BS 7899-2-1999 Code of practice for assessment of hazard to life and health from fire - Guidance on methods for the quantification of hazards to life and health and estimation of t.pdf

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1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 7899-2:1999 ICS 13.220

2、.01 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Code of practice for Assessment of hazard to life and health from fire Part 2: Guidance on methods for the quantification of hazards to life and health and estimation of time to incapacitation and death in firesThis British S

3、tandard, having been prepared under the direction of the Health and Environment Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 November 1999 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference F

4、SH/16 Draft for comment 98/540496 DC ISBN 0 580 28289 9 BS 7899-2:1999 Amendments issued since publication Amd. No. Date Comments Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee FSH/16, Hazards to life from fire, upon whi

5、ch the following bodies were represented: British Cable Makers Confederation British Electrical Systems Association (BEAMA Ltd.) British Nuclear Fuels plc British Plastics Federation British Railways Board British Rigid Urethane Foam Manufacturers Association British Rubber Manufacturers Association

6、 Ltd. British Telecommunications plc British Textile Technology Group Chemical Industries Association Chief and Assistant Chief Fire Officers Association Consumer Policy Committee of BSI Defence Evaluation and Research Agency Department of Health (NHS Estates) Department of the Environment Transport

7、 and the Regions (represented by the Building Research Establishment Ltd.) Department of Trade and Industry (Consumer Safety Unit, CA Division) Home Office International Wool Secretariat Loss Prevention Council Queen Mary and Westfield College RAPRA Technology Ltd. Warrington Fire Research CentreBS

8、7899-2:1999 BSI 11-1999 i Contents Page Committees responsible Inside front cover Foreword ii Introduction 1 1 Scope 1 2 Terms and definitions 1 3 Methods available and hazards to be assessed 3 4 Options and reliability of methods for determining hazard to life 4 5 Toxic hazard assessment method usi

9、ng time-concentration curves for full scale fires: designed to estimate time to incapacitation for exposed humans 7 6 The use of small-scale test data for estimating toxic potency and toxic hazard 16 7 Application of toxic potency and toxic hazard calculation methods 23 Annex A (informative) Sensory

10、 irritancy 24 Bibliography 25 Figure 1 Percentage frequency distribution of non-fire CO deaths 8 Figure 2 Hazard analysis for a furniture fire 14 Table 1 Comparison of the characteristics of hazard to life assessment method options 6 Table 2 Reported effects of smoke on visibility and behaviour 9 Ta

11、ble 3 Irritant concentrations of common fire gases 10 Table 4 Lethal exposure doses of irritants contributing to asphyxia and lung damage 11 Table 5 Simplified look up table for solutions to individual toxic gas FED equations for incapacitating exposure doses over a 1 min exposure time 12 Table 6 Li

12、miting conditions for tenability caused by heat 13 Table 7 Lift threat analysis for the first six minutes of a furniture fire 15 Table 8 Revised classification of fire types 18 Table 9 Currently accepted 30 min LC 50 concentrations for common fire gases 20 Table 10 Toxic potency analysis of material

13、s decomposed under non-flaming oxidative conditions in the NBS cup furnace 20 Table 11 Toxic potency analysis of materials decomposed under early, well ventilated flaming conditions in the NBS cup furnace 21 Table 12 Toxic potency analysis of materials decomposed less efficiently under early, well v

14、entilated flaming conditions in the NBS cup furnace 21 Table 13 Approximate lethal exposure doses (LCt 50 gm 23 min), and lethal concentrations (LC 50 gm 23 ) for common materials under different fire conditions 23 Table A.1 Mass loss concentrations of thermal decomposition products predicted to be

15、painfully irritant (mouse RD 50 gm 23 )2 4ii BSI 11-1999 BS 7899-2:1999 Foreword This part of BS 7899 has been prepared by Technical Committee FSH/16. It has been developed from DD 180:1989 Guide for the assessment of toxic hazards in fire in buildings and transport. This part of BS 7899, together w

16、ith parts 1 and 3, supersedes DD 180, which will be withdrawn when BS 7899-3 is published. The major hazards to life and health from fires are exposure to toxic fire effluents and heat. Exposure to these hazards, together with visual obscuration by smoke, also affect the ability of people to escape

17、from fires. Existing prescriptive safety regulations and codes contribute to the control of life threat in fires, but despite their influence there was an increasing incidence of death and injury from fires during the 1960s, 1970s and 1980s, particularly in relation to death and injury resulting fro

18、m exposure to toxic smoke. In addition to the current unacceptable incidence of death and injury from fire, a further problem is that the existing prescriptive control methods such as those given in the Building Regulations are inadequate for control of modern systems, as well as providing a potenti

19、al restriction on useful novel developments. There is therefore a great need for the development of effective methods for the assessement of life threat in fire and its regulation, based upon sound fire safety engineering principles. Major advances have been made in recent years in the development o

20、f fire engineering tests and calculation methods for the prediction of fire behaviour, and for the prediction of hazards to life and health from exposure to fire effluents. A basis now exists for making evaluations of the hazards to life in fires, and BSI is currently participating in work on the de

21、velopment of test and evaluation methods being developed in the UK, in the EU generally and in the International Organization for Standardization (ISO). This methodology is not yet completely available, but questions of hazards to life and health from fires still have to be faced. BS 7899 provides t

22、he best advice currently available for the assessment of hazard to life and health from fires, although further developments are expected in the future. In order to provide guidance on how these processes can be assessed, BS 7899 is written in a number of parts. BSI 11-1999 iii BS 7899-2:1999 Part 1

23、 General guidance. Part 1 provides an outline guide to the factors which should be considered when assessing the hazards to life and health presented by fires in structures (e.g buildings and transport). .At appropriate points it calls up documents in the series, which provide specific practical gui

24、dance on how the various elements of the hazard assessment can be performed. Part 2 Guidance on methods for the quantification of hazards to life and health and estimation of time to incapacitation and death in fires. This part of BS 7899 provides detailed guidance on methods for the quantification

25、of hazards to life and health and for the estimation of time to incapacitation and death in fires. It also includes methods for the estimation of lethal toxic potency from a chemical analysis of small-scale thermal decomposition test atmospheres. Part 3 Worked examples illustrating hazard assessment

26、s of various types. This part is in preparation. Other documents may be added in future to cover different aspects of the subject. It has been assumed in the preparation of this standard that the execution of its provisions will be entrusted to appropriately experienced or informed people for whose

27、guidance it has been prepared. Annex A is informative. As a code of practice, this British Standard takes the form of guidance and recommendations. It should not be quoted as if it were a specification and particular care should be taken to ensure that claims of compliance are not misleading. A Brit

28、ish Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a fron

29、t cover, an inside front cover, pages i to iv, pages 1 to 26, an inside back cover and a back cover. The BSI copyright notice displayed throughout this document indicates when the document was last issued.iv blank BSI 11-1999 1 BS 7899-2:1999 Introduction BS 7899 has been designed to provide a code

30、of practice to be followed when assessing hazards to life and health for potential fire scenarios. Part 1 of this code of practice (BS 7899-1) describes the many factors that can influence the threat to life and health from fires. It recommends a stepwise approach to a hazard assessment, by means of

31、 which the various factors can be considered. A key step in this process (step 4) is the quantification of hazardous effects from a fire and the estimation of time to incapacitation and death. This step takes as input the time-concentration or time-intensity curves of the life threatening components

32、 of fire effluent at the breathing zone of an exposed person and performs calculations to enable estimates to be made of the hazardous effects at different times during an exposure. This part of BS 7899 contains calculation methods which can be used for estimating the effects of exposure to the majo

33、r hazardous components of fire effluent: a) asphyxiant and irritant gases; b) smoke (obscuration); c) convected and radiant heat. The methods described in this part of BS 7899 are designed to be applied to a variety of fire scenarios using a variety of types of input data. A relatively simple scenar

34、io might involve an assessment of the developing hazard arising from the slow thermal decomposition of a small object made of a single material in a closed room, using input data obtained from a full scale test. A more complex scenario might involve an assessment of potential hazards to life from a

35、range of possible fires at the design stage of a large multi-compartment building. In order to complete this assessment, a wide range of factors would need to be considered and a variety of fire engineering calculations would be necessary, all of which are beyond the scope of this part of BS 7899. H

36、owever, at some point in such an analysis, consideration would have to be given to the effects on people of exposure to estimated fire effluents. The methods presented in this part of BS 7899 are intended to be directly applicable to such an estimation. A number of different methods can be used for

37、the estimation of toxic hazards from fires and several different approaches are described in this part of BS 7899. The methods described include: the application of time-concentration curves for individual toxic gases, obtained from large-scale fire tests or from fire modelling, for estimation of ti

38、me to incapacitation or death using physiological calculation methods for humans; the application of toxic potency data derived from small-scale combustion toxicity tests to toxic hazard assessment for full scale fires; the estimation of lethal toxic potency from a chemical analysis of small-scale c

39、ombustion toxicity test atmospheres (for use in method 2). 1 Scope This part of BS 7899 provides guidance for fire safety practitioners on methods for the quantification of hazards to life and health. It includes methods for the calculation of fire effluent toxicity, smoke obscuration and thermal co

40、mponents of fire hazard analysis for estimation of time to incapacitation and death in fire. Also included are methods for the estimation of lethal toxic potency from a chemical analysis of small-scale combustion toxicity test atmospheres and for the application of such data to toxic hazard assessme

41、nts for fires. 2 Terms and definitions For the purposes of this part of BS 7899 the following terms and definitions apply. 2.1 approximate lethal dose (ALD) estimate of the LCt 50 2.2 asphyxiant substance which may cause loss of consciousness or death by depriving the brain tissues of oxygen 2.3 com

42、bustion toxicity capacity of a substance within an effluent to cause injury to a living organism NOTE This definition is based on an ISO Guide 52 definition and PD 6503-1. 2.4 escape impairment effect of exposure to fire effluent and/or heat whereby escape capability is significantly reduced NOTE Th

43、is may be due to fire effluent or heat inhibiting occupants from entering affected areas or by reducing the efficiency or speed of escape in affected areas. 2.5 exposure dose potential dose of a toxicant available by inhalation expressed as the exposure concentration multiplied by the exposure time

44、2.6 fire effluent total gaseous, volatile and particulate (liquid or solid) products from combustion or pyrolysis 2.7 fire hazard physical situation with a potential for harm to life or limb, or damage to property, or both, from the effect of fire (see BS 6336) 2.8 fire scenario generalized descript

45、ion of an actual or hypothetical fire incident2 BSI 11-1999 BS 7899-2:1999 2.9 fractional effective concentration (of smoke) (FEC) concentration of smoke present in a fire at any time divided by the concentration considered to significantly affect escape efficiency 2.10 fractional effective dose (FE

46、D) average exposure dose of one or more toxic effluents present in a fire over a defined period of time divided by the exposure dose required to obtain a defined toxic endpoint (escape impairment, incapacitation or death) 2.11 fractional irritant concentration (FIC) concentration of one or more irri

47、tant effluents present in a fire at any time divided by the exposure concentration required to obtain a defined toxic endpoint (escape impairment, incapacitation or death) 2.12 fractional lethal dose (FLD) average exposure dose of one or more toxic effluents present in a fire over a defined period o

48、f time divided by the lethal exposure dose 2.13 irritant substance which can cause discomfort, pain or tissue damage to the mucous membranes of the eyes, nose, throat and lungs, which can lead to a degree of incapacitation or death 2.14 LC 50 (lethal concentration, 50 %) concentration of a toxic gas

49、 or fire effluent statistically calculated to cause the deaths of 50 % of test animals exposed for a specified time NOTE 1 The LC 50 is expressed as ppm for a toxic gas and in gm 23 for a fire effluent. NOTE 2 When comparing LC 50 data, both the exposure duration and the post-exposure period over which the deaths were scored need to be taken into account. 2.15 LCt 50 (lethal exposure dose) product of LC 50 and the exposure duration over which it was determined NOTE The LCt 50 is expressed as ppmmin for a toxic gas and in gm 23 mi