Class A liquid to be purged from tank and piping before use with Class B liquid

liquid. No compartment of a tank vehicle which has contained a Class A liquid on the prior loading shall be loaded with Class B liquid until such compartment and all piping and accessory delivery equipment connected thereto have been drained of all Class A liquid and then flushed with a quantity of Class B liquid sufficient to clear them of any remaining Class A liquid; or cleared of Class A liquid by some equally effective method.