§ 33-274. Reduced pressure principle backflow prevention assembly (RP).

All RP assemblies shall be tested in each of the following circumstances: immediately upon installation, after repair, if it is moved, at least annually and more often if deemed necessary.

(1)

RPs shall be utilized at premises where a substance is handled that would be hazardous to the public health if introduced into the potable water system. An RP is normally used in locations where an air gap is impractical. An RP is effective against both backsiphonage and backpressure.

(2)

RPs shall be sized to provide an adequate supply of water and pressure for the premises being served.

(3)

Premises where non-interruption of water supply is critical shall be provided with two (2) assemblies of the same type installed in parallel. They shall be sized in such a manner that either assembly will provide the minimum water requirements while the two together will provide the maximum flow required.

(4)

Bypass lines are prohibited. Pipe fittings which could be used for connecting a bypass line shall not be installed.

(5)

The assembly shall be readily accessible for testing and maintenance and shall be located in an area where water damage to buildings or furnishings will not occur from relief valve discharge. An approved air gap funnel assembly may be used to direct minor discharges away from the assembly; this assembly will not control flow in a continuous relief situation. Full relief valve discharge flow should be considered when installing this assembly.

(6)

Enclosures shall be designed for ready access and sized to allow for the minimum clearances established in the Standard Operating Procedure Manual.

(7)

All RP assemblies shall be tested in accordance with this article.

(8)

Variances from these specifications will be evaluated on a case-by-case basis. Any deviations shall be prohibited without prior written approval of the city manager.

(9)

RP assemblies may be installed in a vault only if relief valve discharge can be drained to daylight through a boresight type drain. The drain shall be of adequate capacity to carry the full rated flow of the assembly and shall be screened on both ends.

(10)

An approved air gap shall be located at the relief valve orifice of RP assemblies. This air gap shall be at least twice the diameter of the incoming supply line as measured vertically above the top rim of the drain and in no case less than one inch.

(Ord. No. 2047, § 7, 8-21-00)