All presently installed backflow prevention assemblies which do not meet the requirements of Section 10A.40.030 but were approved devices for the purposes described therein at the time of installation and which have been properly maintained, shall, except for the inspection and maintenance requirements under Section 10A.40.060, be excluded from the requirements of this Chapter so long as the director is assured that they will satisfactorily protect the city's water system. Whenever the existing backflow prevention assembly is moved from its present location or requires more than minimum maintenance or when the director finds that the maintenance constitutes a hazard to health, the unit shall be replaced by an approved backflow prevention assembly meeting the requirements of Section 10A.40.030. (Ord. 92-18 §4, 1992).