Protecting Australia’s Heritage – The Story Bridge

10 March 2016


Completed in 1940, Brisbane’s Story Bridge is the longest cantilever bridge in Australia and was heritage listed in 1992.  The Story Bridge, which has a length of 1072 metres, took 5 years to build and was constructed with over 12,000 tonnes of structural steel, 1,650 tonnes of reinforcing steel and over 1,500,000 rivets.  The bridge’s 105,000 square metres of steel surface area is painted continuously and a new coat is completed every 7 years using 17,500 litres of paint.  

The bridge carries 97,000 vehicles daily and any event that interrupts the flow of traffic would have serious consequences for Brisbane’s travelling public.  The paint storage warehouse is located under the bridge at Kangaroo point and was identified as a major hazard and risk if a fire was to occur.  The paint storage warehouse has now been protected by Fire Protection Technologies with a hybrid nitrogen/water mist Vortex fire suppression system installed by Fire Services Queensland Pty Ltd.

The Vortex fire suppression system is unique in that it does not require a fully sealed room to provide effective fire suppression.  The Vortex system produces water droplets of 10 micron in diameter and is combined with a nitrogen atom.  This combination produces a homogenous mix of water droplets with almost the same buoyancy as natural atmosphere resulting in an extinguishing atmosphere that does not tend to “flow” out of the protected enclosure as other “heavier than air” gases do.  The system “emitters” or discharge nozzles combine water and nitrogen at high velocity and low pressure creating
a uniform blend of water and nitrogen; water is introduced to a jet stream of nitrogen at supersonic speed, then delivered with the nitrogen into the protected space at around 60 Km/hr.
 
The homogeneous mixture of water droplets and nitrogen gas is propelled with enough energy to overcome the drag effect that has limited the effectiveness of traditional water mist systems and with such small quantities water being utilized, very little wetting of the enclosure occurs.