Stop the damage Testing a hot and cold-water service post installation has become increasingly problematic due to the increased use of mixers, Master Plumbers’ technical Advisor, Aaron Bridger, explains. In the past it was easy to leave out a set of washers in a breech to ensure that the shower outlets and hot-water lines were pressure tested. This testing also provided an opportunity to flush lines of any foreign material. Equally, this testing is important for mixers (as well as limiting valves, etc). It can eradicate the potential for damage. As outlined in AS/NZS 3500.1, a hydrostatic test is required to be performed. The testing clause states, water services shall not show any leakage when subjected to a hydrostatic pressure of 1500 kPa for a period of more than 30 minutes. Our issue arises with the 1500 kPa figure. Most mixer cartridges cannot be subjected to pressures greater than 500-600 kPa. There are some that allow up to 1000 kPa but very few allow the full 1500 kPa required to satisfy the standard. When the cartridges are over pressurised, it often leads to damage of the cartridge, which requires cartridge replacement. Furthermore, there are some piping systems that are available that have their own testing procedures. Failure to achieve the required pressure (or in some cases too much pressure) may result in no coverage of product warranty.
14 | Australian Plumbing Industry Magazine | Summer 2021
So, to protect mixer cartridges from either over pressure or damage from flushing through foreign matter, Danial from Keralton Plumbing thought there had to be a solution. He created a prototype of what is now known as the Test Piston. There have been many modifications to the design to get it to the point that the team at Keralton Plumbing are happy to bring it to the market. The Test Piston is straight forward and easy to use. As shown in the images, it is installed by removing the current mixer cartridge. The rubber ring is placed on the bottom of the plastic piston and installed into the cartridge housing. The test piston in then secured into the housing with the existing locking nut. With the piston in place, you are now ready to test. You can now safely and confidently test to 1500 kPa, ensuring you comply to the required standard and maintain your warranties and insurance. The Test Pistons are sold exclusively by Keralton Plumbing. They are available in both 34mm and 38mm and come in packs of 10. For more information, email admin@keraltonplumbing.com.au
