RPZ Backflow Prevention Devices

MASTERFLOW SOLUTIONS’ CWMA make-up assembly comprises a backflow prevention valve, two isolation valves, y-strainer and, if required, a pressure reducing valve. This valve consists of a reduced pressure area between two check valves (R.P.Z.) and is approved to AS2845.

It is available in sizes 15mm (½”), 20mm (¾”), 25mm (1”), 32mm (1¼”), 40mm (1½”) and 50mm (2”). They are supplied in kit form with unions fitted and gaskets for quick assembly.

Overall length of the CWMA-15 is 505mm. Maximum inlet pressure is 1000kpA. Material of construction is brass.


The backflow prevention valve can be used in all systems where there is danger of the drinking water supply system being contaminated. It prevents an accidental reduction in the pressure in the distribution system from causing the contaminated water in user installations to return and by mixing change the original drinking qualities.



The equipment is installed horizontally. Before installing the backflow prevention valve and the strainer the pipe should be cleaned with high-capacity water jet. In order to protect the public supply system the backflow prevention valve is installed after the water meter to protect supplies for sanitary purposes in the internal system it is fitted at the limit of the areas in which contamination can take place as for example centralized heating systems, garden watering systems etc.

The Reducing Valve will be necessary on all closed circuits to safeguard the pressure tank and other equipment that have pressure limitations. For those systems MASTERFLOW SOLUTIONS can supply a range of pressure tanks fitted with safety valves. Enquire with our sales staff.


As the backflow prevention valve is an item of equipment used to ensure the safety of domestic water supplies it must be inspected periodically. The first sign that the equipment is not functioning properly, which is generally associated with the presence of foreign bodies or impurities, will be indicated by a permanent leakage through the discharge vent.

This loss is just an initial warning sign and does not completely jeopardize the safety of the check mechanism but means that the unit should be dismantled and the equipment and the upstream filter should be cleaned by qualified personnel. Local authorities should be contacted for the required frequency of inspection.

  • R.P.Z Valve - prevents backflow.
  • Isolation Valves – allows system to be isolated for cleaning for straining and routine service of R.P.Z.
  • Vent – for discharge to sewer. Indicates R.P.Z valve needs checking.
  • Pressure Reducing Valve – holds the pressure in the system at a pre-set pressure.
  • Gauge – indicates pressure of system.
  • Y-Strainer – collects foreign particles. Protects R.P.Z.

We look forward to the opportunity of assisting you.

Please contact us with your requirements; we are always ready to listen.