Mon Jan 12, 2015 7:19 pm
Those sound like the "42's" that were originally sold by the Survivair division for SCBA use in Fire Departments and industrial applications. Since they had the same neck threads as SCUBA some of these appear to have also found their way into the Aqualung division. They are about the same size as the old 1800 psi 38's, but have more of SCUBA tank bottom... not the rounded/hemispherical shape of the early 38's. The ones labeled Survivair came painted white, but I am not sure what color was originally used on the diving version. Come to think of it, I think I remember some white cylinders showing up in the commercial diving division catalog.
I have a couple of these that make great diving cylinders. A little heavier in the water than 38's (just about right in my opinion), but basically the same size. And they have the easier to service straight threads with oring seal like modern SCUBA.
You will probably like them.
The older I get the better I was.