Nitrogen Enriched Air (NEA) is produced by removing oxygen from the air using a unique separation membrane. NEA is generally used as a substitute for nitrogen cylinders in industrial applications, and also application as a fire suppression system is in progress. However, when NEA is used as a fire suppression system, the behavior in the compartment may be stratified due to the influence of buoyancy since the supply rate of NEA is limited compared to general gas fire suppression system that uses high-pressure gas cylinders. In this paper, experimental study using a model compartment was carried out to reveal the injection and outflow conditions of NEA in which oxygen concentration does not stratify were clarified. Furthermore, the NEA injection conditions were organized by the Overall Richardson number.

An experimental study on combustibility such as ignition and spread of spray-applied rigid polyurethane foam for thermal insulation (flame-retardant rigid PUF) was conducted. Polyurethane foams with the oxygen index of 23 and >26, which conform to JIS A 9526 Class A • 1H, were used. The main experimental items were as follows: TG-DTA thermal analysis, ignition with different igniters, ignition due to spatters (hot particles) generated by gas cutting, flammability on the thermal surface, flame propagation through pyrolysis gas/vapor, sample combination and flame spread (a small model experiment). As a result of the experiment on flame-retardant rigid PUF, the following is found. a) It is locally ignited and burned by gas-cutting spatters. However, it does not spread along the sample plate. b) Pyrolysis gas/vapor ignites when the hot surface temperature is 430°C or higher. c) Even flame-retardant rigid PUF can spread by combining sample plates.