Yes, in the 'gas world' the color of the cylinder denotes at a glance what gas is in it. But that color systems is not exactly universal around the world. :-(
Be that as it may, a navy might also not like various colored cylinders exposed on an otherwise 'grey' ship, and may paint them all 'grey' and denote what is in them by lettering on the side, or some such?
: I am presently painting my 1/200 scale model
: of the USS Missouri and would like to know
: if anyone has the answer for this
: question....What colours are the pressurized
: cylinders seen on deck? In some models I've
: see them as green, others as a yellow-brown.
: Which is it, or are the in different colors
: depending on the contents?