Full-Scale Water Mist Design Parameters Testing

The overall objective of this evaluation was to further develop an understanding of the capabilities and limitations of water mist systems as applied to machinery space applications. The primary objective of this investigation was to evaluate the applicability of a local application test method being considered by the International Maritime Organization (IMO). An evaluation of the effects of mist spray obstructions on extinguishment capabilities was performed. The effects of compartment parameters (size and vent area), mist system parameters (system flow rate), and fire parameters (heat release rate, fire type, location, and degree of obstruction) were evaluated to aid in validating a scalability model. This model can be used to scale test results to other sized compartments. Local application water mist systems are capable of extinguishing spray and pan fires if they produce sufficient mist concentrations uniformly around the protected object. They do have limited capabilities against obstructed fires. The size of the obstruction and separation distance between the obstruction and the fire were identified as primary variables. A steady state model was validated that predicts compartment temperatures, oxygen concentrations, and critical fire sizes. Prepared in collaboration with Hughes Associates, Inc., Baltimore MD and Worcester Polytechnic Institute, Worcester, MA.