Autoclaves are widely used to cure high performance polymer composite materials at high temperature and pressure. Pressurisation has conventionally been achieved by the use of compressed air systems. When air is used as the pressurising medium, there is some risk of a fire occurring within the autoclave. In extreme cases, explosions have been known to take place. Various causes for such fires are suggested. The use of inert nitrogen instead of air within the atuoclave eliminates the risk of fire. BOC Gases has developed a range of nitrogen based supply schemes to meet the production demands of the composites manufacturer. Nitrogen supply schemes use three basic modes of supply; liquid nitrogen and on-site noncryogenic generation by pressure swing adsorption or membrane. These options are described in deteil and the factors to be considered in deciding the best option for a given user are discussed particularly the demand pattern and the final oxygen required. In general terms on-site noncryogenic generation systems are lower cost per unit volume of gas produced but offer less flexibility than liquid nitrogen.
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