ASD-STAN PREN 3475-407-2008 Aerospace series Cables electrical aircraft use Test methods Part 407 Flammability (Edition P 4)《航空航天系列 航空器用电缆的试验方法 第407部分 易燃性 第P4版》.pdf

1、ASD STANDARD NORME ASD ASD NORM prEN 3475-407 Edition P 4 December 2008 PUBLISHED BY THE AEROSPACE AND DEFENCE INDUSTRIES ASSOCIATION OF EUROPE - STANDARDIZATION Avenue de Tervuren, 270 - B-1150 Brussels - Tel. + 32 2 775 8126 - Fax. + 32 2 763 3565 - www.asd-stan.orgICS: 49.060 Supersedes edition P

2、 3 August 2004 Will supersede EN 3475-407:2005 Descriptors: ENGLISH VERSION Aerospace series Cables, electrical, aircraft use Test methods Part 407: Flammability Srie arospatiale Cbles lectriques usage aronautique Mthodes dessais Partie 407 : Tenue la flamme Luft- und Raumfahrt Elektrische Leitungen

3、 fr Luftfahrtverwendung Prfverfahren Teil 407: Entflammbarkeit This “Aerospace Series“ Prestandard has been drawn up under the responsibility of ASD-STAN (The AeroSpace and Defence Industries Association of Europe - Standardization). It is published for the needs of the European Aerospace Industry.

4、It has been technically approved by the experts of the concerned Domain following member comments. 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

5、the standard. After examination and review by users and formal agreement of ASD-STAN, it will be submitted as a draft European Standard (prEN) to CEN (European Committee for Standardization) for formal vote and transformation to full European Standard (EN). The CEN national members have then to impl

6、ement the EN at national level by giving the EN the status of a national standard and by withdrawing any national standards conflicting with the EN. Edition approved for publication 31 December 2008 Comments should be sent within six months after the date of publication to ASD-STAN Electrical Domain

7、 Copyright 2008 by ASD-STAN prEN 3475-407:20082 Contents Page Foreword2 1 Scope 3 2 Normative references 3 3 Equipment 3 4 Procedures .4 5 Acceptance criteria8 Foreword This standard was reviewed by the Domain Technical Coordinator of ASD-STANs Electrical Domain. After inquiries and votes carried ou

8、t in accordance with the rules of ASD-STAN defined in ASD-STANs General Process Manual, this standard has received approval for Publication. prEN 3475-407:20083 1 Scope This standard specifies two methods of determining the flammability characteristics of a finished cable. It shall be used together

9、with EN 3475-100. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 3475-

10、100, Aerospace series Cables, electrical, aircraft use Test methods Part 100: General. FAR 25, Airworthiness standards Transport category airplanes. JAR 25, Large aeroplanes. 3 Equipment The following equipment shall be required for these tests: a) Test chamber: this shall be a chamber measuring not

11、 less than 700 mm high 300 mm wide 300 mm deep, open at the top, open at the front and situated in a draught-free environment but with sufficient air supply to provide normal combustion. General arrangements are shown in Figures 1 and 2. b) Bunsen type gas burner: the burner shall have a 6 mm inlet,

12、 a needle valve in the base for gas adjustment, a nominal bore of 9 mm and a barrel of approximately 100 mm above the air inlets. The gas supply shall be capable of achieving the test requirements defined in 4.1.2 and 4.2.2. WARNING NOTE Care should be exercised in setting up and performing this tes

13、t as toxic fumes may be given off during combustion. The test chamber shall be placed in a fume cabinet that will allow evacuation of gaseous products of combustion at the end of the test. prEN 3475-407:20084 4 Procedures 4.1 Method 1 4.1.1 Preparation of test specimens Cut two sets of three specime

14、ns each, approximately 900 mm in length, consecutively from the same coil. Strip each end and place them in an atmosphere of (50 5) % relative humidity at a temperature of (21 3) C for a period of not less than 24 h. Keep the specimens in the conditioning area until just prior to testing. 4.1.2 Flam

15、e temperature 4.1.2.1 Adjust the Bunsen burner to produce a flame with an inner blue cone approximately one-third of the overall flame height. Insert a bare copper wire of (0,7 0,025) mm diameter, and having a free length of not less than 100 mm, into the flame, the end of the wire being immediately

16、 above the tip of the inner cone. NOTE For initial setting-up purposes, an overall flame height of approximately 75 mm may be found suitable. 4.1.2.2 Adjust the burner so that the wire starts to melt within 4 s to 6 s of being inserted into the flame. NOTE Alternatively for 4.1.2.1 and 4.1.2.2, a 0,

17、8 mm to 0,81 mm diameter wire may be used in which case adjust the burner so that the wire starts to melt within 7 s to 9 s. 4.1.3 Mounting configuration 4.1.3.1 Mount the specimen in the test chamber as shown in Figure 1 at an angle of (60 2) to the horizontal, parallel to, and approximately 150 mm

18、 from the front end of the test chamber. Clamp the conductor at the bottom of the apparatus. Pass the cable over the upper pulley and attach it to a weight which is just sufficient to keep the specimen straight within the test zone. prEN 3475-407:20085 Key 1 Box construction aluminium alloy 3,15 mm

19、6 600 - Distance between reference marks 2 Upper datum point 7 Flame application point (flame centre datum) 3 Pulley support bracket (low thermal conductivity) 8 Bottom clamp support (low thermal conductivity) 4 Support frame open at front 9 Bunsen burner support (low thermal conductivity) 5 Weights

20、 as required a approx. Figure 1 prEN 3475-407:20086 4.1.3.2 Make a mark 200 mm above the lower clamp point and position the burner in the plane of this mark, perpendicular to the specimen and directed towards the specimen at an angle of 30 to the vertical plane as shown in Figure 1, i.e. at 90 to th

21、e axis of the cable such that the flame will impinge directly onto the 200 mm mark. 4.1.3.3 Set the distance of the burner from the specimen such that the tip of the inner cone of the flame is immediately below the specimen. 4.1.4 Flame application Apply the flame to each specimen of a set for a per

22、iod of 15 s and then immediately remove the burner. Apply the flame to each specimen of the second set for a period of 30 s and then immediately remove the burner. NOTE 1 For thin wall insulation the time of 15 s is considered more severe, as all the insulation can be carbonized in less than 30 s. N

23、OTE 2 Nevertheless a test at 30 s is also necessary to assess FAR/JAR 25 requirements. NOTE 3 The 15 s value was introduce in P2 issue when 30 s value was initially removed. 4.2 Method 2 4.2.1 Preparation of test specimens Cut three specimens, approximately 450 mm in length, consecutively from the s

24、ame coil. Strip each end and place them in an atmosphere of (50 5) % relative humidity at a temperature of (21 3) C for a period of not less than 24 h. Keep the specimens in the conditioning area until just prior to testing. Remove 50 mm of insulation from one end of the specimen and mount it as sho

25、wn in Figure 2. 4.2.2 Flame temperature Adjust the Bunsen burner to produce a 38 mm high soft yellow flame. 4.2.3 Mounting configuration Mount the specimen vertically in the test chamber as shown in Figure 2. Fix the lower end of the conductor to the support bar and apply the fine wire to the conduc

26、tor at the junction with the insulation. Pass the cable over the upper pulley and attach it to a weight which is just sufficient to keep the specimen straight within the test zone. prEN 3475-407:20087 Key 1 Clamp 4 Specimen 2 Pulley 5 Fine wire 3 Weight 6 Stripped conductor 50 mm Figure 2 Apply the

27、38 mm high yellow flame from the Bunsen burner to the specimen at the junction of the insulation and the bare conductor in such a manner that the lower end of the insulation is located half-way (19 mm) into the flame as shown in Figure 2. prEN 3475-407:20088 4.2.4 Flame application Apply the flame t

28、o the specimen for a period of 15 s and then immediately remove the burner. 4.3 Completion of test (methods 1 and 2) 4.3.1 After the burner has been removed, note the time taken for all flaming of the specimen to cease and the length of specimen cable which has been burnt. 4.3.2 Repeat the procedure

29、 for the two other specimens. 5 Acceptance criteria 5.1 Method 1 During ignition and combustion, there shall be no flaming droplets or particles falling from the specimen. After the burner has been removed, the specimen cable shall cease flaming within the time specified in the product standard and

30、within a total burnt length of 50 mm. The burn length shall be measured from the downward extent of propagation to the upward extent of propagation and including damage caused by the burner itself. 5.2 Method 2 During the test, there shall be no flaming droplets or particles falling from the specime

31、n. After the burner has been removed, the specimen cable shall cease flaming within 10 s and within a total burnt or charred length of 75 mm. The burnt length is the distance from the original junction of the insulation and the bare conductor, indicated by the bend made in the conductor, to the farthest point of damage. NOTE Where a product standard specifies only one burn time, this shall be taken as referring to method 1.