Passenger and freight trains provide a variety of fire risks, dependent on the type of train, and operating conditions. Train engine compartments have traditionally been fitted with fixed fire 3 systems, but passenger compartments and driver's cabins have relied on manual intervention with portable fire extinguishers.
In diesel-engine trains the fire risk in the engine compartment normally involves the accidental release of diesel or lubrication oil onto nearby hot surfaces such as a hot exhaust manifold. On electric trains the risk is from overheating of electric motors or ancillary equipment.
The objective of a fixed fire protection system in a train is therefore to extinguish engine fires, and suppress any fire in the passenger compartment and driver's cabin without comprising safety of staff or passengers. Systems must be robust enough to withstand constant movement, vibration and possible vandalism. They should not harm the environment, nor damage sensitive electronics and electrical equipment.
Engine compartments in trains have traditionally been protected with Halon or foam systems. Some of the Halon systems still exist, but many have been replaced with other gaseous agents.
Fixed fire protection systems are not common in passenger compartments, but conventional low-flow sprinklers have been fitted in rare instances.
As Halon has continued to be phased out for environmental reasons alternative gaseous agents have been used, although systems do not provide cooling to prevent re-ignition and may be ineffective if enclosure integrity is not maintained.
Foam systems can damage surrounding equipment and special clean-up procedures are needed. In passenger compartments conventional sprinklers have not proved popular as the amount of water needed to be effective has meant much additional weight.
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