ASTM E1623-2014 Standard Test Method for Determination of Fire and Thermal Parameters of Materials Products and Systems Using an Intermediate Scale Calorimeter (ICAL)《使用中型量热计 (ICAL.pdf

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1、Designation: E1623 11E1623 14 An 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 E1623; the number immediately following

2、 the designation 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 () indicates an editorial change since the last revision or reapproval.1. Scope Scope*1.1 This fire-test

3、-response standard assesses the response of materials, products, and assemblies to controlled levels of radiantheat exposure with or without an external ignitor.1.2 The fire-test-response characteristics determined by this test method include the ignitability, heat release rates, mass lossrates, vis

4、ible smoke development, and gas release of materials, products, and assemblies under well ventilated conditions.1.3 This test method is also suitable for determining many of the parameters or values needed as input for computer fire models.Examples of these values include effective heat of combustio

5、n, surface temperature, ignition temperature, and emissivity.1.4 This test method is also intended to provide information about other fire parameters such as thermal conductivity, specificheat, radiative and convective heat transfer coefficients, flame radiation factor, air entrainment rates, flame

6、temperatures, minimumsurface temperatures for upward and downward flame spread, heat of gasification, nondimensional heat of gasification (1)2 and the flame spread parameter (see Test Method E1321). While some studies have indicated that this test method is suitable fordetermining these fire paramet

7、ers, insufficient testing and research have been done to justify inclusion of the corresponding testingand calculating procedures.1.5 The heat release rate is determined by the principle of oxygen consumption calorimetry, via measurement of the oxygenconsumption as determined by the oxygen concentra

8、tion and flow rate in the exhaust product stream (exhaust duct). The procedureis specified in 11.1. Smoke development is quantified by measuring the obscuration of light by the combustion product stream(exhaust duct).1.6 Specimens are exposed to a constant heating flux in the range of 0 to 50 kW/m2

9、in a vertical orientation. Hot wires are usedto ignite the combustible vapors from the specimen during the ignition and heat release tests. The assessment of the parametersassociated with flame spread requires the use of line burners instead of hot wire ignitors.1.6.1 Heat release measurements at lo

10、w heat flux levels (25 m in size.A2.2.7 A refrigerated column is the most successful approach to cool and dry the gases. Provide a drain plug to remove thecollected water from time to time. Alternative devices are also acceptable.A2.2.8 If carbon dioxide is to be removed, use carbon dioxide removal

11、media, as indicated in Fig. 6.A2.3 Combustion Gas AnalysisA2.3.1 Oxygen ConcentrationUse an oxygen analyzer, meeting the specifications under 6.4.9.2, preferably of the paramagnetictype.A2.3.2 Carbon Monoxide and Dioxide ConcentrationAnalyzers found suitable are nondispersive infrared analyzers. See

12、 GuideE800.A2.3.3 Other Combustion GasesUse Guide E800 for details of suitable analyzers when the concentrations of other combustiongases, such as water, total hydrocarbon, nitrogen oxide, hydrogen cyanide, or hydrogen chloride, are to be measured, for specialpurposes.A2.3.4 Time ShiftGas concentrat

13、ion measurements require the use of appropriate time shifts in order to account for gas transittime within the sampling system.A2.4 Smoke ObscurationA2.4.1 White Light System:A2.4.1.1 One suitable light measuring system based on white light has the following components: a lamp, plano convex lenses,a

14、n aperture, a photocell, and an appropriate power supply. Mount lenses, lamp, and photocell inside two housings, located on theexhaust duct, diametrically opposite each other. It has been found that a system consisting solely of a white light and a photocell,along the exhaust duct, across from each

15、other and at an angle to the vertical, is satisfactory in some cases.FIG. A2.4 Cross Type Gas Sampling ProbeE1623 1419A2.4.1.2 Use a lamp of the incandescent filament type, which operates at a color temperature of 2900 6 100 K. Supply the lampwith stabilized direct current, stable within 60.2 % (inc

16、luding temperature, short term and long term stability). Center the resultantlight 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 the focal length,f, of L2 so that d/f 0.04.A2.4.1.4 Place the aperture in the

17、focus of lens L2 according to Fig. 7.A2.4.1.5 Use a detector with a spectrally distributed response according to the CIE photopic curve and linear within 5 % over anoutput range of at least 3.5 decades. Check this linearity over the entire range of the instrument periodically with calibrated optical

18、filters.A2.4.1.6 The system described as follows is an example of a light measuring system that has been found to be satisfactory:(1)lensesPlano convex: diameter 40 mm, focal length 50 mm; (2) lampOsram Halo Stars, 64410, 6 V, 10 W, or equivalent;(3)photocellUnited Detector Technology, PIN 10AP, or

19、equivalent; and (4)voltage supply Gresham Lion Ltd, Model G 012,or equivalent.A2.4.1.7 Design a system that is easily purged against soot deposits. The use of holes in the periphery of the two housings is ameans of achieving this objective.NOTE A2.1This system is different from the traditional smoke

20、 obscuration measurement system in Test Method E662.A2.4.2 Laser SystemAn acceptable alternate system for measurements of smoke obscuration uses a laser beam. An 0.5 to 2.0mW helium-neon laser beam is projected across the exhaust duct. Couple the two halves of the device rigidly together (see Fig.8)

21、.A3. CONSIDERATIONS FOR HEAT RELEASE MEASUREMENTSA3.1 Measurement of Rate of Heat Release by Oxygen ConsumptionA3.1.1 IntroductionIn 1917, Thornton (2) showed that for a large number of organic fuels, a more or less constant net amountof heat is released per unit of oxygen consumed for complete comb

22、ustion. Huggett (3) obtained an average value for this constantof 12.1 MJ/kg of O2. It is appropriate to use this value for practical applications; it is accurate, with very few exceptions, to within6 5 %.A3.1.2 Thorntons rule indicates that it is sufficient to measure the oxygen consumed in a combu

23、stion system in order to determinethe net heat released. This is particularly useful for full-scale fire test applications. For example, for compartment fires, the oxygenconsumption technique is much more accurate and easier to implement than methods based on measuring all the terms in a heatbalance

24、 of the compartment.A3.1.3 Perhaps the first application of the O2 consumption principle in fire research was by Parker (8) using Test Method E84tunnel test. Later, Sensenig applied it to an intermediate scale room test (9). During the late seventies and early eighties, the O2consumption technique w

25、as refined at the National Institute for Standards and Technology (NIST, formerly National Bureau ofStandards).Apaper by Parker (10) gives equations to calculate rate of heat release rate by O2 consumption for various applications.The technique is now used extensively in many laboratories all over t

26、he world, both in bench-scale (11) and full-scale (ProposalP147 and (12) fire test applications.A3.1.4 The objective of this section is to provide a comprehensive set of equations and guidelines to determine the rate of heatrelease rate in ICAL fire tests based on the O2 consumption principle. The a

27、pproach followed here is somewhat different fromParker (10) as the emphasis is on intermediate-scale fire test applications and the use of volumetric flows is avoided. Volumetricflows require specification of temperature and pressure. Various investigators have used different combinations of referen

28、cepressure and temperature. This leads to confusion, which is greatly minimized if mass flows are used.E1623 1420A3.1.5 The basic requirement is that all combustion products be collected in a hood and removed through an exhaust duct. At adistance downstream of the hood sufficient for adequate mixing

29、, both flow and composition of the combustion gases are measured.It is assumed here that it is not possible to measure the air flow into the system, as this is generally the case for full-scale fire tests.The differences in treatment and equations to be used are mainly due to the extent to which com

30、bustion gas analysis is made. Atleast O2 shall be measured. However, heat release rate measurements will be more accurate by measuring CO2 and CO additionally.A3.1.6 It must be emphasized that the analysis is approximate. The following list describes the main simplifying assumptionsmade:A3.1.6.1 The

31、 amount of energy released by complete combustion per unit of oxygen consumed is taken as: E = 12.1 MJ/kg ofO2.A3.1.6.2 All combustion gases are considered to behave as ideal gases, in other words one mole of any gas is assumed to occupya constant volume at the same pressure and temperature.A3.1.6.3

32、 Incoming air consists of O2, CO2, H2O, and N2.All “inert” gases, which do not take part in the combustion reaction, arelumped into the nitrogen.A3.1.6.4 O2, CO2, and CO are measured on a dry basis, in other words water vapor is removed from the specimen beforecombustion gas analysis measurements ar

33、e made.A3.1.7 In the analysis to follow, initial emphasis will be placed on the flow measurement. Equations to calculate flow areapplicable, unless otherwise indicated, irrespective of the configuration of the combustion gas analysis system. In subsequentsections, distinction is made between various

34、 combustion gas analyzer combinations.A3.2 Flow MeasurementsA3.2.1 Mainly two techniques are used to measure mass flow in the exhaust duct of ICAL fire tests.A3.2.2 The first technique measures mass flow by the pressure drop across, and temperature at, an orifice plate (see Eq A4.1). Ifthe test is c

35、onducted within a narrow range of conditions, the orifice plate coefficient, C, is approximately constant. Determine thevalue of the orifice plate coefficient using a gas burner calibration or an alternative method that provides equivalent results.However, if flows are varied during a test or if tem

36、perature changes are considerable, the effects on C of the Reynolds number andpressure at the downstream side of the orifice plate must be taken into account. Information on such corrections and on variousdesign options (for example location of the pressure taps) are found in Ref (13).A3.2.3 The oth

37、er technique is to measure velocity at one point in the duct, usually along the center line. The flow is then calculatedusing a predetermined shape of the velocity profile in the duct. The latter is obtained by measuring velocity at a sufficient numberof representative points over the diameter or cr

38、oss section of the duct prior to any fire tests. Detailed procedures to obtain thisprofile are described in (14). Usually, conditions in intermediate-scale fire tests are such that the flow in the duct is turbulent,resulting in a shape factor kc (equals ratio of the average velocity to the velocity

39、along the centerline) close to 1.A3.2.4 Due to considerable soot production in many fires, pitot static tubes cannot be used because of the potential for cloggingof the holes. In order to deal with this problem, a more robust bidirectional probe was designed by McCaffrey and Heskestad (15).This invo

40、lves measuring the differential pressure across the probe and the centerline velocity (see Eq A4.2), and is valid in therange of Reynolds numbers, Re: 40 3800. In this case f(Re) is taken as a constant (1.08), which greatly simplifies the calculations.This equation (see Eq A4.2) is preferred to Eq A

41、4.1 for intermediate scale measurements of heat release rate. Further details ofthis and of all other calculations discussed in this annex are found in a paper by Janssens (16). For additional details, see also ISO9705.E1623 1421A3.3 Rate of Heat Release Rate Measurement if Only Oxygen is MeasuredA3

42、.3.1 In this case all water vapor and CO2 are eliminated by the use of appropriate filtering media. This leads to the assumptionthat the specimen combustion gas only consists of O2 and N2. This is approximately true provided CO production is negligible,which is usually the case due to the abundant a

43、vailability of oxygen. As the composition of the incoming air is unlikely to changeduring a test, and as the temperatures in building fires are usually not high enough to generate noticeable amounts of nitrogenoxides by nitrogen fixation, the mole fraction of O2 in the air as measured by the analyze

44、r prior to a test can be written on the basisof O2 and N2 exclusively. The mole fraction of O2 in the exhaust combustion gases, as measured by the oxygen analyzer, can bewritten likewise. As nitrogen is conserved and does not participate in the combustion reactions, the equations are derived on theb

45、asis of its conservation.A3.3.2 In this case the rate of heat released heat release rate (in kW) is calculated as a function of the heat released per unit ofoxygen consumed (E,12.1 MJ/kg of O2), the ratio of the molecular weight of oxygen (MO2, 32.0 kg/kmol) and molecular weightof the incoming air (

46、Ma, generally taken as 28.97 kg/kmol) and the mass flow of the incoming air (in kg/s). The flow measuredis that of the smoke within the exhaust duct and not that of the incoming air. In order to find a relation between the two, it isnecessary to define the oxygen depletion factor. The oxygen depleti

47、on factor is the fraction of the incoming air which is fullydepleted of its oxygen (see Eq A4.4). It has been demonstrated (see appendix in Test Method E1354), that the rate of heat releaserate is a function of E, MO2, Ma, and the oxygen depletion factor, plus the factor, plus the expansion factor.A

48、3.3.3 The expansion factor has to be assigned and a recommended value is 1.105, the value for methane. The value for propaneis 1.084, carbon in dry air is 1.0 and hydrogen is 1.21.A3.3.4 The resulting equation, EqA4.5, is expected to be accurate to within65 % provided combustion is complete and all

49、carbonis converted to CO2. Errors will be larger if CO or soot production is considerable or if a significant amount of the combustionproducts are other than CO2 and H2O. It is unlikely that these errors will be of concern for the ICAL tests since O2 is not limited.A3.4 Rate of Heat Release Rate Measurement if Oxygen and Carbon Dioxide are being MeasuredA3.4.1 This case is similar to that covered in A3.3. It is now assumed that only water vapor is trapped before the specimen reachesthe combustion gas analyzers. Again, the equations are derived on the basis of cons