HACC can help define and characterise your operation’s Basis of Safety through Explosion Prevention measures in order to meet your organisation’s risk tolerability or acceptance. HACC will assess Explosion Prevention in the following ways:

  • Remove the Flammable Material – In terms of gases, vapours and mists, removing flammable materials could be anything from substituting the flammable substance with something, which is not flammable, operating above its Upper Explosive Limits (UEL) or below its Lower Explosive Limits (LEL) concentrations with air (or oxidant) and controlling operating temperatures below a flammable liquid’s flash point etc. For dust, this is more difficult as dust tends to move from one place to another and accumulate in layers, which can be regenerated into a dust cloud via airflow or vibration etc. Minimum Explosive Concentration (MEC) can be determined and used, especially in conveying or extraction systems. However, as dust clouds are never homogeneous, MEC cannot be used as the sole Basis of Safety as the dust concentration can never be guaranteed.
  • Remove the Oxygen from the Atmosphere – In order to develop a Basis of Safety by removing the oxygen from the process, the Limiting Oxygen Concentration (LOC) for dusts and Minimum Oxygen for Combustion (MOC) for gases, vapours and mists needs to be defined. In order to maintain the Basis of Safety, the oxygen concentration in the process in question needs to be maintained below the LOC for dusts and MOC for gases, vapours and mists.



Note: As with all systems that have a Basis of Safety that depend on a specific value or metric (e.g. temperature, pressure, concentration etc), it is necessary to measure and monitor that value or metric within the process either continuously or at a frequency that is sufficient to maintain safety.

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