Current through September 16, 2024
Except as otherwise authorized by the Division or the
appropriate district board of health, if a double check valve assembly is
installed on a service connection:
1.
The double check valve assembly must be installed:
(a) In a horizontal and level position,
except that the double check valve assembly may be installed in a vertical
position if the assembly has been:
(1)
Specifically designed for operation in that position; and
(2) Tested and certified to be suitable for
operation in that position by an approved backflow testing
laboratory.
(b) As
closely as practicable to the service connection, on the opposite side of the
service connection from the public water system.
(c) Above ground and, to the extent possible,
not less than 12 inches nor more than 36 inches above the finished grade, as
measured from the bottom of the assembly.
(d) In such a manner as to be readily
accessible for maintenance and testing.
2. There must be no type of outlet, tee, tap,
take-off or connection to or from the service line between the service
connection and the double check valve assembly.
3. Expansion tanks or pressure relief valves
must be provided as appropriate for the potential threat of water hammer and
thermal expansion.
4. The double
check valve assembly may, if above-grade installation is impracticable and the
Division or the appropriate district board of health approves of the
installation, be installed in a below-grade vault in such a manner that:
(a) The top of the double check valve
assembly is not more than 8 inches below grade.
(b) There is:
(1) At least 12 inches of clearance between
the bottom of the vault and the bottom of the double check valve
assembly;
(2) At least 24 inches of
clearance between the side of the vault and the side of the double check valve
assembly with test cocks; and
(3)
At least 12 inches of clearance between the side of the vault and the other
sides of the double check valve assembly.
(c) To the extent warranted by climatic
conditions, the double check valve assembly is protected from
freezing.
(d) The vault has
adequate drainage to prevent the accumulation of water, which drains to
daylight, to free-draining soil or to a sufficient amount of gravel placed
under the vault to provide for free drainage and prevent the accumulation of
water under the vault. A vault that does not have an integrated bottom must be
placed on a layer of gravel which is not less than 3 inches deep.
(e) The vault is protected from
vandalism.
(f) The vault is not
located in an area subject to vehicular traffic.
5. The double check valve assembly may be
installed indoors if:
(a) The installation
complies with subsections 1 to 4, inclusive; and
(b) The double check valve assembly has a
clearance of:
(1) At least 12 inches on
top;
(2) At least 24 inches on the
side with test cocks; and
(3) At
least 12 inches on the other sides.
Added to NAC by Bd. of
Health, eff. 2-20-97; A by Environmental Comm'n by R194-08,
10-27-2009
NRS
445A.860
