Apollo-era Aerozine 50 (N2H4/UDMH) fill valve assembly, measuring approximately 12.25" long and 2" in diameter, marked on the cover, "Coupling-Class 2, Type I, N2H4/UDMH Fill Vent Disconnect, NAA/S & ID Cont No. ME273-0024-0002." The attached filter tube assembly is marked on the side: "Filter Assy., 15 Micron Absolute…S/N 410, P/N 15241-606, Date of Mfg. 9-1-71." Additional metal tags are attached at center. This fill valve assembly is designed to make a safe connection between the source of the fuel and the tank to be filled: the valve cannot be opened until the connecting end is fully seated against the receiving receptacle.
Aerozine 50 is a rocket fuel made with a 50:50 mix by weight of hydrazine (N2H4) and unsymmetrical dimethylhydrazine (UDMH). It was used by both the Apollo Lunar Module and by the Apollo CSM (in the Service Propulsion System engine).
