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Hoffman air vents for radiators

Our condo building has a one-pipe steam system that operates at low pressure. My question concerns the Hoffman air vents that go on the radiators. We have a number of the 1A, 40, and 70A vents. What I want to know is if these are all more or less interchangeable. We generally use the 40's. The 1A's are adjustable and allow faster or slower venting. Does anyone know what the 70's are for? They are all the same size.

Comments

  • Big Ed
    Big Ed Member Posts: 1,117
    #70A

    Hoffman #70A could run at higher operating pressures over the #40. 11# rather then 6# . Was made to meet Federal specification WW-V-151 just in case it come up in Trivel Pursuit :) Its a heavy duty #40...
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