2500 as previous stated, I checked the computer.
SO can we please assume that the tank is full. Otherwise this would be called the worlds stupidest problem, lol..

Cera wrote:
SO can we please assume that the tank is full. Otherwise this would be called the worlds stupidest problem, lol..

Not until you have that tanked hooked to an analog tank gauge and confirm it. Never assume, verify.

Ya, the ONLY way I can see this problem could happen the way you describe is a tank under 200psi, sure, obstruction blah blah... I don't think so myself. if it was an obstruction I don't think it would have prevented the "PSI" from regestering while alowing LP flow, valves don't work that way that I am aware of. Seeing as how you tested it on 2 different reg set up's it's tank presure... Occam's razor and all that...

You dove the tank and your SPG worked ON THAT TANK on the dive right?
You get out shut off your air, turn it back on and it reads zero.
hubby hooks up his reg's and the SPG reads zero.

you put your regs on another tank and it reads appropriately
hubby puts his regs on same tank and it reads appropriately

back to original tank and both reg's read zero.

Is that right?
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If it is...
Sorry but I'll bet you a beer the tanks empty. I drink Root beer BTW!!

An obstruction of the HP port will not typically impede the LP side of the reg.

your cobra can IIRC be set to have a higher threshold than 200 psi... I could be mistaken. It's been a long time since I owned one.

but let us know what you find out Cera... this is most interesting.

Waynne Fowler wrote:You dove the tank and your SPG worked ON THAT TANK on the dive right?
You get out shut off your air, turn it back on and it reads zero.
hubby hooks up his reg's and the SPG reads zero.

you put your regs on another tank and it reads appropriately
hubby puts his regs on same tank and it reads appropriately

back to original tank and both reg's read zero.

Is that right?
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Logic WIN

Peter has a Cobra that I'm sure you can try for a 3rd opinion! Too bad he's in Woodinville...