Strangest equipment failure ever!

[Dashrynn]

My guess is that the tank was empty.

you always view everything negatively, its barely full.

[airsix]

I think we simply have a failure to communicate. My fault for not being specific regarding the use of "empty" regarding diving cylinders. When we say empty we mean any pressure below several hundred psi. So when I say a tank is empty I mean there is less than 500psi remaining because it's not safe or reliable to use below that. 200psi is typically enough pressure to operate a regulator and not register on some pressure gauges. It's still plenty of pressure to make a scene when you crack the valve open with no reg installed.

[Geek]

My guess is that the tank was empty.

you always view everything negatively, its barely full.

[Nwbrewer]

Now that 3 gauges are all reading empty (1 analog) I'm starting to lean towards massive obstruction in the valve, enough to let 130-150 PSI of gas through, but not enough to let much more than that through. You could leave it hooked up overnight and see what happens. I'd be inclined to have it VIPed and the valve checked at this point. Can't hurt and it's not all that expensive.

The other thing you could do to avoid any more speculation that the tank is empty is throw it on a scale. The empty weight should be published somewhere.

[Sounder]

I think we simply have a failure to communicate. My fault for not being specific regarding the use of "empty" regarding diving cylinders. When we say empty we mean any pressure below several hundred psi. So when I say a tank is empty I mean there is less than 500psi remaining because it's not safe or reliable to use below that. 200psi is typically enough pressure to operate a regulator and not register on some pressure gauges. It's still plenty of pressure to make a scene when you crack the valve open with no reg installed.

Yes, near-empty. It could have a bit of pressure inside, along with some water, some corrosion flakes stuck in the dip-tube... and, of course, a taco.

[Waynne Fowler]

I downloaded my computer, it said there was 2930 when I turned the air off at the end of the first dive.

What kind of beer would you prefer Cera...... Thomas Kemper's Private Reserve, Mug Old Fashioned or ???????

I really expected you to download the puter and find you'd exited with 293psi not 2930....
While it's possible for the tank to drain 2k on a divesite.... it's not so likely that it would have went unnoticed unless it had been sitting for a VERY long time with an unnoticeable trickle of air.
The only simple thing left IMO is that you have, just what you and others suggested in the beginning... an obstructed valve.

Don't take it personal Cera when folks question your conclusion, there were several possibilities to check out. It's not uncommon for people to believe they exited with more air than they actually did.... it's really very common. It's not uncommon for folks to have a gas leak on site that they didn't hear. Folks are just drawing conclusions based on what they knew of the situation and their past experiences. And without the equipment right here in our hands the best we can do is 'guess'...

Having a valve plug up at that time is really rather odd IMO. But I guess if it's gonna jam up, then was as good a time as any... the valve don't care when it fubar's. I'm glad it didn't happen underwater, though it probably wouldn't have been a life threatening issue providing you and your bud's are competent with and OOA situation..... in deeper water you probably would not have been able to draw enough air out of it for a breath, in the shallow's it may have just breathed hard. It unquestionably would have led to at least an "Oh CRAP" moment!

I hope you keep us posted on what they find with the valve, but I'm satisfied that you identified the problem from the very beginning. Thank you for posting it and allowing us to play with it. I hope we didn't hurt your feelings while trying to get to the bottom of it, but we have to dance all the way around the problem to get a good view of it from all sides. And unfortunately that meant calling your conclusion into question.

I'm personally satisfied that you had it right all along.... goood job Cera!!!!! BTW: I expect you to collect on that beer. Do let us know what the shop finds out when they open that thing up.

[airsix]

Cera indicates she can breath off the regulator. Therefore the valve is providing adequate flow. You can't have this much flow and not have the high-pressure side of the regulator reach equilibrium with tank internal pressure. You can't bypass the SPG and still get pressure off the LP side and you can't blame the SPG because multiple regulators verify the same result. If the evidence we've been given is correct (can breath off the reg and multiple SPGs read zero) and that tank has more than 300spi in it you can change my username to benisamoron.

Edited to add: This being the internet and all it might sound like I'm being a turd. I'm totally not (trying). NWDC is my happy place and I'm just curious to unravel this mystery. Cera, I hope we could be friends and that I have not been a source of frustration in my attempt to get to the root of your dilemma. That goes for everybody else too.

[CaptnJack]

3 gauges say empty or won't pressurize at all now?

[Geek]

Cera indicates she can breath off the regulator. Therefore the valve is providing adequate flow. You can't have this much flow and not have the high-pressure side of the regulator reach equilibrium with tank internal pressure. You can't bypass the SPG and still get pressure off the LP side and you can't blame the SPG because multiple regulators verify the same result. If the evidence we've been given is correct (can breath off the reg and multiple SPGs read zero) and that tank has more than 300spi in it you can change my username to benisamoron.

Edited to add: This being the internet and all it might sound like I'm being a turd. I'm totally not (trying). NWDC is my happy place and I'm just curious to unravel this mystery. Cera, I hope we could be friends and that I have not been a source of frustration in my attempt to get to the root of your dilemma. That goes for everybody else too.

Just put my reg on a tank that has 259psi and breathed fine with my Hog....... benisamoron

[LCF]

Being a linear thinker and an ex-mathematician, I find Ben's analysis compelling.

But one thing to mention . . . we deal all the time with tanks with 2 or 3000 psi in them, so 150 psi seems like almost no pressure at all. But . . . 147 psi is TEN atmospheres. It's also above the intermediate pressure on a regulator, so it's enough to get LP hoses to fill and operate second stages. 150 psi in an Al80 is 3.75 cubic feet of gas, which isn't very much underwater, but if you're breathing regs on the surface to test them, and your SAC rate is around .5, you're going to have to breath for at least thirty seconds to drop the pressure below the IP. Thirty seconds is a surprisingly long time, and I doubt anybody testing regulators sits there and breathes for that long.

Three gauges reading zero seems to me to be far more likely to be an empty tank than some weird valve malfunction. But I could be wrong, and I'll cheerfully eat crow if it turns out to be something bizarre with the valve.

[airsix]

If the evidence we've been given is correct (can breath off the reg and multiple SPGs read zero) and that tank has more than 300spi in it you can change my username to benisamoron.

Just put my reg on a tank that has 259psi and breathed fine with my Hog....... benisamoron

Now I know you might be eager to call me a moron, but not so fast. I'm not disputing that you can breath off a tank at that pressure. In fact I'm confident you can. I'm saying that if Cera's tank has more the 300psi in it you can call me whatever you want. Like LCF is saying, you ought to be able to breath it down to something in the neighborhood of 135-150psi on the surface. But at those pressures the SPG isn't likely to register anything.

[CaptnJack]

Take the tank in question in for a fill. That will be gauge #4 to try.

At some point you gotta believe the gauge(s).

[Mattleycrue76]

What Ben said. Cera, I don't see anyone here trying to be anything other than helpful in trying to help you solve your mystery. We can only use logical reasoning using the information you provided. The fact that this thread wasn't hijacked two pages ago clearly shows that people are interested in helping you find some answers. Let us know what you find out.

[Agent 47]

I cant speek for Waynne or Matt and their respective shops but I can say out of sheer curiosity I would gladly service your valve for free if you were inclined to bring it by my shop. And I would imagine they would as well.

[Waynne Fowler]

I cant speek for Waynne or Matt and their respective shops but I can say out of sheer curiosity I would gladly service your valve for free if you were inclined to bring it by my shop. And I would imagine they would as well.

Word! Just to see it, I'm really curious about this one. What shop you at A? I'll have to make a visit one day soon.

[Agent 47]

Im at Evergreen Dive, up in Everett.

[Cera]

Ok, I have calmed down.. It took almost a day! lol
Sigh, I understand you are trying to be helpful (sort-of). But I don't understand why you can't approach the problem from a different angle, like I asked. Obviously empty was a first thought when it read 0. But I am 100% sure there is over 500 lbs of air in the tank. Wow, 100% you ask? Yes 100%. Therefore, people telling me the tank is empty, doesn't in anyway help me try to find out what the ACTUAL cause is.
I just had the tank Hydroed last month. We also just had the reg's serviced last month. Inevitably whenever something gets serviced it causes a malfunction of some kind. So I fully expect some name changes and whatever else was promised earlier.. I do not however want to eat the taco, that is apperently lodged in the tank. Hum, taco flavored air, you could be on to something.
I have to suspect that there is an obstruction of some kind that is not allowing the tank to fully release air at a high enough pressure for the gagues to read. I don't have a way to fill it, nor do I have a way to read it that does not involve a regulator.
I could open the valve, let all the air out and crack the sucker open to check, but I want to take it to the LDS as is so that I can have someone to verify that there is air in the tank.. Then I will then force them, perhaps by sword-point, to get on here and tell you all that I may be crazy, but I'm not that crazy. I will then take it to a church and have the spirt of Bettylou released from the tank. I wonder if her voice is the one I hear in my head while diving? Hum, I sure will miss her. PEACE

[Agent 47]

Sorry If this has already been asked but, is it a J-valve?

[airsix]

I have to suspect that there is an obstruction of some kind that is not allowing the tank to fully release air at a high enough pressure for the gagues to read.

Cera, there is a problem with the physics of that statement. Rate of flow may be restricted (such as if the knob isn't turned fully to the open position), but even if a valve is severely restricting flow the pressure will fully equalize given enough time. And how could you breathe from the regulator if flow is restricted?

[Sounder]

Taco flavored air sounds delicious... it's got me craving bacon-flavored trimix.

[Nwbrewer]

I have to suspect that there is an obstruction of some kind that is not allowing the tank to fully release air at a high enough pressure for the gagues to read.

Cera, there is a problem with the physics of that statement. Rate of flow may be restricted (such as if the knob isn't turned fully to the open position), but even if a valve is severely restricting flow the pressure will fully equalize given enough time. And how could you breathe from the regulator if flow is restricted?

Last night I hooked up a tank and just BARELY cracked the valve. I could get the needle to start coming up long before I could get a breath....

[Cera]

Now you realize why this is so bizzare, we thought that the HP ports had failed. It's a din vavle, No "J's" in sight.

[whatevah]

I just hooked up an analog gauge and it didn't even register. HOWEVER, air still comes out of the LP ports... and I can turn the tank on (STILL) and get air coming out.

Was the mechanical gauge plumbed through one of the same 1st stages belonging to you or your husband? Or was it attached to a completely different 1st stage?

[airsix]

Last night I hooked up a tank and just BARELY cracked the valve. I could get the needle to start coming up long before I could get a breath....

Exactly. I think people often confuse pressure, volume, and flow rate. The high-pressure side of a regulator has a very small volume. It takes very little gas volume to fill it to pressure, so even if the valve was restricting the flow rate it would still fully pressurize the regulator. It might just take a bit more time than normal to do so. But, as you observed, even when the flow rate is insufficient to provide the necessary volume of gas for breathing it still pressurized the HP side of the regulator and provided a pressure reading on the SPG. The only way to provide enough gas for breathing and yet not register on the SPG would be a condition of HIGH FLOW and LOW PRESSURE.

-Ben (walking away...)

[Fishstiq]

3 spg's, at least 2 1st stages, one tank, one valve. Tank and valve are the only common denominators to the problem, so one of them is the source of your grief.

Theory #1 - during hydro, some moisture or dust or tumbler rock sand thingies got left in the tank. They work their way into the dip tube or valve and gum up the works. I'll leave the physics of flow, pressure, volume, time, mass, space time continuims, boyles law, odds, variables, 1040EZs, jelly bean velocity, black versus yellow, and collapsable snorkels to the people who can do science.

Theory #2 - I don't know if anyone thought of this yet, but could the tank be empty?