early 450 Air Pressure Valve How to Test?

[chiwanga]

I have a few used air pressure valves in a box and I would like to know how to test them. part number 0280100100

They obviously have some kind of a diaphram inside, and it holds vacuum that I create at the air nozzle. there is also a 4 prong electical connector giong to it, and some kind of an adjuster on the end that looks to have been sealed on from the factory.