HSE press release - E134:03 - 17 July 2003
A research report assessing the effects of flash fires on building occupants has been published by the Health and Safety Executive (HSE), as part of a programme to develop risk-based tools for land-use planning.
The report considers the likelihood of secondary ignition of building interiors, based on the incident heat flux from a fire and the duration of exposure, and assesses the proportion of occupants who may not escape the secondary fire.
A key finding is the increased probability of fatalities due to multi-point ignitions where fire engulfs a whole building, compared with that for single-point ignitions, where only one building elevation is exposed to the initial fire.
The report suggests that the probability of death from secondary fires, initiated by a flash fire, is approximately 2% in an office building and about 21% in a dwelling at night.
This research was commissioned by HSE's Hazardous Installations Directorate (HID) and carried out by W.S Atkins Consultants Ltd., managed by the HID Methodology & Standards Development Unit. It will be used by HSE in assessing safety reports submitted under the Control of Major Accident Hazards Regulations 1999.
'Effects of flash fires on building occupants' (Research Report 084) is available on the HSE website at http://www.hse.gov.uk/research/rrhtm/index.htm.
1. A flash fire can occur following loss of containment
incidents involving volatile or "flashing" flammable
liquids. Unless ignition occurs immediately there is a possibility
of a flammable vapour cloud forming that could later ignite at some
distance from the source. Following ignition, the flame front can
"flash back" to the source.
2. When modelling the effects of such fires, for the purposes of
risk assessment, the usual assumption is that any unprotected
people caught in the open air by a flash fire flame front will be
killed but that the proportion of fatalities is significantly lower
for those sheltered within buildings.
3. The report and the work it describes were funded by HSE but its
content, including any opinions and/or conclusions expressed, do
not necessarily reflect HSE policy.
All enquiries from journalists should be directed to the HSE Press Office
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