Evaluation of the Potential Failure Modes for Gaseous Agent Fire Extinguishing Systems Installed within the Protected Space

摘要

A full-scale fire performance evaluation was conducted to assist the USCG in developing a position on the practice of installing gaseous agent fire extinguishing system components (i.e., agent cylinders and control valves) within the space they are protecting (i.e., machinery spaces). Testing was carried out to identify the potential failure modes of the system and its components. The evaluation assessed the survivability of a number of halocarbon and inert gas fire suppression system components against a range of exposures/conditions. The results suggest that a component containing plastic or rubber parts is likely to fail if the exposure exceeds 15 kW/m2 and the energy dosage exceeds 9 MJ/m2. An analytical assessment of agent storage cylinders (various extinguishing agents and cylinder sizes) conducted during this investigation suggests that the pressure relief valves in the cylinders would vent the extinguishing agent with approximately the same exposures/conditions that caused failures of plastic or rubber parts. In addition, one test was conducted to determine if the loss of an agent cylinder in the space (implied in SOLAS as an acceptable consequence) would prevent the system from extinguishing the fire. The results show that the loss of an agent cylinder will render the system ineffective (not able to extinguish the fire). As a result, the system needs to be designed and installed in a manner to ensure that the design concentration of agent (1.3 times the minimum extinguishing concentration) is available at the time the system is activated.