ASTM E1678-2008b Standard Test Method for Measuring Smoke Toxicity for Use in Fire Hazard Analysis.pdf

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1、Designation: E 1678 08bAn American National StandardStandard Test Method forMeasuring Smoke Toxicity for Use in Fire Hazard Analysis1This standard is issued under the fixed designation E 1678; the number immediately following the designation indicates the year oforiginal adoption or, in the case of

2、revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONThe pyrolysis or combustion of every combustible material or product produces smoke that is toxi

3、c.It is, therefore, desirable to establish a test method for the development of data characterizing smoketoxicity as an element of fire hazard analyses for both pre-flashover and post-flashover fires. The testmethod includes quantification of the toxicity of the smoke and ascertain whether the obser

4、ved toxicitycan be attributed to the major common toxicants.1. Scope1.1 This fire-test-response standard covers a means fordetermining the lethal toxic potency of smoke produced froma material or product ignited while exposed to a radiant heatflux of 50 kW/m2for 15 min.1.2 This test method is limite

5、d to test specimens no largerthan 76 by 127 mm (3 by 5 in.), with a thickness no greaterthan 51 mm (2 in.). Specimens are intended to be representa-tive of finished materials or products, including composite andcombination systems.1.3 Lethal toxic potency values associated with 30-minexposures are p

6、redicted using calculations that use combustionatmosphere analytical data for carbon monoxide, carbon diox-ide, oxygen (vitiation) and, if present, hydrogen cyanide,hydrogen chloride, and hydrogen bromide. The predictiveequations are therefore limited to those materials and productswhose smoke toxic

7、ity can be attributed to these toxicants. Ananimal check determines the extent to which additional toxi-cants contribute to the lethal toxic potency of the smoke.1.4 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.5 This stan

8、dard measures and describes the response ofmaterials, products, or assemblies in response to heat undercontrolled conditions, but does not by itself incorporate allfactors required for fire hazard of fire risk assessment of thematerials, products, or assemblies under actual fire conditions.1.6 This

9、standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations (particularly with regard to thecare

10、and use of experimental animals) prior to use. For specifichazards statements, see Section 7 and Note X1.1.2. Referenced Documents2.1 ASTM Standards:2E 176 Terminology of Fire StandardsE 800 Guide for Measurement of Gases Present or Gener-ated During Fires2.2 ISO Document:TR 9122 (Parts 15) Toxicity

11、 Testing of Fire Effluents33. Terminology3.1 DefinitionsFor definitions of general terms used inthis test method, refer to Terminology E 176.3.2 Definitions of Terms Specific to This Standard:3.2.1 carboxyhemoglobin saturation, nthe percent ofblood hemoglobin predominately converted to carboxyhemo-g

12、lobin from reaction with inhaled carbon monoxide.3.2.1.1 DiscussionThe chemical reaction between carbonmonoxide and hemoglobin in blood is reversible. The effect ofcarbon monoxide on the exposed person may not be reversible.3.2.2 concentration-time curve, na plot of the concentra-tion of a gaseous t

13、oxicant as a function of time.3.2.2.1 DiscussionThe concentration-time curve can alsobe used to represent the sum total of all combustion productsinstead of just a single one.3.2.3 Ct product, nthe concentration-time product in (L/L)min obtained by integration of the area under aconcentration-time c

14、urve.1This test method is under the jurisdiction of ASTM Committee E05 on FireStandards and is the direct responsibility of Subcommittee E05.21 on Smoke andCombustion Products.Current edition approved Dec. 15, 2008. Published January 2009. Originallyapproved in 1995. Last previous edition approved i

15、n 2008 as E 1678 08a.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standa

16、rds Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.3.1 DiscussionValues expressed using this unit arenumerically equal to those using the previous

17、ly cited unit, ppm,a term whose use is discouraged.3.2.4 fractional exposure dose (FED), nthe ratio of theintegrated area under the concentration-time curve for agaseous toxicant or the sum of all combustion productsproduced in a given test to that integrated C(t) area which hasbeen determined stati

18、stically from independent experimentaldata to produce lethality in 50 % of test animals within aspecified exposure and postexposure time.3.2.4.1 DiscussionWhen C is nearly constant over time,the time values in this ratio numerically cancel, and the FED issimply the ratio of the average concentration

19、 of a gaseoustoxicant to its LC50value for the same exposure time. Whenonly a single measurement of C is made during a test, theaccuracy of this simplification is not known. When not usedwith reference to a specific toxicant, the term FED representsthe summation of FEDs for individual toxicants in a

20、 combus-tion atmosphere.3.2.5 LC50, na measure of lethal toxic potency; theconcentration of gas or smoke calculated statistically fromconcentration-response data to produce lethality in 50 % of testanimals within a specified exposure and postexposure time,expressed in L/L.3.2.5.1 DiscussionValues ex

21、pressed using this unit arenumerically equal to those using the previously cited unit, ppm,a term whose use is discouraged.3.2.6 mass loss concentration, nthe mass loss of a testspecimen per unit exposure chamber volume in gm3.3.2.7 post-flashover, n and adjreferring to the state of afire after flas

22、hover.4. Summary of Test Method4.1 In this test method, a test specimen is subjected toignition while it is exposed for 15 min to a radiant heat flux of50 kW/m2. (See X1.2.2.) The smoke produced is collected for30 min within a 200-L chamber communicating with thecombustion assembly through a connect

23、ing chimney. Concen-trations of the major gaseous toxicants are monitored over the30-min period, with Ct products for each being determinedfrom integration of the areas under the respectiveconcentration-time plots. The Ct product data, along with themass loss of the test specimen during the test, ar

24、e then used incalculations to predict the 30-min LC50of the test specimen.4.2 The predicted LC50is then confirmed in comparabletests by exposing six rats, restrained for head-only exposure,for 30 min to the smoke produced from that mass of the testspecimen whose mass loss concentration during the 30

25、-minperiod is approximately (610 %) equivalent to 70 % and to130 % of its estimated LC50. If no more than one rat diesduring the 30-min exposure, or within 14-days postexposure tothe mass loss concentration corresponding to 70 % of the LC50,and at least five rats die during the 30-min exposure, or w

26、ithin14-days postexposure to the mass loss concentration corre-sponding to 130 % of the LC50, the predicted LC50is consid-ered to be confirmed. Confirmation ensures that the monitoredtoxicants account for the observed toxic effects.4.3 An animal test result that does not confirm the predic-tion indi

27、cates the presence of one or more additional toxicantsor toxicological antagonists, and the degree of disagreementindicates the importance of the unmeasured factors.4.4 For calculation of hazard from pre-flashover, flamingfires, the toxicant gas yields and LC50values are to be used asexperimentally

28、determined. For calculation of hazard frompost-flashover fires, the yields of carbon monoxide are aug-mented to reflect the higher yields produced in such fires. Theexperimental LC50values are then adjusted using a specifiedcalculation to produce LC50(post-flashover) values.5. Significance and Use5.

29、1 This test method has been designed to provide data forthe mathematical modeling of fire hazard as a means for theevaluation of materials and products and to assist in theirresearch and development.5.2 This test method is used to predict, and subsequentlyconfirm, the lethal toxic potency of smoke p

30、roduced upon theexposure of a material or product to specific fire test condi-tions. Confirmation determines whether certain major gaseoustoxicants account for the observed toxic effects and lethal toxicpotency. If a predicted lethal toxic potency value is notconfirmed adequately, indicating a poten

31、tial for unusual orunexplained toxicity, the lethal toxic potency will need to beinvestigated using other methodology, such as conducting anexperimental determination of the LC50using the apparatusdescribed. (See X1.3.1 and X1.3.2.)5.3 This test method produces lethal toxic potency valuesthat are ap

32、propriate for use in the modeling of both pre-flashover and post-flashover fires. Most fire deaths due tosmoke inhalation in the U.S. occur in areas other than the roomof fire origin and are caused by fires that have proceededbeyond the room of fire origin. It is assumed that these areflashover fire

33、s. Therefore, the principal emphasis is placed onevaluating toxic hazard under these conditions. In post-flashover fires, large concentrations of carbon monoxide resultsfrom reduced air supply to the fire plume and other room-scalefactors. Bench-scale tests do not have the capacity to simulatethese

34、phenomena. The lethal toxic potency values determinedin this test method are obtained from fuel/air ratios morerepresentative of pre-flashover, rather than post-flashover con-ditions. In cases where a pre-flashover fire representation isdesired in fire hazard modeling, these LC50values are appro-pri

35、ate. Lethal toxic potency and carbon monoxide yield valuesdetermined in this test method require adjustment for use inmodeling of the hazard from post-flashover conditions. (SeeX1.4.1.)5.4 The lethal toxic potency values determined in this testmethod have a level of uncertainty in their accuracy whe

36、n usedto predict real-scale toxic potencies. (See X1.4.2.)5.4.1 The accuracy of the bench-scale data for pre-flashoverfires has not been established experimentally. The combustionconditions in the apparatus are quite similar to real pre-flashover fires, although the mass burning rate may be higher a

37、tthe 50 kW/m2irradiance of the test method.5.4.2 Comparison of the toxicant yields and LC50(post-flashover) values obtained using this method have been shownin limited tests (22) to reproduce the LC50values fromreal-scale, post-flashover fires to within an accuracy of ap-proximately a factor of thre

38、e. Therefore, LC50(post-flashover)E 1678 08b2values differing by less than a factor of three are indistinguish-able from each other. (See X1.4.2.)5.5 This test method does not attempt to address thetoxicological significance of changes in particulate and aerosolsize, smoke transport, distribution, o

39、r deposition or changes inthe concentration of any smoke constituent as a function oftime as may occur in a real fire.5.6 The propensity for smoke from any material to have thesame effects on humans in fire situations can be inferred onlyto the extent that the rat is correlated with humans as abiolo

40、gical system. (See X1.2.5.)5.7 This test method does not assess incapacitation. Inca-pacitation must be inferred from lethal toxic potency values.5.8 The effects of sensory irritation are not addressed by thistest method.6. Apparatus6.1 Animal Exposure ChamberShown in Figs. 1 and 2,atransparent poly

41、carbonate or polymethylmethacrylate chamberwith a nominal volume of 0.2 m3(200 L). (See X1.2.6.) Itsinside dimensions are 1220 by 370 by 450 mm (48 by 1412 by1734 in.). The six animal ports, intended for head-only expo-sure, are located in a horizontal row, approximately half wayfrom the bottom to t

42、he top of the chamber, in the front wall. Aplastic bag with an approximate volume of 0.05 m3(50 L orapproximately 13 gal) is attached to the port at the end of thechamber during a test to provide for gas expansion. Theexposure box is equipped with a gas sampling port at theanimal nose level in the g

43、eometric center of the exposurechamber and with a port for returning gases in the end wallclosest to the gas analyzers. A thermocouple shall be providedto monitor the temperature at the level of the animal ports.There are two doors in the exposure chamber, in the front wallnear the connection to the

44、 combustion cell and in the end wallnearest the animal ports. The purpose of the doors is to allowfor cleaning and maintenance of the chamber, chimney, andsmoke shutter and to provide fresh air during calibration of theheat lamps and immediately prior to testing.6.2 Smoke Shutter, made of stainless

45、steel plate and situatedinside the animal exposure chamber. It is positioned so that itwill close over the chimney opening. It is hinged and providedwith a positive locking mechanism. The purpose of the shutteris to seal the combustion chamber and chimney from theexposure chamber at the end of irrad

46、iation. A wire attached tothe shutter and a simple push rod are provided for gentleclosing of the shutter. A wire attached to a clamp locks theshutter in place. To produce a gas-tight seal, the underside ofthe shutter is covered with a 12-mm (0.5-in.) thick blanket oflow-density ceramic fiber insula

47、tion (approximately 65 kg/m3),which is further covered with stainless steel foil.6.3 Chimney (Fig. 3)A stainless steel assembly approxi-mately 30 by 300 mm (114 by 1134 in.), inside dimensions, and300 mm (1134 in.) wide. It connects the combustion cell to theanimal exposure chamber. The chimney is d

48、ivided into threechannels by stainless steel dividers. The center channel isapproximately 150 mm (6 in.) wide. The purpose of thedividers is to induce smoke to travel up through the centerportion of the chimney, while air from the animal exposurechamber is drawn down through the outside channels top

49、rovide air to the combustion cell. The chimney is connected tothe underside of the animal exposure chamber by clamps,permitting its removal for cleaning. It is sealed to the animalchamber by low-density ceramic fiber insulation (approxi-mately 65 kg/m3). The other end of the chimney is sealed to thecombustion cell by an H-shaped trough with a small quantity ofthe same fiber insulation in the trough.6.4 Combustion CellShown in Figs. 4-6, a horizontalquartz tube with a 127-mm (5-in.) inside diameter and approxi-mately 320 mm (1212 in.) long. It is sealed a