Specification & Installation pitfalls “Getting it right to ensure safe drinking water”

Backflow ‘101’ Backflow is the undesirable reversal of flow in a piping system (0h, if backflow prevention was this easy!)

Why do we need backflow plumbers? A common misconception…….. There is no need for specially trained backflow plumbers because all Australian plumbers are trained, skilled operators that understand the water supply and the hydraulics of a plumbing system.

Backflow prevention protects from this!

Australian Standards Plumbing Code of Australia (PCA) 2015 AS/NZS The National Plumbing & Drainage Code refers to the use of Backflow Prevention and outlines the Hazard levels AS/NZS Backflow Prevention Devices – Materials, Design and Performance AS/NZS Backflow Prevention Devices – Air Gaps and Break Tanks AS Backflow Prevention Devices – Field test and Maintenance

Installation AS/NZS Only stipulates general installation requirements. For example, use of line strainers, ground clearance for relief vents, use of isolating valves and access requirements. Each manufacturer provides detailed installation Instructions with their product. Following these instructions protect you in a warranty claim and ensures the device operates properly.

Products often incorrectly installed

Hose Connection Vacuum Breaker Installation requirements Must have free ventilation at all times. Shall not under normal operation, be subject to constant pressure. Have no isolation valves located downstream of the vacuum breaker Why? If left pressurised, seat disc may vulcanise to seat and not operate allowing a cross connection to occur

Hose Connection Vacuum Breaker Permanently attached & under constant pressure

Dual Check Valve with Atmospheric Port “DCAP” Installation Requirements The DCAP must be installed in an accessible location to facilitate periodic maintenance. The device must be installed in the horizontal position. The location selected should have adequate drainage for vent discharge. The device should never be placed where it may be submerged in standing water..

Dual Check Valve with Atmospheric Port “DCAP”

Pressure Vacuum Breaker “PVB” Installation Requirements Pressure vacuum breakers should be installed at least 300mm above the highest piping or outlet downstream of the device and with the supply line connected to the bottom of the device. Install the device in an accessible location to facilitate periodic field-testing and any required maintenance. Install where the spillage of water does not cause damage or nuisance.

Is it higher than outlet piping?

Where is the supply line connected?

Accessible for testing and maintenance

Dual Check Valve “DUALCV” Installation Requirements The Dual Check Valve must be installed in an accessible location to facilitate periodic maintenance. The device can be installed horizontally or vertically as long as access is allowed for ease of maintenance. A clearance between the lower most portion of the device and the floor should be provided for ease of maintenance.

Dual Check vs. Double Checks Similarities Both have 2 Independent Checks Both must hold 7 kPa or greater Both Protect against non- health hazard pollutants Differences DCV is approved by AS2845 as a Backflow Protection Assembly for Medium Hazard Dual Check is approval only for Low Hazard applications Dual Check is generally not installed with test cocks or shutoff valves Dual Check - Generally NOT testable inline

DCV vs. DualCV Flow Comparison (20mm) Rated Flow 115 L/min Rated Flow 57 L/min VS. Biggest Difference is the flow comparison Dual Check Valve has much lower rated flow

Double Check Valves “DCV” Installation Requirements The DCV must be installed in an accessible location to facilitate periodic field testing and maintenance. The device may be installed in either the horizontal or vertical flow up position. A clearance between the lower most portion of the device and flood grade or floor should be provided for ease of maintenance.

Tough To Test & Maintain

Vertical is acceptable

Upside down for DCV is acceptable

Incorrect modifications

Reduced Pressure Zone Valve “RPZ” Installation Requirements The RP must be installed in an accessible location to facilitate periodic field testing and maintenance. The location selected should have adequate drainage for relief valve discharge. The device should never be placed where it may be submerged in standing water. The device must be installed in the horizontal position. Clearance between the lower most portion of the device and flood grade or floor should be provided for ease of maintenance.

There’s an RPZ in there somewhere…

Remember it needs adequate drainage…

Hope you never have to work on it!

It’s Installed horizontally!

Needs to be Horizontal!

How do you test this?

Relief Valve Drainage All Backflow preventers that can dump water must be installed where spillage of water does not cause damage or nuisance. This can be done using safe trays, tundishes or on RPZs proprietary air gap fittings.

For example, a 50mm RPZ when installed in a pressure of 700kPa can dump 720 litres per minute

So how much water is that? You could empty an Olympic sized swimming pool in less than 6 hours!

So how much water is that?

Support & Protection AS Clause 5.6 ‘Support and fixing above ground’ Stipulates that water services installed above ground shall be retained in position by brackets clips or hangers. It is important to consider this when installing the device

Adequate support is required!

Well installed…almost a great installation

Well supported

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CagesCages

EnclosuresEnclosures

Questions?Questions?