§ 6-20-070. Selection, approval and installation of devices.

A.

Selection. Vacuum breakers and backflow preventers shall be selected on the degree of hazard and the type cross connection. The degrees of hazard are determined by whether the impurities involved are contaminants or pollutants; the type cross connection by whether it is non-pressure or pressure (see definitions section).

1.

Cross Connections, Non-pressure Type. This type connection, when not protected by a minimum air gap, shall be protected by an appropriate vacuum breaker or an appropriate backflow preventer.

2.

Cross Connection, Pressure Type. This type connection shall be protected by an appropriate backflow preventer only.

Caution: Neither atmospheric nor pressure type vacuum breakers shall be used on pressure type cross connections.

3.

[Lawn Sprinkler System.] Note: Because a lawn sprinkler system serves an environment that is open to atmosphere, it is not classified as a pressure type cross connection. Due to the special nature of the installation, however, it is recommended that if no chemicals are injected into the system, minimum protection against backflow shall include a double check valve assembly. If chemicals could be injected easily, minimum protection shall include a reduced pressure zone type back flow preventer.

4.

Accepted Materials. Vacuum breakers shall be bronze. Backflow preventers, including accessories, components, and fittings in size 2-inch and smaller shall be bronze with threaded connections. Size 2½-inches and larger may be iron or bronze bodies, with flanged connections.

B.

Approval of Devices. All vacuum breakers and backflow preventers must be approved by the BLW in accordance with the applicable standards of the American Society of Sanitary Engineering, the American National Standards Institute, the American Water Works Association, or the University of Southern California.

C.

Installation of Devices. Vacuum breakers and backflow preventers equipped with atmospheric vents, or with relief openings, shall be so installed by the customer and so located as to prevent any vent or any relief opening from being submerged. They shall be installed in the position as recommended by the manufacturer, and shall be protected from freezing.

1.

Vacuum Breaker, Atmospheric Type (VB-AT). This device shall be installed at least six inches above the highest outlet or the overflow level on the nonpotable system. It shall be installed downstream of the last shut-off valve.

2.

Vacuum Breaker, Pressure Type (VB-PT). This device shall be installed at least twelve (12) inches above the highest outlet or the overflow level on the nonpotable system. It may be installed upstream of the last shut-off valve.

3.

Vacuum Breaker, Hose Type (VB-HT). This device shall be installed directly on the hose threads, if not an integral part of the valve. It may not be subjected to continuous pressure, static or flowing. Nor shall it be attached to a freezeless type hydrant unless it is a model specifically designed for this service.

4.

Backflow Preventer, Dual Check (BFP-DuC). This device shall not be buried in earth but may be installed below ground in such as a meter box. A positive shut-off valve shall be near the inlet side of the device; when below ground, near both sides.

5.

Backflow Preventer, Double Check Valve (BFP-DCV). This device shall not be buried in earth but may be installed below ground in a pit provided ball valve test cocks fitted with brass plugs are used. A positive shut-off valve shall be near the inlet and outlet sides of the device, and three ball valve test cocks provided on the device. A fourth test cock shall be provided on the upstream side of the inlet shut-off valve. When below ground, a union or flange shall be near the inlet and outlet sides. No intervening connection(s) shall be between the shutoff valves and the backflow preventer.

6.

Backflow Preventer with Intermediate Atmospheric Vent (BFP-IAV). This device shall not be installed below ground. Where relief valve discharge could cause water damage, it shall be piped via an air gap, or a funnel, at the vent/relief port to a floor drain or other approved location. A positive shutoff valve and union shall be near the inlet and outlet sides of the device. A bronze strainer with 20-mesh stainless steel screen shall be included between the inlet shut-off valve and the device.

7.

Backflow Preventer Reduced Pressure Zone (BFP-RPZ).

a.

This device shall not be installed below ground. Where relief valve discharge could cause water damage, it shall be piped via an air gap, or a funnel, at the vent/relief port to a floor drain or other approved location. A positive shut-off valve shall be near the inlet and outlet sides of the device, and three approved test cocks provided on the device. A fourth test cock shall be provided on the upstream side of the inlet shut-off valve. A bronze strainer with 20-mesh stainless steel screen shall be included between the inlet shut-off valve and the device on sizes through 2-inch. No intervening branch connection(s) shall be between the shut-offs and the backflow preventer. When the reduced pressure zone device is installed in a line subject to periodic no-flow conditions, and supply pressure subject to fluctuations, an auxiliary directional check with soft disc, capable of functioning in any position the BFP might be installed in, shall be provided between the inlet shut-off valve and the BFP head to lock the supply pressure in, and prevent unnecessary discharge through the vent/relief port. Make-up lines to chilled water systems are examples of installations where a drop in supply pressure might occur during no-flow conditions.

b.

When a water pressure reducing valve is required in the same line with the RPZ device, it is usually possible to locate the reducing valve upstream of the device and take advantage of the check valve effect of the reducing valve. In such case, the auxiliary directional check would not be required.

(Code 1978, § 5-5007; Ord. No. 5575, 6/12/96)