With effect from 18^th April 2008 the advice on Water Supply Industry requirements for RPZ valves in the WRAS Information and Guidance Note 9-03-02 Issue 3 is withdrawn.  A copy is retained in the "Publications Withdrawn" section of the website for reference.

Publication of revised installation and maintenance requirements

Revised Water Supply Industry requirements for these valves are set out in the WRAS Approved Installation Method AIM 08-01 Issue 1 which Water Suppliers have been implementing for some time.

Test method for low differential pressure RPZ valves

The AIM permits (paragraph 7.2.2) a low differential pressure test criterion for some types of valves that have a 'soft' spring in the No. 2 check valve.  The usual field test equipment is unlikely to be capable of detecting this low differential pressure and an alternative field test procedure has been developed using a manometer.

As a service to RPZ testers, WRAS is preparing a list for the website of those makes and models of RPZ valves for which the lower differential pressure test is appropriate.  Manufacturers who have valves which qualify for inclusion in this list are asked to contact the Scheme.

The AIM requires testing of RPZ valves at commissioning and at regular intervals, using testers who have been approved by the Water Suppliers.  A list of Approved Testers is maintained by WRAS on behalf of the Water Suppliers.   If you have undertaken suitable training and have passed an assessment in testing valves, and wish to be included in this list, please contact the Scheme.