1、Designation: E1623 14E1623 16 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*1.1 This fire-test-respo
3、nse 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, visible s
4、moke 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 combustion, sur
5、face 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 temper
6、atures, 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 parameters, i
7、nsufficient 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 concentration a
8、nd 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 heatingheat flux in the range of 0 to 50 kW/m2 in
9、 a vertical orientation. Hot wires areused to ignite the combustible vapors from the specimen during the ignition and heat release tests. The assessment of theparameters associated with flame spread requires the use of line burners instead of hot wire ignitors.1.6.1 Heat release measurements at low
10、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 me
11、dia, 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 G
12、uideE800.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.FIG. A2.2 Horizontal Gas Sampling
13、 ProbeE1623 1618A2.3.4 Time ShiftGas concentration measurements require the use of appropriate time shifts in order to account for gas transittime within the sampling system.FIG. A2.3 Cross Type Sampling ProbeFIG. A2.4 Cross Type Gas Sampling ProbeE1623 1619A2.4 Smoke ObscurationA2.4.1 White Light S
14、ystem:A2.4.1.1 One suitable light measuring system based on white light has the following components: a lamp, plano convex lenses,an aperture, a photocell, and an appropriate power supply. Mount lenses, lamp, and photocell inside two housings, located on theexhaust duct, diametrically opposite each
15、other. It has been found that a system consisting solely of a white light and a photocell,along the exhaust duct, across from each other and at an angle to the vertical, is satisfactory in some cases.A2.4.1.2 Use a lamp of the incandescent filament type, which operates at a color temperature of 2900
16、 6 100 K. Supply the lampwith stabilized direct current, stable within 60.2 % (including 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
17、 to the focal length,f, of L2 so that d/f 0.04.A2.4.1.4 Place the aperture in the 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 line
18、arity over the entire range of the instrument periodically with calibrated opticalfilters.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, 644
19、10, 6 V, 10 W, or equivalent;(3)photocellUnited Detector Technology, PIN 10AP, or 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 ach
20、ieving this objective.NOTE A2.1This system is different from the traditional smoke 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
21、the exhaust duct. Couple the two halves of the device rigidly together (see Fig.8).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 co
22、nstant net amountof heat is released per unit of oxygen consumed for complete combustion. 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 Thornt
23、ons rule indicates that it is sufficient to measure the oxygen consumed in a combustion 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
24、easier to implement than methods based on measuring all the terms in a heatbalance 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 tes
25、t (9). During the late seventies and early eighties, the O2consumption technique was refined at the National Institute for Standards and Technology (NIST, formerly National Bureau ofE1623 1620Standards). A paper by Parker (10) gives equations to calculate heat release rate by O2 consumption for vari
26、ous applications. Thetechnique is now used extensively in many laboratories all over the world, both in bench-scale (11) and full-scale (Proposal P147and (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 he
27、at releaserate in ICAL fire tests based on the O2 consumption principle. The approach followed here is somewhat different from Parker (10)as the emphasis is on intermediate-scale fire test applications and the use of volumetric flows is avoided. Volumetric flows requirespecification of temperature a
28、nd pressure. Various investigators have used different combinations of reference pressure andtemperature. This leads to confusion, which is greatly minimized if mass flows are used.A3.1.5 The basic requirement is that all combustion products be collected in a hood and removed through an exhaust duct
29、. At adistance downstream of the hood sufficient for adequate mixing, 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 treatmen
30、t and equations to be used are mainly due to the extent to which combustion 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 follow
31、ing list describes the main simplifying assumptionsmade:A3.1.6.1 The 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 o
32、ccupya constant volume at the same pressure and temperature.A3.1.6.3 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 rem
33、oved from the specimen beforecombustion gas analysis measurements are 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 analysi
34、s system. In subsequentsections, distinction is made between various 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,
35、 and temperature at, an orifice plate (see Eq A4.1). Ifthe test is conducted 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 equ
36、ivalent results.However, if flows are varied during a test or if temperature 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
37、 location of the pressure taps) are found in Ref (13).A3.2.3 The other 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
38、 a sufficient numberof representative points over the diameter or cross 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 sh
39、ape factor kc (equals ratio of the average velocity to the velocity 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 bidire
40、ctional probe was designed by McCaffrey and Heskestad (15).This involves measuring the differential pressure across the probe and the centerline velocity (see Eq A4.2), and is valid in theE1623 1621range of Reynolds numbers, Re: 40 3800. In this case f(Re) is taken as a constant (1.08), which greatl
41、y simplifies the calculations.This equation (see Eq A4.2) is preferred to Eq A4.1 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.A3.
42、3 Heat Release Rate Measurement if Only Oxygen is MeasuredA3.3.1 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 i
43、s negligible,which is usually the case due to the abundant availability 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, t
44、he mole fraction of O2 in the air as measured by the analyzer 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
45、 the combustion reactions, the equations are derived on thebasis of its conservation.A3.3.2 In this case the heat release rate (in kW) is calculated as a function of the heat released per unit of oxygen consumed(E,12.1 MJ/kg of O2), the ratio of the molecular weight of oxygen (MO2, 32.0 kg/kmol) and
46、 molecular weight of the incoming air(Ma, generally taken as 28.97 kg/kmol) and the mass flow of the incoming air (in kg/s). The flow measured is that of the smokewithin the exhaust duct and not that of the incoming air. In order to find a relation between the two, it is necessary to define theoxyge
47、n depletion factor. The oxygen depletion factor is the fraction of the incoming air which is fully depleted of its oxygen (seeEq A4.4). It has been demonstrated (see appendix in Test Method E1354), that the heat release rate is a function of E, MO2, Ma,and the oxygen depletion factor, plus the facto
48、r, plus the expansion factor.A3.3.3 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 c
49、ombustion is complete and all 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 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 deri
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1