Risk analysis of LPG (liquefied petroleum gas) vehicles in enclosed car parks

A risk analysis is presented for an enclosed 30×30 m car park in which LPG (liquefied petroleum gas) vehicles are allowed to park. An event tree analysis is used to define 26 different incident scenarios and their probabilities. FLACS, a specialised CFD program, is used to calculate the formation of a flammable vapour cloud and its dilution by means of the ventilation system as well as the overpressures generated in a vapour cloud explosion. Existing empirical methods are used to calculate the overpressures generated by a BLEVE and the heat radiated by a fire ball and a jet fire. The simulations have shown that a release from a 70 l LPG fuel tank can lead to vapour clouds of up to 200 m3 that fill the entire height of the car park, while the explosion simulations have shown that such vapour clouds can lead to overpressures above 30 kPa in the entire car park. The ventilation simulations have shown that high flow rates of approximately 0.060 m3/s per m2 of car park floor area are necessary to rapidly dilute these large vapour clouds.

► Probabilities and effects have been calculated for 26 incident scenarios.
► FLACS is used to calculate the formation, dilution and explosion of vapour clouds.
► Empirical methods are used to calculate BLEVE, fire ball and jet fire effects.
► 200 m3 vapour clouds, which lead to overpressures above 30 kPa, may be formed.
► High flow rates of 0.060 m3/s per m2 are necessary to rapidly dilute these clouds.