Help identify this surplus electrical equipment

[treeman250r]

i buy surplus electrical equipment from main power company in ny 3 of these tanks were in lot 27" tall 18" diameter pressure gage goes from 0/30 psi up and 0/30 in HG vac down marked negative on bottom positive on top also has tire air valve no part numbers anybody have idea what it is?has 3 holes on each end 406405

[SecondGen]

i buy surplus electrical equipment from main power company in ny 3 of these tanks were in lot 27" tall 18" diameter pressure gage goes from 0/30 psi up and 0/30 in HG vac down marked negative on bottom positive on top also has tire air valve no part numbers anybody have idea what it is?

Can you post more pics, looks like there might be some copper attached to them?