Unfortunately my Grandad passed away a few months ago. I guess I am a bit a chip of the old block as I shared his interest in making things. He left a number of tools including an air compressor which was handed down to me. I cleaned it up and read the data plate which stated date of manufacture Oct 1946!
I checked that it worked (as he had not run it for a while) and then stripped it down, cleaned the paint from vulnerable areas of the tank and pressure tested the tank. I did this by filling it with water and pumping it up to pressure with a grease gun. The max working pressure is 150psi so I pumped it up to 230 psi (~1.5 X) as is typical to pressure equipment directive for this sort of thing. Original test pressure was 300psi but I did not dare go this high.
The legs in the picture are of my son running away when I told him he was too close!
After a bit of paint. notice the Aldi special in the background that it will be replacing