Performance Requirements for Backflow Preventers with an Intermediate Atmospheric Vent
|Publication Date:||11 March 2009|
The devices covered by this standard are those which have functional capabilities for preventing both back-siphonage and back pressure and which can operate under continuous or intermittent pressure conditions. These devices have two (2) independently operating check valves separated by an intermediate chamber with a means for automatically venting it to the atmosphere and can be installed in the horizontal, vertical up or vertical down orientations. The check valves are force loaded to a normally closed position and the venting means is force loaded to a normally open position.
Inlet and outlet pipe sizes are 1/4 to 3/4 NPS (8 mm to 20 mm) inclusive.
Minimum Pressure Rating
The device shall be designed and constructed for a working pressure of at least 150.0 psi (1034.2 kPa).
The device shall be designed and constructed for normal flow temperatures of 40.0 °F to 210.0 °F (4.4 °C to 98.9 °C) and an emergency back pressure temperature of 250.0 °F (121.1 °C).
Manufacturer's advertised maximum flow rate.