Traditionally, fire detection in engine compartments has been based on heat detection. This has been logical in the light of requirements for operational reliability in a relatively difficult environment. Trials have been performed of the various alternatives, such as smoke and IR detection, but problems of dirt and wide temperature ranges have rendered these solutions unreliable. At the same time, the need for early detection of a fire has become ever more apparent, as understanding of the importance of early attack and the resulting savings in terms of reduced downtime costs and reduced repair requirements has increased.
The Vulcan project has developed a smoke detection systems for vehicles to permit detection of the very early stages of a fire, using equipment that can withstand the conditions encountered in an engine compartment. In addition, with analogue detection, various responses can be initiated, depending on the cause and progress of the fire. Practical trials under very difficult working conditions has led to a completely new approach to the detection of fires in engine compartments.
Traditionally, there have been two types of extinguishant containers: either in the form of a pressurized container in which nitrogen under pressure expels the extinguishant into a piping system when activated,or in the form of a normally unpressurized container which, when the system is activated, is pressurized from an external source, usually a smaller gas cylinder containing nitrogen under high pressure. Increasing restrictions on the transport of hazardous goods have progressively made the carriage of pressurized containers more complicated and expensive.
This applies very much also to the pyrotechnic actuators which are used in several systems on the market today. The Vulcan project has developed a container that is unpressurised during transport and normal use, but with the necessary pressure being generated internally in the container when the system is activated.
Testing And Verification
In all development projects, verification and testing are both important and resource demanding parts of the work. This applies both to careful and controlled measurements in a defined test environment and to actual verification of performance and reliability under postulated normal operating conditions. SP, with its high expertise in combination with its long experience of fire testing, has been an important partner in many different phases of the development work being carried out by the Vulcan project. In addition, the involvement of Volvo Construction Equipment provided an unique opportunity for long-term tests under actual operating conditions, while at the same time contributing with valuable views on how developed products may best be designed for production.
Processed Alarm Management
In traditional fire-fighting systems in vehicles, the response has often been of a single type, meaning that the system has operated (possibly after a brief delay), or after an alarm has been received by the central control equipment. Vulcan optimizes the various possible responses, depending on the conditions applicable to the vehicle at a given time. The combination of detection of both heat and smoke, while the system can also respond to other information from the vehicle, such as different driving conditions, permits the creation of a conditional matrix to provide different responses in terms of alarms and fire suppression actions.