DIN_53438-3英文版本

DIN 53438 Part 3 Testing of combustible materials Response to ignition by a small flame Surface ignition Dimensions in mm 1.Field of application This standard specifies the method of test for determining the response of material to surface ignition, refered to in brief as method F. See DIN 53438 Part 1.DIN 50050 and DIN 50051 for general information, explanatory notes, concepts and apparatus. See DIN 53438 Part 2 for edge igniting(method K). 2 Test pieces 2.1Take or prepare 10 test pieces (see subclause 4.1) from the product to be tested. In the case of anisotropic products, take note of the direction of sampling and include this information in the test report. 2.2 The test pieces shall be 230mm in length by 90mm in width. Their thickness shall depend on the specifications for the product concerned or shall be agreed upon. Use only test pieces the thickness of which does not deviate from the thickness of all other test pieces by more than (10% at any point. If the given permissible deviation is exceeded, the test report shall contain a note to that effect. 2.3 Make gauge marks on each of the test pieces at the following distances from what will be lower edge when the test pieces is in the test position :40mm(lower guage mark) and 190mm (upper gauge mark) 3 Conditioning of test pieces Prior to testing, the test pieces shall be stored in a DIN 50014-23/50-2 standard atmosphere. The duration of the conditioning period shall depend on the specification for the product under test, or shall be agreed upon. If no other specification obtains, then conditioning shall last for not less than 24h. 4 Procedure 4.1 The test shall be carried out on five test pieces. If no clear classification in accordance with sub clause 5.2 is possible, the test shall be repeated on five further test pieces 4.2 In the test area (laboratory) and exhaust hood, the ambient temperature shall, at least at the start of each test, lie between 18 and 28℃ as specified in DIN 50014. 4.3 Measure the thickness of the test pieces on the central longitudinal axis at distances of 40,100and 160mm from their edges to (0.1mm, or to (0.01mm in the case of test pieces less than 1mm thick. Lay the test piece in the two-part frame(see DIN 53438 Part 1, June 1984 edition, subclause 4.1.3) so that the lower edge of the test piece coincides with the lower edge of the frame(see figure). Join the two parts of the frame using threaded or spring clips and suspend the frame vertically from the suspension device positioned in the test chamber. With the burner (see DIN 53438 Part 1, June 1984 edition ,subclause 4.1.1) set in the vertical position , anjust the flame to a height of 20 mm. With the flame at this height, leave the burner to burn for at least one minute prior to commencing the test, readjusting the height, if necessary, at the end of this period. Then incline the burner through 45°and close the test chamber. 4.4 Slide the burner towards the test piece so that the flame impinges on the test piece in the centre of the lower gauge mark..Then distance between the front edge of the stabilizer and the surface of the test piece shall be 5mm(see figure). Apply the flame to the test piece for 15 seconds and then withdraw the burner. Take particular care to ensure that no disturbing draughts are created as a result. Measure the burning time (see DIN 53438 Part 1, for concept)from the initial application of the flame until the flame on the burning test piece ceases to burn, or until the tip of the flame on the burning test piece reaches the upper gauge mark. If the test piece continues to glow after the flame is extinguished, measure the afterglow time(see DIN 53438 Part 1, for concept)from the extinction of the flame on the test piece until glowing ceases. Any particular observations during the course of the test shall ba noted in the test report; these may include formation of smoke and soot, material falling and dripping from the test piece and whether such material continues to burn on reaching the floor of the chamber, appearance of the molten edge(e.g. whether a frame work is left),burning on both sides or just on one, shrinkage of the test piece away from the flame, burning of a hole through the test piece, extent of burning .Then assess the test piece in accordance with clause 5 and assign it to a class. 4.5 The frame and the suspension device shall have cooled to an ambient temperature of 18 to 28, as specified in DIN 50014, before a subsequent test may be commenced. 5 Assessment and evaluation 5.1 Each of the test piece tested asdescribed in subclause 4.4 shall be assessed in accordance with table below: Evaluation Class The flame tip on the burning test piece does not reach the upper gauge mark(the flame is extinguished beforehand) F1 The flame tip on the burning test piece reaches the upper gauge mark in 20 seconds or longer. F2 The flame tip on the burning test piece reaches the upper gauge mark in less than 20 seconds. F3 Then mean thickness of the test piece shall be suffixed to the indication of the class, the two values being separated by an oblique stroke. Thicknesses 1mm or greater shall be rounded to within 0.1mm, and thicknesses less than 1mm shall be rounded to within 0.01mm. (For example: F1/3.5 mm signifies class F1(face ignition) for a test piece with an average thickness of 3.5mm.) 5.2 Evaluation in accordance with subclause 5.1shall be subject to the following specifications: 1 If all test pieces of a material can be assigned to the same class, the material shall be said to belong to that class. 2 If two of the five test pieces of a material are to be assigned to an inferior class, the material shall be said to belong to the inferior class. 3 If one of the five test pieces is to be assigned to an inferior class, the test shall be repeated on five new test pieces of the same material. If retesting results in one or more test pieces being assigned to an inferior class, the material shall be said to belong to the inferior class. 5.3 Average the burning times of the test pieces tested in accordance with subclause 4.4, and state the mean value, in seconds, rounded to the nearest second, in the test report as the mean burning time of the material. Average the afterglow times of the test pieces tested in accordance with subclause 4.4 and state the mean value, in seconds, rounded to the nearest seconds, in the test report as the mean afterglow time of the material. 6.Test report The test report shall refer to this standard and include the following particulars: a) type and designation of the product(material) tested; b) method and date of production of the test pieces, indicating the direction of sampling, if relevant; c) conditioning of the test pieces; d) statement of which surface was tested, or whether both were tested; e) mean thickness obtained from measuring all test pieces in accordance with subclause 4.3; minimum and maximum thicknesses measured; f) mean burning time; g) mean afterglow time; h) class, indicating the mean measured thickness, as specified in subclause 5.1 i) point of flame impingence in the case of test pieces thicker than 3 mm; j) particular observations made during the test as described in subclause 4.4。 k) date of test.