BS ISO 19706:2011 pdf download – Guidelines for assessing the fire threat to people 4 General principles 4.1 Fire effluent and escape time 4.1.1 Life safety in a fire is greatly enhanced if the time available for occupants to escape exceeds the time required for them to escape and is threatened if the time required exceeds the time available. 4.1.1.1 As specified in ISO/TR 13387-8, the time required for escape includes the time from ignition of a fire to its detection, the time from its detection to an evacuation warning to occupants, an occupant’s pre-movement time (the time between becoming aware of an emergency and initiating egress) and the actual travel time to a place of safety. 4.1.1.2 The time available for escape is the interval between the time of ignition and the time after which conditions become untenable, such that occupants are unable to take effective action to accomplish their own escape to a place of safe refuge. Guidelines for estimation of the time available for escape are specified in ISO 13571:2007. It involves procedures to evaluate the life threat components in a fire hazard analysis, e.g. toxic gases, heat and smoke obscuration, in terms of the status of exposed subjects at discrete time intervals. The time at which occupants’ exposure exceeds a threshold criterion represents the time available for escape. Users of ISO 13571:2007 have the flexibility to set such criteria according to their chosen life safety objectives. Thus, an estimated time available for escape might or might not be equivalent to an ASET (available safe escape time). 4.1.2 The quantity and nature of the fire effluent are prime factors in estimating the time available for escape. The effluent nature is a function not only of the product from which it is generated, but also of the conditions under which the product participates in the fire and the nature of the fire. 4.2 Effects of fire effluent on people During and following a fire, the products of combustion can have lethal and sub-lethal effects on occupants of the facility and responders to the fire. The severity of the effects depends on the composition of the effluent, the extent of the exposure and the physical condition of the subject. Information relative to the effects on people can be extracted from physical and chemical characterization of the effluent (e.g. using ISO 13571:2007), from estimation of the toxic potency of fire...

Download Address

  • Download