Bell & Gossett Airtrol® Tank Fitting, Air Control, Series: ATF, 1/2 x 3/4 in Nominal Size, MNPT x FNPT, 175 psig, 250 deg F, Cast Iron, 20 to 22 in Dia
Copper and copper plated tubes Brass vent tube fitting 20 to 22 in dia compression tank Model ATF-20