Scuba Cylinder Valve Malfunction

I recently found a fully charged scuba cylinder on my boat that was full of air, but the valve handle will not turn. I exerted as much force as I dare, but the valve will not open. What should I do? I did some research online and found very little guidance.

Has this ever happened to you?

After some thought, I have decided that my currently known options for depressurization of the cylinder are as follows:

Apply “excess” torque to the valve handle in an effort to open the valve, despite the possibility of breaking the valve stem.
Slowly unscrew the over pressurization disc retainer until air begins to escape.
Suspend the cylinder upside down and immerse the valve in an ultrasonic cleaner in an effort to free the valve stem.
Transport the cylinder to a hydrostatic testing facility and let them solve the problem.

Action Plan: I consider both option 1 and 2 to be slightly risky. So, I plan to try option 3 (as I have access to an ultrasonic cleaner, and the attempt will not damage the components or put me at risk). If this is not successful, then option 4 is next in line (I will telephone hydrostatic test facilities in an effort to find a professional who is willing to solve this problem).

Stay Safe!

Dave Wills