Groco PNC Series Check Valve Groco PNC Series Check Valves are made from PN series cast bronze nipples. A check valve is placed inside to prevent back-flow in plumbing systems. The check valve imposes almost zero flow restriction, and requires less than 12 PSI to open. Colored bands indicate flow direction green to red, confirmed by the permanent laminated tag. C83600 cast bronze construction NPT threads Not suitable for use with diesel fuel or gasoline Maximum recommended temperature 176 F Spe