ABSTRACT
Appurtenances portions of a main structure necessary for it to operate as intended that are not considered part of the main structure (hydrants, valves, tees, elbows, etc.). Air gap a positive means of preventing a cross-connection. An air gap should be twice the diameter of the discharge pipe or a minimum of 1 inch above the rim of the tank. Double check valve assembly (DCVA) a positive means of preventing a cross-connection. An air gap should be twice the diameter of the discharge pipe or a minimum of 1 inch above the rim of the tank.
