stick pressure gauge?

[Bob DBF]

Was there a glass tube in the back of the gauge?

As far as the pin gauge in the valves, no glass.

They are my favorite for the Spare Air but at best they say "Really full", "Partially full" or "Not full at all".

At 3 cuft, all three are about the same.

 

[Akimbo]

I am considering using it for a blind diver.

I saw those in Europe in the 1970s. The word was they weren't very reliable. Another option to consider is to use a technique developed by British Navy divers for use in zero visibility called Progressive Equalization. I use it but it requires doubles. I have made up sets of double 45s, 50s, and 90s in a valve-down configuration but can be used with valve-up rigs.

 

[PBcatfish]

One of my USD regulators from the 1960's has a pin gauge on it. It's from back in the days when 2250 was the max fill pressure, so I don't even like to use it with a 3,000 psi aluminum tank.

As was said, a plastic version of that pin gauge is now standard issue on spare air units. They also offer a small dial gauge as an upgrade.

I had not seen a pin gauge on the end of a hose like that before. It would be easy enough for any machine shop with a lathe to produce, providing that someone knew how to properly specify o-ring gland dimensions & calculate the K equation for a spring.