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Ammonia leakage, dispersion and risk assessment


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Ammonia leakage, dispersion and risk assessment

Lightfoot Medal Winning Paper of 2017 as voted by members is now available for free download! Ammonia has been considered to be an excellent choice of refrigerant for industrial applications for more than 150 years even though it is toxic and flammable. It requires careful safety consideration in the design and operation of refrigeration systems and it has a good safety record. Ignition of ammonia is a very rare occurrence and is virtually unknown in systems which comply with recognised European Standards. However, compliance with the requirements of the Dangerous Substances and Explosive Atmospheres Regulations (DSEAR) 2002 in accordance with the EU ATEX Directives requires a different approach. A Joint Industry Project has sought to provide practical guidance to ensure ammonia refrigeration plants are fully compliant with DSEAR because the Health and Safety Executive (HSE) had determined that regulatory requirements are not always being fulfilled in the case of ammonia refrigeration systems. This paper provides an overview of the current legal framework and explains the procedure to be followed in classification of hazardous areas in accordance with IEC EN 60079-10-1. An approach using new software to model potential releases and calculate the hazard range, is described and new guidance is introduced for those involved in the design, construction, operation and maintenance of ammonia refrigeration systems.