Bung Size: 2″ NPT Application: Corrosives & General Solvents Material: Stainless steel FM approved vent for use with drums in the hori­zontal (pouring) position. Automatically relieves pressure at 5 PSI. Flame arrestor protects contents. Manual vacuum relief by lifting and rotating valve stem. Maxi­mum flow of 220 CFM at 20 PSI. Fits 2″ NPS bung in steel and plastic drums. Use for corrosives and general solvents.