Just another 2 cents to add, if somebody hasn’t already pointed it
Concerning the oxygen tank/regulator, you never want to open the tank
when the T wrench is turned in any amount at all, as the pressure in
a full tank, at 1500 psi, will slam into that diaphragm and spring a
leak in it, which means a new regulator since nobody wants to fix
those (liability issues). Also, when you open the tank, turn the
valve all the way out and snug it a bit in the fully open position.
Oxygen tank valves are double seating valves. Due to the extremely
high pressure, they need to seat in the open position to prevent
leaking around the valve stem.
David L. Huffman