All automatic fire suppression systems shall be protected from backflow with an approved double check valve assembly. Any fire suppression system into which chemicals of any type (corrosive, antifreeze, etc.) can be added shall be protected at the service connection with an approved reduced pressure principle assembly. In lieu of such protection, an antifreeze loop may be individually protected with an approved reduced pressure principle assembly, in addition to proper service line protection. (Ord. 17835 § 88, 5-14-02. Code 1981 § 10-317. Code 1995 § 26-464.)