1、BRITISH STANDARD BS 7990:2003 Tube furnace method for the determination of toxic product yields in fire effluents ICS 13.220.99 BS 7990:2003 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 19 March 2003 BSI 19 March 2003 The following BSI ref
2、erences relate to the work on this British Standard: Committee reference FSH/16 Draft for comment 00/541663 DC ISBN 0 580 41240 7 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
3、ch the following bodies were represented: BRE FRS BRE/LPC Laboratories British Cables Association British Electrical Systems Association (BEAMA Ltd.) British Nuclear Fuels plc. British Plastics Federation British Rigid Urethane Foam Manufacturers Association British Rubber Manufacturers Association
4、Ltd. 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) EURISOL UK Mineral Wool Association Fibre Cement Manufacturers Associat
5、ion Limited Ministry of Defence UK Defence Standardization Office of the Deputy Prime Minister Building Regulations Division Office of the Deputy Prime Minister (represented by the Building Research Establishment) Queen Mary and Westfield College RAPRA Technology Ltd. Royal Society of Chemistry Warr
6、ington Fire Research Centre Co-opted members Amendments issued since publication Amd. No. Date CommentsBS 7990:2003 BSI 19 March 2003 i Contents Page Committees responsible Inside front cover Foreword ii Introduction 1 1S c o p e 2 2 Normative references 2 3T e r m s a n d d e f i n i t i o n s 2 4
7、Principle 3 5A p p a r a t u s 4 6 Air supplies 9 7 Establishment of furnace temperature profile and setting of furnace temperature 9 8 Test specimen preparation 10 9 Test decomposition conditions 11 10 Procedure 12 11 Calculations 14 12 Test report 17 Annex A (informative) Guidance on choice of add
8、itional decomposition conditions 18 Annex B (informative) Guidance on calculation of lethal toxic potency of combustion products 19 Annex C (informative) Guidance on application of data from the tube furnace test to assessment of toxic hazard in fires 21 Annex D (informative) Guidance on application
9、 of data from the tube furnace test to health and safety assessments of combustion products 21 Annex E (informative) Guidance on application of data from the tube furnace test to assessment of environmental hazards from combustion products from fires 22 Bibliography 23 Figure 1 Tube furnace decomp o
10、sition and sampling apparatus 6 Figure 2 Dimensions of a suitable quartz furnace tube and test specimen boat 7 Figure 3 Dimensions of mixing and measurement chamber 8 Table 1 Values of ( M/V m )1 6BS 7990:2003 ii BSI 19 March 2003 Foreword This British Standard has been prepared by Technical Committ
11、ee FSH/16. It describes a tube furnace method for the determination of toxic product yields in fire effluents. It has been developed for use in conjunction with BS 7899-1 and BS 7899-2, to provide data on toxic product concentrations and yields in fire effluents from materials and products decompose
12、d under a range of fire conditions. These data are suitable for use in the assessment of toxic and environmental hazards and risks to life and health from fires. One of the prerequisites for the application of BS 7899 is information on toxic product yields for estimation of the toxic potency and tox
13、ic hazards of fire effluents. There are a number of ways in which this information can be obtained and applied, as described in BS 7899-1 and BS 7899-2. One method involves the decomposition of materials or products in a small-scale test apparatus under conditions occurring in different types and st
14、ages of full-scale fires. Measurements of toxic product concentrations in the test enable calculations to be made of toxic product yields, and overall toxic potencies, to be expected during relevant types and stages of full-scale fires. These data can then be used in conjunction with other data (inc
15、luding ignitability and fire growth data) and suitable calculation methods, for the assessment of toxic hazard in full-scale fire scenarios. This standard gives a method for such a small-scale test. Although there are no statutory requirements placing limits on the toxicity of fire effluent from mat
16、erials and products used in buildings and transport, toxicity test data are often included in specifications. Manufacturers, suppliers, specifiers and regulators of products are often faced with the need to generate and apply data from small-scale toxic potency tests. A requirement for the applicati
17、on of data from small-scale toxic potency tests is that the combustion conditions and data produced have to be related to those in a range of stages of full-scale fires. The method described in this standard has been developed specifically to meet these requirements. It is also extremely important t
18、o recognize that toxic potency is only one element in the development of toxic hazard, which is often more dependent on ignitability and fire growth characteristics of materials and products. It has been assumed in the preparation of this standard that the execution of its provisions will be entrust
19、ed to appropriately qualified and competent people for whose use it has been produced. WARNING. This British Standard calls for the use of substances and/or procedures that may be injurious to health if adequate precautions are not taken. It refers only to technical suitability and does not absolve
20、the user from legal obligations relating to health and safety at any stage. In particular, attention is drawn to the following hazards. a) The test procedure involves combustion processes, and the combustion products can give rise to fire hazards. To avoid accidental leakage of hazardous combustion
21、products the entire test system should be placed in a fume cupboard with an external venting system. b) The venting system should be checked for proper operation before testing and should discharge into an exhaust system with adequate capacity. c) As, in unfavourable circumstances, extremely rapid c
22、ombustion or explosion can occur when the device is in operation, a protective screen between the operator and the tube furnace is recommended and, in addition, care should be taken to ensure that the gas outlet at the end of the furnace tube is as large a diameter as possible.BS 7990:2003 BSI 19 Ma
23、rch 2003 iii This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises of a front c
24、over, an inside front cover, pages i to iv, pages 1 to 23 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued.iv blankBS 7990:2003 BSI 19 March 2003 1 Introduction For any specific material or product the effluent yields in fires depend u
25、pon the thermal decomposition conditions. The most important variables are whether the decomposition is non-flaming or flaming, and for flaming decomposition the fuel/oxygen ratio. Based upon these variables it is possible to classify fires into a number of types, as detailed in BS 7899-2:1999, Tabl
26、e 8. For non-flaming oxidative pyrolysis from externally applied radiation, (BS 7899-2:1999, Table 8 fire type 1b) it is sufficient to heat a specimen of the test material in air. The yields of thermal decomposition products then depend upon the specimen temperature above a minimum at which little o
27、r no thermal decomposition occurs up to a maximum above which flaming ignition is likely to occur. Although it is therefore possible to measure effluent yields over a wide range of temperatures it is considered reasonable to specify a fixed temperature for this standard at which the majority of mate
28、rials will evolve thermal decomposition products, but at an insufficient rate for flaming ignition to occur. The air supply should be sufficient to maintain an oxidative environment in contact with the specimen, but not so much as to encourage glowing combustion. For flaming decomposition the produc
29、t yields have been shown to be highly dependent upon the fuel/oxygen ratio, such that the yields of important toxic products such as carbon monoxide can vary by up to a factor of 50 between well ventilated and vitiated conditions (see references 1 to 5). It is therefore considered vital that for a s
30、tandard test method the fuel/oxygen ratio should be controlled. The fuel/oxygen ratio can be expressed in terms of the equivalence ratio ( ), the fuel mass to oxygen mass ratio in the test divided by the stoichiometric fuel mass to oxygen mass ratio. The value of can be calculated as follows: = (F t
31、 /O t ) (O s /F s ) where In practice it has been found that for well ventilated conditions, product yields are relatively constant at equivalence ratios with values of 1.BS 7990:2003 2 BSI 19 March 2003 1 Scope This British Standard describes a tube furnace method for the generation of fire effluen
32、t for the identification and measurement of its constituent combustion products. It uses a moving test specimen and a tube furnace at different temperatures and air flow rates as the fire model. The method can be used to model a wide range of fire conditions by using different combinations of temper
33、ature, non-flaming and flaming decomposition conditions and different fuel/oxygen ratios in the tube furnace. These include the following types of fires, as detailed in BS 7899-2:1999, Table 8: Stage 1: Non-flaming: Stage 1b) Oxidative pyrolysis from externally applied radiation; Stage 2: Well venti
34、lated flaming (representing a flaming developing fire); Stage 3: Less well ventilated flaming: Stage 3a) Small vitiated fires in closed or poorly ventilated compartments; Stage 3b) Post-flashover fires in large or open compartments. For each flaming fire type the minimum conditions of test are speci
35、fied in terms of the equivalence ratio as follows: Stage 2: 0.75; Stages 3a) and 3b) =20. 2 . NOTE 1 Guidance on choice of additional decomposition conditions is given in Annex A. The test method described in this standard can be used solely to measure and describe the properties of materials, produ
36、cts or systems in response to heat or flame under controlled laboratory conditions. It is not suitable to be used by itself for describing or appraising the fire hazard of materials, products or systems under actual fire conditions or as the sole source on which regulations pertaining to toxicity ca
37、n be based. NOTE 2 Guidance on calculation of lethal toxic potency of combustion products is given in Annex B. NOTE 3 Guidance on the application of data from the tube furnace test to assessment of toxic hazard in fires, to health and safety assessments of combustion products and to environmental ha
38、zard assessment of combustion products is given in Annex C, Annex D and Annex E, respectively. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest ed
39、ition of the referenced document (including any amendments) applies. BS 7899-2:1999, 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 fires. 3
40、Terms and definitions For the purposes of this British Standard the terms and definitions given in BS 7899-2 and the following apply. 3.1 combustible load mass of the components of a test specimen capable of combustion in the furnace NOTE This usually includes all components of a specimen excluding
41、inert fillers and other non-combustible components such as metal frames. 3.2 equivalence ratio fuel mass to oxygen mass ratio in the test divided by the stoichiometric fuel mass to oxygen mass ratio NOTE For the tube furnace method this is the mass loss rate of combustible effluent from the test spe
42、cimen in milligrams per minute (mg min 1 ) divided by the mass flow rate of oxygen in the primary air introduced into the furnace in milligrams per minute (mg min 1 ) divided by the stoichiometric fuel mass to oxygen mass ratio for the material under test.BS 7990:2003 BSI 19 March 2003 3 3.3 mass ch
43、arge concentration concentration of fire effluents from a material defined in terms of the mass of material exposed to burning conditions (mass charge) and the volume into which the effluent is dispersed, expressed in g m 3BS 7899-2:1999, definition 2.19 3.4 mass loss concentration concentration of
44、fire effluents from a material defined in terms of the mass of material decomposed (mass loss) and the volume into which the effluent is dispersed, expressed in g m 3BS 7899-2:1999, definition 2.21 3.5 mass loss exposure dose mass loss concentration multiplied by the exposure time, expressed in g m
45、3 min BS 7899-2:1999, definition 2.22 3.6 yield mass of an effluent component divided by the mass loss of the test specimen associated with the production of that mass of the effluent component 3.7 volume yield volume of an effluent component at standard temperature and pressure (20 C and 101.325 kP
46、a) divided by the mass loss of the test specimen associated with the production of that volume of the effluent component 4 Principle A test specimen, in granular or rod form, is placed in a clear heat resistant quartz boat, and introduced at a constant rate along a clear quartz furnace tube through
47、the hot zone of a fixed tubular furnace. A stream of primary air is passed through the quartz furnace tube and over the test specimen to support combustion. The fire effluent is expelled from the quartz furnace tube into a mixing and measuring chamber, where it is diluted with secondary air to a nom
48、inal total air flow rate of (50 1) l min 1through the chamber and then exhausted to waste. Samples of the effluent mixture are taken from the chamber for analysis. The decomposition conditions in the furnace are set using different combinations of temperature and primary air flow rate in separate te
49、st runs, to model the decomposition condition in a range of fire stages as characterized in BS 7899-2. For flaming decomposition conditions, different fuel/oxygen ratios and hence different equivalence ratios, are obtained when different primary air flow rates are used in relation to the constant rate of introduction of the fuel. The aim in each test run is (after an initial settling down period when decomposition conditions and p
