Fire extinguisher

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The extinguisher is made up of several components, the most visible being the carbon fibre pressure vessel, or main body of the extinguisher. Inside this vessel is a bladder or balloon which holds the extinguishant material itself - a liquid chemical stored under pressure that emerges as a gas when the system is activated and the contents discharged.

The system is ‘fired’ when a remote charge of compressed air is activated and fills the space between the pressure vessel and the bladder. This effectively compresses the bladder, forcing the extinguishant through a manifold in the body and along special tubes mounted in the chassis to eventually discharge through small nozzles. Two of these nozzles are mounted on the rear bulkhead of the chassis and point directly at the engine compartment, and a further nozzle is mounted in the cockpit.

The system can be fired in one of two ways. Internally, the car has a button on one of the switch panels which, when pushed by the driver, will activate the system. This button has its own battery so that it remains totally independent of the car’s power system - something which may be compromised in an accident.

Alternatively, the system may be activated externally by a member of the emergency services. This is achieved via a small handle mounted on the right hand side of the roll hoop. This handle is attached to the main power box of the car via a cable, which is also attached to the extinguisher firing mechanism. When this handle is pulled, the car’s electrics are immobilised, killing the engine. At the same time, the extinguisher is activated.

When the extinguisher is ‘fired’, 95per cent of its contents must be discharged at a steady pressure in not less than 10 seconds and not more than 30 seconds in accordance with the FIA Technical Regulations, Article 14.1. The extinguishant itself comes from independent suppliers who are licensed by the FIA to provide all Formula 1 teams with extinguishers that will operate in the unique environment of a sophisticated racing car. The fire extinguisher has a finite life, and is deemed to be no longer fit for use after a period of two years. Should a bottle be discharged however, it can be re-charged using a refill kit supplied to the teams by the manufacturer.

Each new car has a custom-designed installation, so the extinguisher seldom reaches its 'sell by date'. The bottle design will almost certainly not change during a season but, as the next new car is being designed, the bottle will change to match its surroundings. The bottle is positioned in the keel area of the chassis, which is directly under the driver’s knees. To give an idea of size, the bottle is cylindrical and measures 150mm in diameter and 250mm in length.

The fire extinguisher is an important piece of equipment on which, fortunately, drivers must rely very infrequently. But it helps to know that there’s a silent partner there and that it would do the job given the opportunity.

Technical Specification

diameter: 150 mm
length: 250 mm
weight: 4 kg

Source: McLaren Mercedes