Améliorer la sécurité des systèmes à ammoniac (en anglais)

Dans sa présentation lors de la Conférence 2013 de l'IIF sur les technologies frigorifiques utilisant l'ammoniac, A. Pearson conclut que les risques liés à l'ammoniac pourraient être atténués grâce à une conception adaptée des systèmes, basée sur des données réelles en termes de santé et de sécurité.
Andy Pearson’s keynote presentation* at the 2013 IIR Ammonia Refrigeration Technology conference, reviewed a series of industrial accidents in ammonia plants and concluded that even though ammonia is theoretically hazardous, it is by far not the major cause of accidents and incidents.

These were the result of:
. mistakes made while performing a maintenance operation by an insufficiently trained person;
. the use of an inherently unsafe procedure;
. issues caused by several modifications to the original design of a system introduced over several years;
 . an unexpected and sudden failure of equipment taking an operator by surprise.

All these examples tend to underscore the threat residing in bad practices and flawed systems.

A review of accident statistics over a 12-year period for a company whose activities include the construction of pressure systems in factories and on site for ammonia, carbon dioxide and fluorocarbon systems did not list toxicity or flammability of ammonia in the list of accident circumstances.

A. Pearson therefore considers that safety hazards related to ammonia could be mitigated through the correct design of systems, based on real health and safety issues.
He advocates a risk-based approach and claims that our current standards are too high in some areas and too lax in others and that making safety standards more stringent and hard to follow might be counterproductive. This would entail looking at possible scenarios and specific risks.
As a result for example, the refrigerant charge limits would no longer be based on the total amount of refrigerant within the plant, but instead on the total amount that could accumulate in the occupied space, with suitable control measures such as gas sensors and isolating valves.

* Making ammonia systems safer, A. Pearson

This paper can be downloaded via the IIR’s Fridoc database (free for IIR members within the framework of their quota of free downloads).