As used in this Part 1, the following terms
shall have the meanings indicated:
AIR-GAP SEPARATION
A physical break between a supply pipe and a receiving vessel.
The air gap shall be at least double the diameter of the supply pipe,
measured vertically above the top rim of the vessel, in no case less
than one inch.
APPROVED CHECK VALVE
A check valve that seats readily and completely. It must
be carefully machined to have free moving parts and assured watertightness.
The face of the closure element and valve seat must be bronze, composition
or other noncorrodible material which will seat tightly under all
prevailing conditions of field use. Pins and bushings shall be of
bronze or other noncorrodible, nonsticking material, machined for
easy, dependable operation. The closure element, e.g., clapper, shall
be internally weighted or otherwise internally equipped to promote
rapid and positive closure in all sizes where this feature is obtainable.
APPROVED DOUBLE-CHECK-VALVE ASSEMBLY
An assembly of at least two independently acting check valves,
including tightly closing shutoff valves on each side of the check
valve assembly and suitable leak-detector drains plus connections
available for testing the watertightness of each check valve. This
device must be approved as a complete assembly.
APPROVED REDUCED-PRESSURE-PRINCIPLE BACKFLOW PREVENTION DEVICE
A device incorporating two or more check valves and an automatically
operating differential relief valve located between the two checks,
two shutoff valves, and equipped with necessary appurtenances for
testing. The device shall operate to maintain the pressure in the
zone between the two check valves, less than the pressure on the public
water supply side of the device. At cessation of normal flow, the
pressure between check valves shall be less than the supply pressure.
In case of leakage of either check valve, the differential relief
valve shall operate to maintain this reduced pressure by discharging
to the atmosphere. When the inlet pressure is two pounds per square
inch or less, the relief valve shall open to the atmosphere, thereby
providing an air gap in the device. To be approved, these devices
must be readily accessible for maintenance and testing and installed
in a location where no part of the valve will be submerged. The enclosure
must be self-draining, so that the large amount of water which the
relief valve may vent will be disposed of reliably without submergence
of the relief valve. This device must also be approved as a complete
assembly.
BAROMETRIC LOOP
A loop of pipe rising approximately 35 feet, at its topmost
point, above the highest fixture it supplies.
CERTIFIED BACKFLOW PREVENTION DEVICE TESTER
A person who is examined annually by the water district and
found competent for the testing of backflow prevention devices. He
shall be provided with an appropriate identification card, which must
be renewed annually. Failure to perform his duties competently and
conscientiously will result in prompt withdrawal of his certification.
CROSS-CONNECTION
Any unprotected connection between any part of a water system
used or intended to supply water for drinking purposes and any source
or system containing water or substance that is not or cannot be approved
as equally safe, wholesome and potable for human consumption.