ASTM E1623-2004 Standard Test Method for Determination of Fire and Thermal Parameters of Materials Products and Systems Using an Intermediate Scale Calorimeter (ICAL)《使用中等规模量热计(ICA.pdf

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1、Designation: E 1623 04An American National StandardStandard Test Method forDetermination of Fire and Thermal Parameters of Materials,Products, and Systems Using an Intermediate ScaleCalorimeter (ICAL)1This standard is issued under the fixed designation E 1623; the number immediately following the de

2、signation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This fire-test-response sta

3、ndard assesses the response ofmaterials, products, and assemblies to controlled levels ofradiant heat exposure with or without an external ignitor.1.2 The fire-test-response characteristics determined by thistest method include the ignitability, heat release rates, massloss rates, visible smoke deve

4、lopment, and gas release ofmaterials, products, and assemblies under well ventilatedconditions.1.3 This test method is also suitable for determining manyof the parameters or values needed as input for computer firemodels. Examples of these values include effective heat ofcombustion, surface temperat

5、ure, ignition temperature, andemissivity.1.4 This test method is also intended to provide informationabout other fire parameters such as thermal conductivity,specific heat, radiative and convective heat transfer coeffi-cients, flame radiation factor, air entrainment rates, flametemperatures, minimum

6、 surface temperatures for upward anddownward flame spread, heat of gasification, nondimensionalheat of gasification (1)2and the F flame spread parameter (seeTest Method E 1321). While some studies have indicated thatthis test method is suitable for determining these fire param-eters, insufficient te

7、sting and research have been done to justifyinclusion of the corresponding testing and calculating proce-dures.1.5 The heat release rate is determined by the principle ofoxygen consumption calorimetry, via measurement of theoxygen consumption as determined by the oxygen concentra-tion and flow rate

8、in the exhaust product stream (exhaust duct).The procedure is specified in 11.1. Smoke development isquantified by measuring the obscuration of light by thecombustion product stream (exhaust duct).1.6 Specimens are exposed to a constant heating flux in therange of 0 to 50 kW/m2in a vertical orientat

9、ion. Hot wires areused to ignite the combustible vapors from the specimen duringthe ignition and heat release tests. The assessment of theparameters associated with flame spread requires the use of lineburners instead of hot wire ignitors.1.6.1 Heat release measurements at low heat flux levels (25 m

10、 in size.A2.2.7 A refrigerated column is the most successful ap-proach to cool and dry the gases. Provide a drain plug toremove the collected water from time to time. Alternativedevices are also acceptable.A2.2.8 If carbon dioxide is to be removed, use carbondioxide removal media, as indicated in Fi

11、g. 6.A2.3 Combustion Gas AnalysisA2.3.1 Oxygen ConcentrationUse an oxygen analyzer,meeting the specifications under 6.4.9.2, preferably of theparamagnetic type.A2.3.2 Carbon Monoxide and Dioxide ConcentrationAnalyzers found suitable are nondispersive infrared analyzers.See Guide E 800.A2.3.3 Other C

12、ombustion GasesUse Guide E 800 fordetails of suitable analyzers when the concentrations of othercombustion gases, such as water, total hydrocarbon, nitrogenoxide, hydrogen cyanide, or hydrogen chloride, are to bemeasured, for special purposes.A2.3.4 Time Shift Gas concentration measurements re-quire

13、 the use of appropriate time shifts in order to account forgas transit time within the sampling system.A2.4 Smoke ObscurationA2.4.1 White Light System:A2.4.1.1 One suitable light measuring system based onwhite light has the following components: a lamp, planoconvex lenses, an aperture, a photocell,

14、and an appropriatepower supply. Mount lenses, lamp, and photocell inside twohousings, located on the exhaust duct, diametrically oppositeeach other. It has been found that a system consisting solely ofa white light and a photocell, along the exhaust duct, acrossfrom each other and at an angle to the

15、 vertical, is satisfactoryin some cases.A2.4.1.2 Use a lamp of the incandescent filament type,which operates at a color temperature of 2900 6 100 K. Supplythe lamp with stabilized direct current, stable within 60.2 %(including temperature, short term and long term stability).Center the resultant lig

16、ht beam on the photocell.A2.4.1.3 Select the lens system such that the lens L2,according to Fig. 7, has a diameter, d, chosen with regard to thefocal length, f,ofL2so that d/f $ 0.04.A2.4.1.4 Place the aperture in the focus of lens L2accordingto Fig. 7.A2.4.1.5 Use a detector with a spectrally distr

17、ibuted re-sponse according to the CIE photopic curve and linear within5 % over an output range of at least 3.5 decades. Check thislinearity over the entire range of the instrument periodicallywith calibrated optical filters.A2.4.1.6 The system described as follows is an example ofa light measuring s

18、ystem that has been found to be satisfactory:(1) lensesPlano convex: diameter 40 mm, focal length 50mm; (2) lampOsram Halo Stars, 64410, 6 V, 10 W, orequivalent; (3) photocellUnited Detector Technology, PINFIG. A2.3 Cross Type Sampling ProbeFIG. A2.4 Cross Type Gas Sampling ProbeE1623041510 AP, or e

19、quivalent; and (4)voltage supply Gresham LionLtd, Model G 3 012, or equivalent.A2.4.1.7 Design a system that is easily purged against sootdeposits. The use of holes in the periphery of the two housingsis a means of achieving this objective.A2.4.2 Laser System An acceptable alternate system formeasur

20、ements of smoke obscuration uses a laser beam. An 0.5to 2.0 mW helium-neon laser beam is projected across theexhaust duct. Couple the two halves of the device rigidlytogether (see Fig. 8).A3. CONSIDERATIONS FOR HEAT RELEASE MEASUREMENTSA3.1 Measurement of Rate of Heat Release by OxygenConsumptionA3.

21、1.1 IntroductionIn 1917, Thornton (2) showed that fora large number of organic fuels, a more or less constant netamount of heat is released per unit of oxygen consumed forcomplete combustion. Huggett (3) obtained an average valuefor this constant of 12.1 MJ/kg of O2. It is appropriate to usethis val

22、ue for practical applications; it is accurate, with veryfew exceptions, to within 6 5%.A3.1.2 Thorntons rule indicates that it is sufficient tomeasure the oxygen consumed in a combustion system in orderto determine the net heat released. This is particularly usefulfor full-scale fire test applicatio

23、ns. For example, for compart-ment fires, the oxygen consumption technique is much moreaccurate and easier to implement than methods based onmeasuring all the terms in a heat balance of the compartment.A3.1.3 Perhaps the first application of the O2consumptionprinciple in fire research was by Parker (

24、10) using Test MethodE84tunnel test. Later, Sensenig applied it to an intermediatescale room test (7). During the late seventies and early eighties,the O2consumption technique was refined at the NationalInstitute for Standards and Technology (NIST, formerly Na-tional Bureau of Standards). A paper by

25、 Parker (11) givesequations to calculate rate of heat release by O2consumptionfor various applications. The technique is now used extensivelyin many laboratories all over the world, both in bench-scale(12) and full-scale (Proposal P147 and (13) fire test applica-tions.A3.1.4 The objective of this se

26、ction is to provide a compre-hensive set of equations and guidelines to determine the rate ofheat release in ICAL fire tests based on the O2consumptionprinciple. The approach followed here is somewhat differentfrom Parker (11) as the emphasis is on intermediate-scale firetest applications and the us

27、e of volumetric flows is avoided.Volumetric flows require specification of temperature andpressure. Various investigators have used different combina-tions of reference pressure and temperature. This leads toconfusion, which is greatly minimized if mass flows are used.A3.1.5 The basic requirement is

28、 that all combustion prod-ucts be collected in a hood and removed through an exhaustduct. At a distance downstream of the hood sufficient foradequate mixing, both flow and composition of the combustiongases are measured. It is assumed here that it is not possible tomeasure the air flow into the syst

29、em, as this is generally thecase for full-scale fire tests. The differences in treatment andequations to be used are mainly due to the extent to whichcombustion gas analysis is made. At least O2shall be mea-sured. However, heat release rate measurements will be moreaccurate by measuring CO2and CO ad

30、ditionally.A3.1.6 It must be emphasized that the analysis is approxi-mate. The following list describes the main simplifying as-sumptions made:A3.1.6.1 The amount of energy released by complete com-bustion per unit of oxygen consumed is taken as: E = 12.1MJ/kg of O2.A3.1.6.2 All combustion gases are

31、 considered to behave asideal gases, in other words one mole of any gas is assumed tooccupy a constant volume at the same pressure and tempera-ture.A3.1.6.3 Incoming air consists of O2,CO2,H2O, and N2.All “inert” gases, which do not take part in the combustionreaction, are lumped into the nitrogen.A

32、3.1.6.4 O2,CO2, and CO are measured on a dry basis, inother words water vapor is removed from the specimen beforecombustion gas analysis measurements are made.A3.1.7 In the analysis to follow, initial emphasis will beplaced on the flow measurement. Equations to calculate floware applicable, unless o

33、therwise indicated, irrespective of theconfiguration of the combustion gas analysis system. In sub-sequent sections, distinction is made between various combus-tion gas analyzer combinations.A3.2 Flow MeasurementsA3.2.1 Mainly two techniques are used to measure massflow in the exhaust duct of ICAL f

34、ire tests.A3.2.2 The first technique measures mass flow by thepressure drop across, and temperature at, an orifice plate (seeEq A4.1). If the test is conducted within a narrow range ofconditions, the orifice plate coefficient, C, is approximatelyconstant. Determine the value of the orifice plate coe

35、fficientusing a gas burner calibration or an alternative method thatprovides equivalent results. However, if flows are variedduring a test or if temperature changes are considerable, theeffects on C of the Reynolds number and pressure at thedownstream side of the orifice plate must be taken intoacco

36、unt. Information on such corrections and on various designoptions (for example location of the pressure taps) are found inRef (14).A3.2.3 The other technique is to measure velocity at onepoint in the duct, usually along the center line. The flow is thencalculated using a predetermined shape of the v

37、elocity profilein the duct. The latter is obtained by measuring velocity at asufficient number of representative points over the diameter orcross section of the duct prior to any fire tests. Detailedprocedures to obtain this profile are described in (15). Usually,conditions in intermediate-scale fir

38、e tests are such that the flowE16230416in the duct is turbulent, resulting in a shape factor kc(equalsratio of the average velocity to the velocity along the center-line) close to 1.A3.2.4 Due to considerable soot production in many fires,pitot static tubes cannot be used because of the potential fo

39、rclogging of the holes. In order to deal with this problem, amore robust bidirectional probe was designed by McCaffreyand Heskestad (16). This involves measuring the differentialpressure across the probe and the centerline velocity (see EqA4.2), and is valid in the range of Reynolds numbers, Re: 403

40、800. In this case f (Re) is taken as a constant (1.08),which greatly simplifies the calculations. This equation (see EqA4.2) is preferred to Eq A4.1 for intermediate scale measure-ments of heat release rate. Further details of this and of allother calculations discussed in this annex are found in a

41、paperby Janssens (17). For additional details, see also ISO 9705.A3.3 Rate of Heat Release Measurement if Only Oxygenis MeasuredA3.3.1 In this case all water vapor and CO2are eliminatedby the use of appropriate filtering media. This leads to theassumption that the specimen combustion gas only consis

42、ts ofO2and N2. This is approximately true provided CO productionis negligible, which is usually the case due to the abundantavailability of oxygen. As the composition of the incoming airis unlikely to change during a test, and as the temperatures inbuilding fires are usually not high enough to gener

43、ate notice-able amounts of nitrogen oxides by nitrogen fixation, the molefraction of O2in the air as measured by the analyzer prior to atest can be written on the basis of O2and N2exclusively. Themole fraction of O2in the exhaust combustion gases, asmeasured by the oxygen analyzer, can be written li

44、kewise. Asnitrogen is conserved and does not participate in the combus-tion reactions, the equations are derived on the basis of itsconservation.A3.3.2 In this case the rate of heat released (in kW) iscalculated as a function of the heat released per unit of oxygenconsumed (E, 12.1 MJ/kg of O2), the

45、 ratio of the molecularweight of oxygen (MO2, 32.0 kg/kmol) and molecular weightof the incoming air (Ma, generally taken as 28.97 kg/kmol) andthe mass flow of the incoming air (in kg/s). The flow measuredis that of the smoke within the exhaust duct and not that of theincoming air. In order to find a

46、 relation between the two, it isnecessary to define the oxygen depletion factor. The oxygendepletion factor is the fraction of the incoming air which isfully depleted of its oxygen (see Eq A4.4). It has beendemonstrated (see appendix in Test Method E 1354), that therate of heat release is a function

47、 of E, MO2, Ma, and the oxygendepletion factor, plus the factor, plus the expansion factor.A3.3.3 The expansion factor has to be assigned and arecommended value is 1.105, the value for methane. The valuefor propane is 1.084, carbon in dry air is 1.0 and hydrogen is1.21.A3.3.4 The resulting equation,

48、 Eq A4.5, is expected to beaccurate to within 65 % provided combustion is complete andall carbon is converted to CO2. Errors will be larger if CO orsoot production is considerable or if a significant amount of thecombustion products are other than CO2and H2O. It is unlikelythat these errors will be

49、of concern for the ICAL tests since O2is not limited.A3.4 Rate of Heat Release Measurement if Oxygen andCarbon Dioxide are being MeasuredA3.4.1 This case is similar to that covered inA3.3.Itisnowassumed that only water vapor is trapped before the specimenreaches the combustion gas analyzers.Again, the equations arederived on the basis of conservation of N2. The mole fractionof CO2in the incoming air is taken to be 440 ppm. A newequation is now needed, of course, for the oxygen depletionfactor: EqA4.7.Again the equation for rate of heat release (seeEq A4.5) is accurate to withi