Is it legal to use a ball valve as a dump valve?

Think about all the Weatherhead and Bendix-Westinghouse brass fittings on the older trucks. None i’ve ever seen have a Dot approval code stamped or molded on them. Used to be the Gates C5E and Aero-quip stratoflex hose had a green stripe painted on them to denote Dot approved for air brake use. It was an easy id for inspection. Within the last year or two they no longer put that green stripe on the new hoses being made. Gates says it is no longer necessary for Dot and is an added expense for them.

 

When I pulled tanks. It was two valves and a cap.