XS Scuba manifolds with engravings vs HOG manifolds without.

[Scared Silly]

It's not magic, it's science. The valve is not considered suitable for oxygen service unless it can pass the oxygen gas section of tests exactly as described in the CGA V9 standard for valves. That 7 thread DIN valve is described in the DIN standard as being suitable for cylinders with test pressures up to 450 bar. Take 120% of the maximum pressure that the valve might see and then pressurize the valve (as fast as possible) with ultra pure five nines oxygen that has been pre-heated to adiabatic combustion temperature. Thus subjected to the conditions of the test, if the valve catches on fire, the valve fails the test and the valve is not considered suitable for use with oxygen. The Thermo brand Nitrox 5-thread PRO DIN/K valve will pass, and the 7-thread DIN valve will not.

I should have put a few by my post. My point is that valve rating is based its purpose not the valve strength.

Oh, and it is not science, it is engineering.