Example Facility Ranking Process

Collect Data on Quantities and Condition of Hazardous Material Use the list of hazardous materials contained in OSH A CFR1910.119, or other similar lists published by industry associations and regulators worldwide. Data on plant sections, quantities of hazardous material, and their storage conditions can be gathered in a number of different ways, depending on what information is available. 

Different materials pose different hazards, including thermal radiation, explosion overpressure, and toxic and flammable vapor clouds. Some materials pose only one hazard, while others may pose all four. For the purposes of ranking facilities you will need to estimate the laigest area affected by the potential hazards. You can arrive at such an estimate by calculating the greatest downwind distance to a particular level of hazatd. The following thresholds are commonly applied  

Thermal radiation 5kW/m (severe bums to bare skin within 30 seconds) Explosion overpressure 0.1 batg (minor structural damage, injuiy from falling masonry, glass etc.) 

Toxic hazard IDLH (immediately dangerous to life and health) concentration Flammable vapor cloud Lower flammable limit 

Each of these criteria represents a level at which injuries can occur. In addition, some other criteria may be appropriate, for example where existing hazard calculations are in use, corporate policy defines different standards, or local regulation sets criteria. 

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