johndiver999
Contributor
So I have been diving with an old scuba pro spg (a heavy brass one with a glass face) for several years. I got it used and it is old, but it always seemed to work perfectly with the slight exception of, showing zero or near zero pressure when there is still enough gas to get some air for a couple of minutes. Maybe the gauge was showing zero when the real pressure was like 75 psi?
It has been like this for years and I never cross checked with another gauge, "because who cares, if it shows a tiny bit of conservativeness at the very bottom of the tank"? In the last year or so, I have started the practice of breathing down my nitrox on the boat between dives - in an attempt to accelerate offgassing, which gives me a pretty frequent opportunity to see how the gauge works as the tank is drained to zero.
So two days ago I was on my stop with about 2 minutes completed and about 4 to go (at 15-20 feet). I had not checked my gas carefully when I left the bottom, but I kinda knew I had enough for the ascent and the stop. Probably like 5-600 or something. I'm diving solo in 110 with a small pony bottle, so this is more than enough gas to get me to the surface. I don't need any kind of reserve for a buddy, because he is driving the boat.
Anyway, while 2 minutes into my stop, I take a breath and I think I feel a little resistance at the end of a gentle inhalation (like the tank is close to empty). So what do I do? Instinctively I take a really hard and fast inhalation to test if there actually was a restriction in gas delivery or perhaps it was my imagination? I also simultaneously flip the console over and look at the pressure - two independent checks on the pressure. At first glance, the needle reads 350 (so I am confused) , and then, as I suck hard, it instantly falls to ZERO and the inhalation was quite restricted.
Obviously the needle had been stuck at 350 psi and a really quick inhalation caused it to drop. It was kinda funny to actually witness the needle become unstuck, but only because I had a pony bottle which contained 2-3 times the required volume to complete the stop. Seeing something like that at 60 feet and without a pony would NOT be so amusing!
I don't recall having this kind of failure before. I threw it in the garbage (although it looked perfectly fine) and replaced with another one from my used gear stash.
Obviously not a big deal, but perhaps a good reminder to not depend too much on any one piece of gear.
It has been like this for years and I never cross checked with another gauge, "because who cares, if it shows a tiny bit of conservativeness at the very bottom of the tank"? In the last year or so, I have started the practice of breathing down my nitrox on the boat between dives - in an attempt to accelerate offgassing, which gives me a pretty frequent opportunity to see how the gauge works as the tank is drained to zero.
So two days ago I was on my stop with about 2 minutes completed and about 4 to go (at 15-20 feet). I had not checked my gas carefully when I left the bottom, but I kinda knew I had enough for the ascent and the stop. Probably like 5-600 or something. I'm diving solo in 110 with a small pony bottle, so this is more than enough gas to get me to the surface. I don't need any kind of reserve for a buddy, because he is driving the boat.
Anyway, while 2 minutes into my stop, I take a breath and I think I feel a little resistance at the end of a gentle inhalation (like the tank is close to empty). So what do I do? Instinctively I take a really hard and fast inhalation to test if there actually was a restriction in gas delivery or perhaps it was my imagination? I also simultaneously flip the console over and look at the pressure - two independent checks on the pressure. At first glance, the needle reads 350 (so I am confused) , and then, as I suck hard, it instantly falls to ZERO and the inhalation was quite restricted.
Obviously the needle had been stuck at 350 psi and a really quick inhalation caused it to drop. It was kinda funny to actually witness the needle become unstuck, but only because I had a pony bottle which contained 2-3 times the required volume to complete the stop. Seeing something like that at 60 feet and without a pony would NOT be so amusing!
I don't recall having this kind of failure before. I threw it in the garbage (although it looked perfectly fine) and replaced with another one from my used gear stash.
Obviously not a big deal, but perhaps a good reminder to not depend too much on any one piece of gear.
