Bob DBF
Contributor
The black square is there to tell you it may be empty, it was.
Guess the PSI
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The black square is there to tell you it may be empty, it was.
No its not.
600 is the start of the orange lines.
The black square is empty/0-200psi/mechanical gauges aren't accurate here zone.
Bob DBF
Contributor
600 psi is clearly marked, well above the black square. Without taking calipers to the picture, I'd guess the top of the black square is 300 psi, or less.
Yes, time to pull the J rod (push "down" the J valve) and begin your ascent.
rx7diver
Let SPG go to (near) zero. Then pull the rod. SPG will then show approx 250-500 psig, depending.
ETA: At least, I think this is what happens with all J valves. About to test my newest J valve (which I received earlier this week from The Scuba Museum), a knob-on-the-top U.S. Divers model that is older than my other two J valves.
rx7diver
Duh! Brain fade! I suppose this is obvious--since the SPG "sees" the pressure that the 1st stage "sees."
At any rate, I just unpacked my "new" J-valve, mounted it on a spare cylinder, and tested it to confirm it. This one shows ~250 psig when the J-valve is pulled.
P.S.: And I was reminded that a Poseidon Odin absolutely will drain the remaining air from your cylinder if you let the pressure get too low!
rx7diver
Phteven
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Waterwulf
Contributor
Yup, that's how a J Valve is supposed to work. I like J valves on my tanks. I never plan on clicking it to Reserve but it's nice to have. It's wonderful to hear that hiss of pressure flooding into your system when you pull the rod. We trained pretty extensively on them back in the early 70's. SPG's were not around so we had to depend on the J Valve. We trained so hard to check that the metal rod was UP, that we all walked around for six months waving our left hands behind our butts like we were waving away stinkers. I still remember the Instructors: "You WILL check that valve at least every ten minutes. If you don't check it, you will FAIL the exercise. You will NOT get extra credit for checking it more often but it MIGHT save your life".
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