scope:

Description

This standard applies only to those devices classified as backflow preventers that are designed for installation on laboratory faucets on the discharge side of the last shut-off valve. These devices are not for use under constant pressure conditions. These devices consist of two independently acting check valves, force loaded or biased to a normally closed position, and between the check valves a means for automatically venting to atmosphere, force loaded or biased to normally open position.

Working Pressure

Devices shall be designed to operate within a working pressure of 0.0 psi (0.0 kPa) to a minimum of 125.0 psi (861.9 kPa).

Temperature Range

The devices shall be designed for a temperature range that includes 33.0 °F to 180.0 °F (0.6 °C to 82.2 °C).

Atmospheric Vent

a. The atmospheric vent shall be constructed so that it will open when the supply pressure is atmospheric or below.

b. The atmospheric vent shall be constructed so that under a backpressure condition it will open.

c. The atmospheric vent shall be constructed to provide vacuum breaking ability.

Repairability

a. The internal parts of the device shall be accessible for inspection, repairs or replacements.

b. All replaceable parts of the device of the same size and model shall be interchangeable with the original parts.