A Comparison of Various Fire Detection Methodologies in Transit Vehicle Engine Compartment Fire Protection Systems

Distinctly different fire hazards exist within the engine compartment of a transit vehicle and various detection methodologies may be employed to detect fire events arising from these hazards. The engine compartment presents a particularly challenging environment and it is important to select the correct methodology to ensure timely detection response in the early stages of the development of a fire whilst minimizing nuisance alarms. The choice of the correct detection methodology for a specific fire hazard is therefore determined by the suitability of the methodology for the detection of the anticipated fire event within the environment in which it is required to operate. This paper presents experimental data to demonstrate the variation in the response times of different detection methodologies in the presence of common fire events in the form of simulated flaming fuel fires and a simulated electrical fault in the form of an overheated electrical cable. The data presented relates to experiments conducted within a simulated transit vehicle engine compartment and includes the impact of environmental parameters, such as cooling due to high airflow rates, on detection response times. The paper will conclude with the lessons learned from this testing, and provide insight into key aspects for successful detection of the different fire hazards in this demanding application.