3a NWWP93272300183 SOW Installation Criteria RPPBP With Link (BSC).doc.pdf

Installation Criteria For Reduced Pressure Principal Backflow Prevention Devices

0BWest Wilson Utility District

General:

All backflow prevention devices will be inspected to verify that the units meet the following requirements and tested to verify that the units meet the following as set forth in the 7th Edition of the “Manual for Cross-Connection Control” published by the Foundation for Cross-Connection Control and Hydraulic Research-University of Southern California (FCCCHR, and 1985) before they will be accepted by the West Wilson Utility District. It is encouraged that a water system representative be asked to visit the site to review details of the proposed installation prior to the work.

Requirements:

1. The devices must never be subject to flooding; therefore must:

Never be located in a pit or other area subject to flooding.

Avoid piped drains for enclosures housing the units. Provision must be made for discharging water

(maximum design discharge) directly through the wall of the enclosure housing the unit at a slightly higher elevation than surrounding ground level or maximum flood level.

The lowest part of the relief valve should be located a minimum of 12 (twelve) inches plus the nominal diameter of the service line above the top of the drain port(s) or Grade in order to prevent any part of the device from becoming submerged.

2. RP units used for the protection of the water distribution system must be models acceptable to the water system and currently listed as approved by the Tennessee Department of Environment and Conservation.

Tennessee Department of Environment and Conservation approval is based on acceptable laboratory testing and a one-year minimum field evaluation.

3. The devices must be installed where the units can be easily tested and repaired.

All devices should be installed in accordance with the manufacturer’s installation criteria.

Devices installed in non-removable enclosures must have at least 2 feet clearance on each side of the device to facilitate testing and repairs.

Devices must not be installed higher than 5 feet above the floor unless prior approval is obtained in writing from the water system and special provisions are provided for servicing and testing.

4. The pipelines must be thoroughly flushed to remove foreign material and debris before installing the devices.

5. Is not already provided, high quality tight closing resilient seat shutoff valves must be installed at each end of the device for testing and servicing purposes. A suitable test cock must be provided on the supply side of the valve on the inlet to the device.

6. Provisions must be made to protect the device(s) from freezing. Insulating materials must not restrict the relief valve discharge or accessibility to test cocks or nameplate of the unit.

7. The relief valve must never be plugged, restricted or solidly piped to a drain, ditch or pump. Rigidly secured air gap funnels may be used to direct discharges away from the unit provided an approved air gap separation is provided at the relief valve discharge and again at the discharge end of the drainpipe. A secondary area drain may be required in most installations.

8. The test cocks, valve stems, or nameplates should not be painted and their accessibility, operation or legibility shall not be hampered nor the relief valve discharge passage be restricted by insulation or other coverings.

9. The device must be adequately supported to prevent the unit from sagging. Special supports are needed for units in the 4-to-10-inch size range.

10. The device(s) must be placed in the upright position in a horizontal run of pipe.

11. Adequate drainage should be provided for the relief valve discharge. Relief valves are designed to handle from

5 to 60 GPM (minimum under a zone pressure of 1.5 psi, see 7th Edition of USC-FCCCHR Standards) (FCCCHR, 1985). See Table 1.

12. For applications where water temperatures exceed 110 degrees, only approved hot water devices are to be used.

13. Prior to completing the installation, verify that temperature pressure relief valves on heating vessels are properly installed and are in good working condition.

1BReduced Pressure Zone-type Backflow Assemblies

A. Consists of:

Two spring loaded, resilient seat check valves in series with a relief zone between A relief valve mechanism that automatically functions to maintain a lower pressure (of at least 2 (two) psi) in the zone than on the supply side of unit Tight-closing valves before and after unit and appropriate test cocks to facilitate testing

B. Application:

Protect against both back pressure and back siphon.

For continuous pressure conditions For high hazard conditions

C. Installation criteria:

Must never be subject to flooding, therefore:

a. Never located in pit or other area subject to flooding

b. Avoid piped drains from enclosures around unit-provisions must be made for discharging water from the enclosure housing unit(s) at ground level.

c. The relief valve should be located a minimum of 12 (twelve) inches plus the nominal diameter of the service line above the top of the drain port(s) or Grade. NOTE: check manufacturer’s recommendations to see if this is adequate for servicing the relief valve.

Installed where unit can easily be tested and serviced

a. Observe manufacturer’s recommended clearances

b. Install no higher than 5 (five) feet above floor level unless special provisions have been provided for servicing and testing

Flush lines thoroughly before installing unit Protect against freezing Provided adequate means for handling discharge from relief valve

D. Limitations:

Must be tested regularly (at least annually) to be relied upon May need frequent repairs (depending upon operating conditions

Fittings Required for Backflow Devices

All reduced pressure backflow devices are required to have a horizontally mounted “Y” strainer installed before the device. The Y- strainer catches debris before it reaches the device. There must be a ball valve installed to flush the “Y” strainer.

Device must have all fittings required for testing with caps to protect the fittings from damage and debris.

Device without these fitting will not pass visual inspection.

All fittings should be installed with Teflon Tape, not plumbers cement to reduce the chance of fouling the check valves on the device. These fittings are required for testing the device and will fail initial inspection if not installed.

If you would like to check to see if the device you would like to use is approved, please follow the link below enter the information for the device and it will show you if the device is approved or not.

USC Foundation Approved Backflow Prevention Assemblies (usclist.com) http://usclist.com/

Horizontally mounted “Y” strainer with ball valve for flushing is required for all Reduced

Pressure Backflow Assemblies.

Brian Causey Cross Connection Inspector Office (615) 758-5682 Cell # (615) 394-1397 brianc@westwilsonutility.com