Hangar Pop Up Sprinkler


The Australian Defence Force is constantly evolving as new assets are introduced. With the arrival of a new piece of equipment comes the need to upgrade support services. When the Royal Australian Navy introduced new MRH90 helicopters to its South Coast base, HMAS Albatross, the ‘ripple effect’ extended to the unique asset protection system in its aircraft hangars.

The underground pressurised nozzles pop-up from below the floor of the hangar when activated and discharge retardant over the aircraft. Since the original system was installed the size and shape of the aircraft had changed dramatically. This required a completely new spray pattern.

The scope of work also required the new delivery unit to be capable of operating in a harsh environment. This was because the heavy aircraft roll over the pop-up nozzles and hangar cleaning practices have changed. In previous years if there was a spill, such as aviation fuel, the floor would be flooded with water to clean it away. These days, with strict environmental regulations in place, spills have to be dealt with in a more controlled and localised manner. This may result in the components being in contact with volatile substances for longer whilst the mopping up procedure is carried out. In addition, although every care is made to keep the hangars clean the nozzles are exposed to wind-blown debris and dirt.

Archer Operations Director Russell Byrne explains the scientific approach that they had to take with this project,

“A fire suppression unit is much more than a system pumping out water or retardant in all directions to neutralise an incident. There are strict operating standards. Our new generation nozzle had to deliver a constrained amount of water into a defined virtual space. The MRH90 helicopter fuselage sits lower to the ground than the previous aircraft assets. It is a reduction in height from 900 millimetres ground clearance to 450 millimetres. The width of the spray pattern remained unchanged at 7.5 metres. So, the water had to reach a certain point and not go past it.”

Archer studied the existing piping system and pump rates. The new nozzle would have to operate under the same flow rates as the current system. The ‘virtual space’ was calculated into the design of the new nozzle using sophisticated 3D CAD/CAM software. A clever inverted angled deflector centre was created to disperse the water. It differed a lot from the original unit. This feature doubled by adding to the ruggedness of the design.

Archer assessed the manufacturing of the original OEM components – which were aluminium investment castings – and determined that by machining the new versions from billet they would have even greater strength.

The CAD file was posted to one of Archer’s multi-axis machine centres and a number of prototypes were made. From here they were assembled and taken to the test laboratory which is part of Archer’s world-class Manufacturing Centre of Excellence. A test bench was set up to check water deflection angles and dispersant range. Within a short period of time the optimum specifications had been achieved and the nozzles were installed at the air base.