23-Backflow in Fire Systems: Balancing Flow Rate with Protection Peter McLennan

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1 Backflow preventers in fire systems. The Australian model Balancing flow rates with protection Wildfires: Did low water pressure hinder the fight? WA fires: Authorities warned about Yarloop's lack of water in 2015 Road construction causes low water pressure to fight fire Low water pressure hinders firefighters as blaze engulfs two weatherboard homes in Brisbane Obstructed pipes and valves What causes low water pressure? Obstructed pipes and valves Corrosion Water saving initiatives Head losses in the piping system 4 April

2 Corrosion Old wooden water mains Old wooden water mains Water saving initiatives Head losses in the piping system And backflow preventers. 4 April

3 AS/NZS Water Services is The basis of the National Plumbing & Drainage Code. Section 4, Cross Connection Control refers to the use of Backflow Prevention and outlines the Hazard levels Approved backflow products are identified in this section. Fire connections are considered a medium hazard connection where there are no additives used to suppress the fire When additives are used it is considered a high hazard connection Backflow scenario Fire hose reel assemblies in commercial buildings generally come off the drinking water supply. These are fitted with a DCV and registered and tested annually If within the hose length (36m) of a high hazard the rose reel must be fitted with an RPZ. 4 April

4 Different States interpret the Standards differently and in one area the fire service begins after the backflow preventer, and in others, it starts at the inlet isolating valve AS Fire detection, warning, control and intercom systems - System design, installation and commissioning - Fire Is concerned with flows, pressures needed for fire fighting and does not consider the drinking water requirements AS Fire detection, warning, control and intercom systems - System design, installation and commissioning - Fire Allows for non-plumbers to be used as it is not drinking water AS/NZS Water Services, says that drinking water must be protected from non-drinking water cross connections and wet fire systems are considered non-drinking water. AS/NZS Water Services, says that drinking water systems can only me installed and maintained by registered plumbers 4 April

5 Backflow preventers through definition work by differential pressure.anything in the flow line reduces the available pressure Needless to say, there is pushback from the fire fighters as pressure loss could mean the difference in whether the fire is extinguished or not. Needless to say, there is pushback from the fire fighters as pressure loss could mean the difference in whether the fire is extinguished or not. Testable devices commonly used in fire water applications RPZ, DCV, RPDA, DCDA, SCDAT, SCVT We need more pressure!!! Detector assemblies are used for (a) Identification of unauthorised flows (b) Billing for fire hose water use Detector assemblies are based on by-pass pressure drop being less than main valve and not on flow rates 4 April

6 Examples (from manufacturers published literature) 100mm DCV at 320 gpm has a head loss of 3 psi 100mm DCDA at 320 gpm has a head loss of 10 psi Unauthorised flows use ¾ or 1 water meters in the bypaass 100 SCDAT at 320 gpm has a head loss of 8 psi These figures are devices only and do not include strainers or isolating valves Billing flows use 11/2 or 2 water meters in the bypass High pressure drop across DCDA detector assys has led to an increased use of single Check valves SCVT and SCDAT Incorrect modifications Incorrect modifications 4 April

7 Balancing the needs for drinking water protection and ensuring adequate fire pressure needs reexamining..currently the only answer is additional on-site water storage and fire pumps The BPAA is working with major industry stakeholders to have the Australian Standards changed to allow USA style DCDA & RPDA Ongoing BPAA involvement Whilst fire water is connected to the drinking water, the focus must be on fire system management which includes maintenance Stakeholder positions on Codes and regulatory Boards Development of Guidebooks and educational material Take a leadership position at water industry forums Push for CPD with Plumber Licensing Boards Ongoing BPAA involvement Questions? President, the Backflow Prevention Association of Australia Inc. E: petermcl@brencliff.com Cell: April