Hi Guys.
Back in the dim and distant past when just a sprog, I was taught that when preparing to use Oxy/Acetylene cylinders.
You open both using the bottle key, so that either can be shut off in 1 quick movement. You should not have to reinsert the bottle key to close off the valve.
Also that it was necessary to leave the bottle key in the Acetylene Cylinder. Because this was the catalyst and Oxygen will not burn on it's own.

With this in mind I asked our apprentice to set up the porta-pack prior to doing some brazing. Asking how he had been taught to set them up?

"Open both valves 1/2 a turn and leave the key in the Oxygen!"

Apparently He and his contemporaries have been told you leave the key in the Oxygen as that is the cylinder that would explode! (Due to the Higher pressures I assume?)

What does anyone think?

Grizzly