By Admin on Fri 10 February 2017 in WRAS/Certifications
In this article we hope to help explain WRAS approval and its role in compliance with UK water regulations.
WRAS Solenoid Valve Approval.
What Is WRAS Approval?
Any water fitting, which when installed, will carry or receive water from the public mains water supply in the UK, must comply with the Water Supply (Water Fittings) Regulations or Scottish by-laws, specifically Regulation 4 (or Reg4). These require that a water fitting should not cause waste, misuse, undue consumption or contamination of the water supply and must be ‘of an appropriate quality and standard’.
Once WRAS Approval was the only practical way to demonstrate compliance to the water suppliers, although this is no longer the case (with Kiwa and NSF offering certification of equal standing) it does remain the most recognisable water fitting certification.
Product Approval: Whole products such as valves, boilers & showers undergo mechanical and water quality testing as laid down in the water regulations by a competent approval body. This type of approval demonstrates full compliance with requirements of the regulations and by-laws, provided the fitting is installed according to any conditions given with the approval.
Material Approval: Non-metallic materials & components, such as rubber sheet material & ‘O’ rings, undergo testing only for their effects on water quality. This type of approval demonstrates that the non-metallic material/component does not itself contaminate the water and therefore satisfies this particular requirement of regulations and by-laws.
Solenoid valves certified by WRAS as meeting Reg4 for mains water applications are available in most sizes from 3/8" - 1 1/4" BSP thread for 2/2 latching, 2/2 way normally closed and 2 way normally open. WRAS solenoid valve Certification and Approvals are only available to water solenoid valves that fully conform to the water regulations, although interestingly enough this only really applies to the non metallic parts of any solenoid valve such as the elastomer diaphragms, O ring seals, gaskets and other seals that come into contact with the water passing through the solenoid valve and typically must comply to BS6920 (test for water quality).
In the past NBR (Nitrile Buna Rubber) was the accepted standard seal material however EPDM (Ethylene Propylene Diene Monomer) and silicone rubber have now surpassed NBR seals for drinking water as they have a reduced effect on the taste of the water passing through the solenoid valve. Silicone being derived from silicon rather than oil is becoming more popular as a material for use with potable water. The other materials of construction of the solenoid valve such as brass and various grades of stainless steel are of no real concern so long as there are no harmful chemicals present or high content of potentially harmful substances such as lead and are of course totally free from potential internal or external leaks and fit for purpose.
Compliance with the water regulations (by-laws in Scotland) is the key issue rather than the name of the test/certification organisation.