(a) Air gap separations provide maximum protection from backflow hazards and may be utilized at premises where a substance is handled that would be hazardous to health if introduced into the potable water system.
(b) An air gap separation shall be at least twice the diameter of the supply pipeline measured vertically above the top rim of the receiving vessel, in no case less than one inch. If splashing is a problem, tubular screens may be attached or the supply line may be cut at a 45 degree angle. The air gap distance is measured from the bottom of the angle. Hoses shall not be allowed.
(c) Air gap separations shall not be altered in any way without prior approval from the director, and shall be available for inspection at all reasonable times.
(d) Side walls, ribs or similar obstructions do not affect air gaps when spaced from the inside edge of the spout opening a distance greater than three times the diameter of the effective opening for a single or a distance greater than four times the effective opening for two intersecting walls.
(e) In cases where there are three or more side walls, ribs or similar obstructions extending from the water surface to or above the horizontal plane of the spout opening other than as specified in subsection (d) above, the air gap shall be measured from the top of the wall.
(f) The effective opening shall be the minimum cross-sectional area at the seat of the control valve or the supply pipe or tubing which feeds the assembly or outlet. If two or more lines supply one outlet, the effective opening shall be the sum of the cross-sectional areas of the individual supply lines or the area of the single outlet, whichever is smaller.
Air Gap Separation
Notes:
(1) Provides maximum protection.
(2) The vertical, physical separations must be at least twice the diameter of the inlet pipe but never less than one inch.
(Ord. 12274, § 1, passed 11-28-1995)