Speed saves lives

What do you do if you have less than a minute to get your firefighting vehicle to a fire whatever the weather conditions or level of visibility? Sue Chamberlain reports

This is the dilemma that faces aviation firefighters day in, day our: In an aeroplane fire scenario survivors have up to 90 seconds before they are likely to die, most from asphyxiation, so speed is of the essence.

At the same time, the vehicle needs to have excellent handling capabilities. An ARFF truck is rarely simply traveling in a straight line, but spends 90 per cent of its time braking, accelerating and concerning as it negotiates the labyrinth of busy runways and roads at an average airport.

Colet trucks, manufactured by JRI Inc, California, USA, builds a vehicle to do just that. Chief Engineer Ralph Colet, spoke to Fire International about the design rationale behind the Colet K-15 Jaguar. The first thing to understand, says Mr. Colet, is exactly what the customer's needs are, then think along the lines of a Formula One racing car and you will understand his starting point.

 

The K-15 Jaguar can accelerate from zero to 80kph in less then 14 seconds. Added to this, it has an active-reactive suspension system integrated with a stainless steel monocoque chassis for greater mobility, performance and safety. With this type of construction the 6,819 litre water tank is integrated into structure of the whole vehicle, balanced on a computer controlled cushion of air and hydraulic fluid so that driving conditions are constantly compensated for. The centre of gravity is lower too, by about 1 to 1.5 m, adding to its stability at speed. Ralph Colet described how, at recent trials, his driver was advised that, when approaching a particular 90° bend, the fastest safe speed for conventional trucks was approximately 16-25 kph. The K-15 Jaguar took these same bends at between 65 and 80 kph.

 

This means, that the K-15 Jaguar series can get to a fire faster and more safely than any other design, and seconds make all the difference to the number of lives saved at a post-crash site.

 

Speed and stability are, of course, essential, but so is the ability to knock down the fire in questions as quickly and safely as possible.

 

The K-15's firefighting system has a high-efficiency, computerised foam proportioning system. Most conventional crash trucks are usually only be able to fight fires face on, while the Colet carries a lightweight boom mounted with a powerflow of between 1,100 and 3,790 litres per minutes and a variable range of 92 m plus that can turn through a 360° arc, and be adjusted for high or low delivery. The distinctive shape of the front end of the truck is designed for maximum visibility, which is also essential for optimum visibility, which is also essential for optimum visibility when traveling at speed around the airport as well as at the incident site.

 

Ralph Colet pointed out that there are a number of engineering reasons why the K-15 Jaguar has this unusual shape. A major consideration in the design was operator safety, and this cockpit provides the occupants with a high level of protection. It has an integrated crash cage, all bonded glass and progressive crumple zones in the vent of high-speed impact with an immovable object such as a brick wall. Even the design of the steps and the doors, which open like a wing, are designed to minimise the possibility  of accidents on leaving and entering the vehicle.

The cab is more like a helicopter cockpit than a crashtruck. The K-15 is capable of coping with most weather conditions too. As Mr Colet points out, crews can sometimes be called out in temperature as low as -22°C. If you have less than one minute to get to and start knocking down a fire, you do not want to wait while windows defrost. The K-15 de-ices with five defrost unit going, and also has air conditioning for desert conditions.

Within weeks of Atlanta International Airport, USA acquiring the K-15 it was put through its paces when a DC9, full of fuel, burst into flames on take-off. One engine exploded, rupturing the main fuel line with 60,000 litres of fuel in the wings. The K-15 arrived on the scene before full evacuation had been completed, in under a minute, knocking the fire down immediately. One of the busiest airports in the world, it has a fleet of 11 Colet crash trucks. On average there are seven call-outs per day. During this time (the equivalent of ten year's use) there has not been single chassis system failure, and the K-15's downtime is unequalled.

The Colet K-15 Jaguar is also used by the US Air Force. Colet and his team are continually working on research and development to improve their products, and will customise designs to suit client's requirements.

Ground Zero - a new perspective, February 2002 No. 193, Fire International, United Kingdom.

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