--- In STMFC@..., Anthony Thompson <thompson@...> wrote:

I sure hope the caps have different threads so they can't be
matched to the wrong bottle. Otherwise it strikes me as a pretty
dangerous arrangement.

With the suppliers I've seen (like Matheson)it's not the caps that have
unique threads, it's the cylinders themselves and the pressure reducer
assemblies.

The aforementioned assemblies have the right materials of
construction,seals etc. for specific gases besides having the gage.

A reducer for one gas will not fit on a bottle of another - the threads
are different.

If you have a set up for oxygen you can't replace the tank with
anything but another tank of oxygen. It's pretty frustrating when you
work in a lab that has 10 unused reducers and none fit on a new bottle
of gas.

Ed Mines