Draft Details

1.1 General

This Standard covers reduced pressure principle (RP) backflow prevention assemblies (herein referred to as the “assembly”) that are used in potable water supply systems to prevent cross-connections.

1.2 Sizes

This Standard applies to nominal assembly sizes of 1/4, 3/8, 1/2, 3/4, 1, 1 1/4, 1 1/2, 2, 2 1/2, 3, 4, 6, 8, 10, 12, 14, and 16 in (DN8, DN10, DN15, DN20, DN25, DN32, DN40, DN50, DN65, DN80, DN100, DN150, D200, D250, D300, D350, and DN400).

1.3 Application

RP assemblies are intended for use in the isolation of high or severe hazards where contaminated water can flow back into a potable water distribution system.

1.4 Description

RP assemblies consist of two independently acting check valves, internally force loaded to a normally closed position and separated by an intermediate chamber (or zone) in which there is a hydraulically operated relief means for venting to the atmosphere, and internally force loaded to a normally open position. These assemblies are designed to operate under continuous pressure conditions. The assembly includes two properly located, tightly closing shut-off valves and properly located test cocks as per Clauses 4.4.4.5 and 4.4.4.4.1.

1.5 Terminology

In this Standard, “shall” is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard; “should” is used to express a recommendation or that which is advised but not required; and “may” is used to express an option or that which is permissible within the limits of the Standard.

Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material.

Notes to tables and figures are considered part of the table or figure and may be written as requirements.

Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application.

1.6 Units of measurement

SI units are the units of record in Canada. In this Standard, inch/pound units are shown in parentheses.

The values stated in each measurement system are equivalent in application; however, each system is to be used independently. Combining values from the two measurement systems can result in non-conformance with this Standard.

All references to gallons are to U.S. gallons.