Sec. 23-38. Construction and installation requirements for air gaps or other devices.
(a) The discharge pipe of an air gap shall terminate:
(1) A minimum of two (2) pipe diameters of the discharge pipe or six (6) inches, whichever is the lesser, above the maximum recorded flood level or above the flood level rim of the receiving vessel, whichever is higher; or
(2) A minimum of three (3) pipe diameters of the discharge pipe or six (6) inches, whichever is the lesser, above the maximum recorded flood level or above the flood level rim of the receiving vessel, whichever is higher where:
a. A side wall, rib, or similar obstruction is spaced closer than three (3) diameters from the piping affecting the air gap; or
b. Two (2) intersecting walls are located closer than four (4) pipe diameters from the piping affecting the air gap.
(b) Only those models of double check valve assemblies, reduced pressure principle backflow preventers, and pressure vacuum breakers acceptable under the Indiana Plumbing Code pursuant to the fire prevention and building safety commission rules at 675 IAC 16-1.3 shall be installed.
(c) Reduced pressure principle backflow preventers shall be installed horizontally with:
(1) No plug or additional piping affixed to the pressure differential relief valve port; and
(2) The pressure differential relief valve port a minimum of twelve (12) inches above floor level.
Additionally, the device must be installed at a location where any leakage from the pressure differential relief valve port will be noticed, and that allows access to the valve for maintenance and testing from floor level, without use of a ladder or other similar temporary apparatus, and that will not subject the device to flooding, excessive heat, or freezing.
(d) All double check valve assemblies shall be installed at a location that allows access to the device for maintenance and testing from floor level, without use of a ladder or other similar temporary apparatus, and that will not subject the device to flooding, excessive heat, or freezing.
(e) Pressure vacuum breakers shall be installed as near as possible to the irrigation facility, at a location that allows access to the device for maintenance and testing from floor or ground level, without use of a ladder or other similar temporary apparatus, and that will not subject the device to flooding, excessive heat, or freezing. Additionally, the device must be installed between two (2) tightly closing shut-off valves, with its center line or datum point a minimum of twelve (12) inches above:
(1) Floor level;
(2) The highest downstream piping or shutoff valve; and
(3) The highest downstream overflow rim or discharge point.