North Dakota Administrative Code › Title 7 - Agriculture Commissioner › Article 7-10 - Chemigation Regulations › Chapter 7-10-02 - Equipment Requirements › Section 7-10-02-02 - Allowable antisiphon devices

Current through Supplement No. 393, July, 2024
One of the following antisiphon devices must be installed as
				  required in this section before chemigation in an irrigation system may take
				  place.
1.
Check valve with
				vacuum relief and low pressure drain.
A corrosion-resistant check valve
				must be located between the water supply pump discharge outlet at the point of
				chemical injection. Location on the suction side of the water pump is not
				allowed. The check valve must be either spring loaded with a chemically
				resistant sealing surface or otherwise capable of preventing leakage. The
				direction of flow must be clearly indicated on the outside of the device. The
				vacuum relief valve must be installed on top of the irrigation pipe on the
				inlet side of the check valve. The vacuum relief valve must be a minimum of
				three-fourths inch [19.05 millimeters] in diameter. The low pressure drain must
				be located on the inlet side of the check valve at the lowest point. The drain
				must be mounted in the pipe in such a way that any check valve leakage enters
				the drain rather than flowing on toward the water supply. The drain must be at
				least three-fourths inch [19.05 millimeters] in diameter with a closing
				pressure of at least one pound per square inch [7 kilopascals] and not
				exceeding five pounds per square inch [35 kilopascals]. If the drain is within
				twenty feet [6.10 meters] of the water source, the system must provide a means
				to carry the drainage away or the surface must be graded to assure drainage
				away from the water source. Manual valves may not be located on the outlet side
				of the drain.
2.
Reduced
				pressure principle device.
The reduced pressure principle device must
				consist of two independently acting check valves, together with a pressure
				differential relief valve that is located between the two check valves. This
				device must be located between the pump discharge outlet and the point of
				chemical injection. The differential relief valve must have a minimum clearance
				of twelve inches [30.50 centimeters] above the ground level or grade.
3.
Double check valve.
The double
				check valve assembly must be composed of two single, independently acting check
				valves. The double check valve must be located between the pump discharge
				outlet and the point of chemical injection.
4.
Airgap.
An airgap must be a
				physical separation between the free flowing discharge end of a water pipeline
				and an open or nonpressurized receiving vessel. To have an acceptable airgap,
				the end of the discharge pipe must be located a distance of at least twice the
				diameter of the pipe above the topmost rim of the receiving vessel. In no case
				can this distance be less than one inch [2.54 centimeters]. The airgap must be
				located between the pump discharge outlet and the point of chemical
				injection.
5.
Other
				acceptable devices.
Other equipment utilizing new technology or other
				backflow prevention devices as specifically approved in writing by the
				commissioner of agriculture may be used.
General Authority: NDCC
					 4-35.1-03
Law Implemented: NDCC
					 4-35.1-02,
					 4-35.1-03