scope:

Description

This standard covers design and performance requirements for freeze resistant sanitary yard hydrants to prevent backflow due to backsiphonage and backpressure. These units shall be classified as follows:

a) Type 1 devices shall consist of two independent checks, force loaded or biased to a closed position, with an atmospheric vent located between the two check valves, which is force loaded or biased to an open position, and a means for attaching a hose. When the hose is attached, the Type 1 device shall be freeze resistant.

b) Type 2 devices shall consist of two independent checks, force loaded or biased to a closed position, with an atmospheric vent located between the two check valves, which is force loaded or biased to an open position, and a means for attaching a hose. When the hose is removed, the Type 2 device shall be freeze resistant.

c) Type 3 devices shall consist of one check valve, force loaded or biased to a closed position, with an atmospheric vent, which is force loaded or biased to an open position, and means for attaching a hose. When the hose is attached, the Type 3 device shall be freeze resistant.

d) Type 4 devices shall consist of one check valve, force loaded or biased to a closed position, with an atmospheric vent, which is force loaded or biased to an open position, and a means for attaching a hose. When the hose is removed, the Type 4 device shall be freeze resistant.

e) Type 5 devices shall consist of a removable mechanical backflow protection device with at least one check valve, force loaded or biased to a closed position, and an atmospheric vent, which is force loaded or biased to an open position, and a means for attaching a hose. When the hose and backflow protection is removed, the Type 5 device shall be freeze resistant and shall not allow a hose to be attached.

Pressure

Operating Pressure Range

The devices shall be designed for a minimum working pressure range of 20.0 psi to 100.0 psi (137.9 kPa to 689.5 kPa) or the manufacturer's maximum rated pressure, whichever is greater.

Temperature Range

The devices shall be designed for flow temperatures of 40.0 °F to 140.0 °F (4.4 °C to 60.0 °C) or the manufacturer's maximum rated temperature, whichever is greater.

Connections

Outlet Thread

Garden hose connection threads shall be 3/4 NH or 1 NH garden hose couplings in compliance with ASME B1.20.7.

Inlet Threads

Pipe threads shall comply with ASME B1.20.1.

Water Flow Capacity and Pressure Loss

Devices shall meet the flow rates and pressure losses that are referenced in Table 1.

Installation and Service

Devices shall be designed and built such that, after installation, repair or replacement of the elastomeric parts shall be accomplished without the need to excavate the soil surrounding the hydrant.