scope:

Description

These devices shall have a permanent means to protect against backflow due to either backsiphonage or backpressure. The backflow protection shall include a minimum of 2 mechanisms: an air inlet for preventing backsiphonage and a check valve for preventing backpressure. These devices are terminal fittings that supply water to hose connections without danger of freezing.

These devices shall be used on systems where the only source of low head backpressure comes from an elevated hose equal to or less than 10 feet (3 meters) in height. The outlet of this device shall not be subjected to more than 12 hours of continuous water pressure.

The devices shall be classified as follows:

(a) Type A: The backflow protection shall include 3 mechanisms for protection: 1) an air inlet for preventing backsiphonage, 2) a check valve for preventing backpressure and 3) a mechanism that relieves backpressure. The hose shall be removed to prevent damage to the device from freezing.

(b) Type B: The backflow protection shall include 3 mechanisms for protection: 1) an air inlet for preventing backsiphonage, 2) a check valve for preventing backpressure and 3) a mechanism that relieves backpressure and a mechanism that drains the water from the hydrant when the hose is attached and the hydrant is manually closed. The hose need not be removed to protect the device against damage from freezing.

(c) Type C: The backflow protection shall include 2 mechanisms for protection; 1) an air inlet for preventing backsiphonage and 2) a check valve for preventing backpressure. The hose shall be removed to protect against damage to the device from freezing.

Sizes

The device size is specified by the inlet connection and the length of the device.

Connections

Outlet

The outlet connection shall be a ¾ NH garden hose connection threads complying with ASME B1.20.7.

Inlet

Inlet connections shall meet the applicable requirements of the plumbing code.

Pressure

The devices shall be designed to operate from 25 psi to 125 psi (172.4 kPa to 862 kPa).

Temperature Range

The devices shall be designed for flow temperatures of 33.0 °F to 140.0 °F (0.6 °C to 60.0 °C).

Repairability

Devices shall be designed and constructed such that after installation, repair or replacement of the elastomeric parts shall be accomplished using standard tools. Construction shall permit field service without damaging or marring the surface of the device.

Atmospheric Vent

Atmospheric vent(s) (air inlets) shall be of a nonstandard plumbing connection.