Proper J-Valve Function
- I try to run out of air with my J-Valves at least once a year to make sure they are functioning properly. 3 weekends ago, I dove one set of Twin 38s that I had been servicing and thought I had a properly working J-Valve on but instead, the reserve leaked past the J-Valve and I breathed the tanks right down to zero. When I got home, I tested it by letting the air out with the J-Valve on and it just leaked everything out past the valve.
- So LAST weekend I tried diving with two other Twin 38s that I knew had properly functioning J-Valves. The first one worked perfectly: I breathed it down to a hard draw, pulled the lever, heard the air balance between the two tanks, and I breathed easy for at least 5 minutes more.
- But the second set just kept giving me air until I gave up waiting for the reserve and ended the dive. When I pulled the lever up by the car, I could hear the tanks balancing but only briefly. And when I checked the pressure, it barely moved to 100 psi. Now, this set I have breathed down to a hard suck and actuated the reserve successful on several occasions. So I filled it up past 500, flipped the reserve up and opened the valve to empty the tanks. It emptied down to a slow leak but it never totally stopped. And once again when I pulled the lever, the tank balancing sound was very short and the measured pressure was barely 100 psi.
- Now, I've had twin tanks that I thought were empty until I pulled the reserve lever... The reserve was sealed that perfectly. But I've also been told that they're supposed to leak a little since they're only held closed by a spring... Which your breathing can overcome somewhat.
- I would prefer these things to seal the reserve air with no leaks until I need it. My question is whether this is proper and possible and second where can I get new seats and springs?
P.S. I looked in my Basic Scuba book and there is a difference in the reserve mechanism of the old 1/2 NPT threaded manifolds and the new 3/4 manifolds. The springs have the same part number but the seat is called a flow check on one and a disk and something on the other... With different part numbers.