1、CEN PREN*K2824 95 340Y589 0304943i 348 Edition approved for publication Comments should be sent within six months after the date of publication to AECMA Technopolis - 175, rue Jean-Jacques Rousseau 921 38 Issy-les-Moulineaux Cedex - FRANCE 1 995-0 1 -3 1 AECMA STANDARD prEN 2824 NORME AECMA Edition
2、P 1 AECMA NORM January 1995 DIT PAR LASSOCIATION EUROPENNE DES CONSTRUCTEURS DE MATRIEL AROSPATIAL Technopolis - 175, rue Jean-Jacques Rousseau - F-92138 Issy-les-Moulineaux Cedex - Tl. (1) 47.36.98.76 UDC : C7 Chairman M. Bottieli Descriptors : ENGLISH VERSION Aerospace series Burning behaviour of
3、non metallic materials under the influence of radiating heat and flames Determination of smoke density and gas components in the smoke of materials Test equipment, apparatus and media Srie arospatiale Luft- und Raumfahrt Comportement au feu Brandverhalten des matriaux non mtalliques sous laction de
4、chaleur rayonnante et de flammes Dtermination de la densit de fume et des composants des gaz de fume des matriaux quipement, appareils et moyens dessai nicht metallischer Werkstoffe unter Einwirkung von strahlender Wrme und Flammen Bestimmung der Rauchdichte und der Rauchgaskomponenten von Werkstoff
5、en Prfeinnchtung, Prfgerte und Prfmittel This “Aerospace Series“ Prestandard has been drawn up under the responsibility of AECMA (Association Europenne des Constructeurs de Matriel Arospatial). It is published on green paper for the needs of AECMA-Members. It has been technically approved by the exp
6、erts of the concerned Technical Committee following comment by the Member countries. Subsequent to the publication of this Prestandard, the technical content shall not be changed to an extent that interchangeability is affected, physically or functionally, without re-identification of the standard.
7、After examination and signature of the AECMA Standard Checking Centre (NPS) and formal agreement of the Official Services of the Member countries it will be submitted as a draft European Standard to CEN (European Committee for Standardization) for formal vote. aecma 199 - CEN PREN*2824 95 3404589 03
8、04942 284 Page 3 prEN 2824 : 1995 1 Scope This standard defines the test equipment, apparatus and media required for determination of the smoke density according to EN 2825 and the concentration of the gas components in the smoke according to EN 2826 due to pyrolitic decomposition of solid materials
9、 and composite materials of up to 25 mm in thickness under the influence of radiant heat only or with simultaneous flame application. This test method applies exclusively to materials whose specific standard requires this type of test. It cannot be substituted for the statutory tests required for a
10、final specific use of the material concerned. NOTE : The smoke gas density and the gas components in the smoke are determined according to the specific environmental and test conditions defined in this standard, in EN 2825 and EN 2826. No studies have been made up to now to determine whether the res
11、ults can be transferred to differing conditions, particularly to actual fire conditions. The inhalatory toxical risk and irritancy affect cannot be assessed by merely measuring the concentration of individual gas components in the smoke. 2 Normative references This European Standard incorporates by
12、dated or undated reference provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standar
13、d only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. IS0 2768-1 General tolerances - Part 1 : Tolerances for linear and angular dimensions without individual tolerance indications IS0 2768-2 General tolerances - Pa
14、rt 2 : Geometrical tolerances for features without individual tolerance indications EN 2743 Aerospace series - Reinforced plastics - Standard procedures for conditioning prior to testing 1) EN 2825 Aerospace series - Burning behaviour of non metallic materials - Determination of smoke density and ga
15、s components in the smoke of materials under the influence of radiating heat and flames - Determination of smoke density 1) EN 2826 Aerospace series - Burning behaviour of non metallic materials - Determination of smoke density and gas components in the smoke of materials under the influence of radi
16、ating heat and flames - Determination of gas components in the smoke 1) 3 Apparatus The test equipment comprises the test chamber described in 3.1, incorporating the devices specified in 3.2 to 3.8, as well as the ancillary equipment as detailed in 3.9 to 3.16. 1) Published as AECMA Prestandard at t
17、he date of publication of this standard Previous page is blank CEN PRENr2824 95 m 3404589 0304943 330 m Page 4 prEN 2824 : 1995 3.1 Test chamber See figure 1. The test chamber shall be designed to provide inside dimensions of (914 x 610 x 914) mm I3 mm for width, depth, and height respectively. The
18、interior surfaces shall consist of porcelain-enamelled metal or equivalent coated metal resistant to chemical attack and corrosion, and suitable for cleaning. Panels of 1 O mm thickness of porcelain-enamelled steel (interior surface laminated to a heat-resistant core and backed with corrosion-resist
19、ant steel (exterior surface) have been found suitable. Sealed windows shall be provided to accomodate a vertical photometric system. All other chamber penetrations shall also be sealed. When all openings are closed, the chamber shall be capable of developing and maintaining positive pressure during
20、the test period. In order to avoid an excessive increase of pressure in the chamber during testing an airtight safety disc is required, e. g. a sheet of aluminium foil of thickness not greater than 0,04 mm and a minimum area of 800 cm2 shall be provided in an opening of the chamber floor. 3.2 Radian
21、t heat furnace See figure 2. The furnace shall be located according to figure 3 equidistant from the front and back of lhe test chamber. The furnace control system shall maintain the required irradiance level of (25,O f 0,5) kW/m2 on the specimen surface for 20 min under steady-state conditions with
22、 the chamber door closed (to be demonstrated in calibration). The control system shall consist of a variable transformer or an equivalent control device, and a voltmeter or other means for monitoring the electrical input. Where line voltage fluctuations exceed f 2,5 %, a constant-voltage transformer
23、 is required to maintain the prescribed irradiance level. 3.3 Specimen holder Stops have to be provided to center the specimen accurately in front of the furnace. Figure 4 shows the construction of the holder. Two wires have to be placed in front of the specimen. 3.4 Photometric system The photometr
24、ic system shall conform to figure 5. The light path shall be oriented vertically to reduce influences resulting from stratification of the smoke generated by materials under test. The system shall conform to 3.4.1 to 3.4.3. 3.4.1 The light source shall be a 6 V incandescent lamp, operated at a fixed
25、 voltage to provide a brightness temperature of (2200 f 100) K. The light source shall be located in a sealed and light-tight box. This box shall contain the necessary optics to provide a collimated light beam of about 50 mm diameter passing vertically through the chamber. 3.4.2 A photomultiplier wi
26、th a spectral sensitivity rating of S-4 and a dark current of less than A shall be used. For amplification, a multirange amplifier shall be used, suitable to measure continuously the relative light intensity in percentage transmission over at least five orders of magnitude. The system shall have a l
27、inear response with respect to transmittance and an accuracy of f 3 % of the maximum reading on any range. A set of nine gelatin compensating filters varying from 0,l to 0,9 neutral density is mounted in a number of one or more as required in the optical measuring system to provide for correction of
28、 light source or photomultiplier aging and reduction in light transmission through discoloured or abraded optical windows. A light-tight box located directly opposite the light source shall be provided to mount the photodetector housing and the associated optics. A glass window shall be used to isol
29、ate the photodetector and its optics from the chamber atmosphere. CEN PRENs2824 75 m 3404587 0304944 057 m Page 5 prEN 2824 : 1995 3.4.3 In addition to the compensating filter as per 3.4.2, a neutral density filter ND-2 (grey filter) for extending the measuring range up to the optical density 6 is i
30、ncorporated in the smoke density chamber. Where values of smoke density D, 500 are measured, it may be necessary to provide a chamber window cover to prevent room light from being scattered into the photomultiplier and thus an incorrect higher transmission value. 3.5 Radiometer The radiometer accord
31、ing to figure 6 for standardizing the output of the radiant heat furnace shall be of the circular foil type 1). It shall have a stainless steel reflective heat shield with an aperture of about 38 mm on the front and a finned cooler mounted on the rear, to which compressed air is supplied in order to
32、 maintain a constant radiometer body temperature of (93 f 3) OC. The radiometer shall be connected directly to a recorder suitable for recording an irradiance signal of 25,O kW/m2 to an accuracy of 0.5 kW/m2. 3.6 Thermocouple A thermocouple shall be fixed to the centre of the inner surface of the ch
33、amber wall opposite the door. 3.7 A U-tube manometer with a range up to 1490 Pa water column shall be provided according to figure 7 in order to monitor chamber pressure and leakage. The pressure measurement point shall be mounted through a 25 mm diameter vent in the chamber. Manometer for chamber p
34、ressure measurements 3.8 Burner A six-tube burner as shown in figure 8 shall be used for the flaming exposure test. The burner shall be centered in front of and parallel to the specimen holder. The orifices of the two horizontal tubes shall be centered at (6,4 f 1,5) mm above the lower opening of th
35、e specimen holder and at a distance of (6,4 I 1,5) mm from the face of the specimen surface. Provision shall be made to move the burner out of the above-described position during non-flaming exposures. The fuel used shall be propane with a purity of not less than 95 %. Filtered oil-free air and prop
36、ane shall be fed through calibrated flowmeters and needle valves at (500 k 20) cm3/min for air and (50 f 3) cm3/min for propane and premixed prior to the entry into the burner (related to 23 OC and 0,l MPa). NOTE : The flowmeters shall be calibrated at regular frequency. The burner is properly adjus
37、ted if the blue flame cone of the horizontal flames is approx. 6 mm long. 3.9 Gas-sampling probes The gas sampling is carried out by means of three probes of about 5 mm inside diameter (see figure 9) reaching into the geometrical center of the chamber. The distance between the three probes shall not
38、 exceed 12 mm. These probes shall be connected to the gas-sampling supply lines by means of tube connectors provided at the top side of the test chamber. Lines not in use have to be shut. For direct measurement in the chamber, a rubber sleeve shall be provided to hold colorimetric test tubes on one
39、of the polypropylene probes inside the chamber. 1) The operation is described by : Gardon R, “An instrument for the measurement of Intense Thermal Radiation“, Review of Scientific Instruments, Vol. 24, 1953, pp. 366-370. CEN PREN82824 95 M 3404589 0304945 T93 M I Page 6 prEN 2824 : 1995 3.10 The sam
40、pling bags shall consist of a plastic film having a high chemical and mechanical resistance. The minimum volume shall be 10 dm3. The gas-sampling bags have to be constructed for minimal gas diffusion and water vapour transmissibility so that the gas composition changes by diffusion are negligible. P
41、lastic bags for gas sampling 3.1 1 Vacuum chamber Gas sampling shall be made in such a manner that the composition of the combustion gases will not be changed. A change in the gas composition may occur for instance when using unsuitable installation causing a loss of gas due to leakages or a condens
42、ation of the gases. A vacuum chamber, for example, is suitable for sampling. The filling of the bag is effected by the differential pressure between the vacuum chamber and the test chamber. After termination of the gas analysis, the bag is evacuated. A typical sampling arrangement is shown in figure
43、 9. The vacuum chamber is provided with two shut-off valves and and a transparent acrylic cover. The chamber is connected to the vacuum pump through a shut-off valve 0. The venting of the chamber is performed after filling of the sampling bags through a second shut-off valve 0. Evacuation pressure c
44、an be controlled by means of a vacuometer. The transparent cover is provided with a fixable coupling 6) for connection of the sampling bag. This is connected to the test chamber by a polypropylene tube with shut-off valve 0. The venting of the tube prior to gas sampling is effected through a bypass
45、provided on the tube close to the transparent cover, through a shut-off valve and a coupling . 3.12 Vacuum pump A vacuum pump shall be used which permits evacuation of the vacuum chamber according to 3.1 1 to 100 kPa within 60 s. 3.13 Alternative gas-sampling methods Alternatively to the method of f
46、illing the gas-sampling bags described in 3.1 1, other methods, e. g. filling of gas-sampling bags by a suitable pump, might be appropriate. 3.14 Colorimetric tubes The concentration of individual gas components in the smoke is normally determined using colorimetric tubes. 3.1 5 Dosing pump Dosing p
47、umps shall be used for measuring the gases with coiometric tubes with a feed rate of (100 f 3) cm3 of gas per stroke. 3.16 if gas components cannot be satisfactorily determined by means of colorimetric tubes, a wet analysis shall be performed. The following ancillary equipment is required : one or t
48、wo 100 ml scrubbers according to figure 10, a membrane pump, a gasmeter and the component-specific indicator and reference electrodes as well as a suitable device for measuring the pH values. Ancillary equipment for wet analysis - _ CEN PRENx2824 95 m 3404589 010494b 92T m Page 7 prEN 2824 : 1995 4
49、Cleaning of the test chamber The test chamber shall be periodically checked for contamination by visual inspection. Ammoniacal spray detergents and soft scouring pads shall be used for cleaning. Prior to each test, the exposed surfaces of the glass windows separating the photodetector and the light source housing from the interior of the chamber shall be cleaned with a suitable solvent fe. g. ethyl alcohol). Charred residues on the specimen holder and horizontal rods shall be removed between the tests. The cleanliness of the system shall be ver
