BS ISO 871-2006 en_2788 Plastics - Determination of ignition temperature using a hot-air furnace《塑料.热空气炉的点燃温度的测定》.pdf

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1、BRITISH STANDARD BS ISO 871:2006 Plastics Determination of ignition temperature using a hot-air furnace ICS 13.220.40; 83.080.01 BS ISO 871:2006 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 29 December 2006 BSI 2006 ISBN 0 580 49847 6 Nati

2、onal foreword This British Standard was published by BSI. It is the UK implementation of ISO 871:2006. It supersedes BS ISO 871:1996 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee PRI/26, Burning behaviour of plastics and rubbers. A list of organizat

3、ions represented on PRI/26 can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. Amendm

4、ents issued since publication Amd. No. Date CommentsINTERNATIONAL STANDARD ISO 871 Third edition 2006-11-15 Reference number ISO 871:2006(E) Plastics Determination of ignition temperature using a hot-air furnace Plastiques Dtermination de la temprature dallumage au moyen dun four air chaudBS ISO 871

5、:2006ii iii Contents Page 1 Scope 1 2 Normative references 1 3 Terms and definitions 1 4 Principle 2 5 Apparatus . 2 6 Location of thermocouples . 3 7 Test specimens 3 8 Procedure . 5 8.1 Flash-ignition temperature (FIT) 5 8.2 Spontaneous-ignition temperature (SIT) . 6 9 Precision . 6 10 Test report

6、 6 Annex A (informative) Results obtained by interlaboratory trials . 7 BS ISO 871:2006iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried ou

7、t through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO co

8、llaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International

9、Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the element

10、s of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 871 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 4, Burning behaviour. This third edition cancels and replaces the second edition (

11、ISO 871:1996), which has been technically revised. BS ISO 871:20061 Plastics Determination of ignition temperature using a hot-air furnace 1S c o p e 1.1 This International Standard specifies a laboratory method for determining the flash-ignition temperature and spontaneous-ignition temperature of p

12、lastics using a hot-air furnace. It is one of a number of methods in use for evaluating the reaction of plastics to the effects of ignition sources. 1.2 This method does not give a direct measure of the combustibility or rate of burning of a material or any definition of the safe upper limit of temp

13、erature for the plastics in use, and it should not be used alone to describe or appraise the fire hazard or fire risk of materials, products or assemblies under actual fire conditions. However, results of this test may be used as elements of a fire hazard or fire risk assessment which takes into acc

14、ount all of the factors pertinent to an assessment of the fire hazard of a particular end use. 1.3 Tests made under conditions of this method can be of considerable value in comparing the relative ignition characteristics of different materials. Values obtained represent the lowest ambient air tempe

15、rature that will cause ignition of the material under the conditions of this test. Test values are expected to rank materials according to ignition susceptibility under actual use conditions. 2 Normative references The following referenced documents are indispensable for the application of this docu

16、ment. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 291, Plastics Standard atmospheres for conditioning and testing ISO 13943, Fire safety Vocabulary IEC 60584-2:1982, Thermocouples

17、Part 2: Tolerances 3 Terms and definitions For the purposes of this document, the following terms and definitions apply in addition to those given in ISO 13943. 3.1 flash-ignition temperature FIT minimum temperature at which, under specified test conditions, sufficient flammable gases are emitted to

18、 ignite momentarily on application of a pilot flame 3.2 spontaneous-ignition temperature SIT minimum temperature at which, under specified test conditions, ignition is obtained by heating in the absence of any additional ignition source BS ISO 871:20062 3.3 glowing combustion combustion of a materia

19、l in the solid phase without flame but with emission of light from the combustion zone 4P r i n c i p l e A specimen of the material is heated in a hot-air ignition furnace using various temperatures within the heated chamber, and the flash-ignition temperature is determined with a small pilot flame

20、 directed at the opening in the top of the furnace to ignite evolved gases. The spontaneous-ignition temperature is determined in the same manner as the flash-ignition temperature, but without the pilot flame. 5 Apparatus 5.1 Hot-air ignition furnace, similar to that shown in Figure 1, consisting pr

21、imarily of an electrical heating unit and a specimen holder. 5.2 Furnace tube, with an inside diameter of and a length of , made of a ceramic that will withstand at least . The tube shall be positioned vertically so that it stands on the furnace floor above a plug for the removal of accumulated resi

22、due. 5.3 Inner ceramic tube, capable of withstanding at least , with an inside diameter of , a length of and a thickness of approximately , placed centrally inside the furnace tube and positioned above the furnace floor on three small refractory spacer blocks. The top shall be covered by a disc of h

23、eat-resistant material with a diameter opening in the centre which is used for observations and allows the passage of smoke and gases. The pilot flame shall be located immediately above the opening. 5.4 Outside air source, to supply clean air near the top of the annular space between the ceramic tub

24、es through a copper tube at a steady and controllable rate. The air shall be heated and circulated in the space between the two tubes and enter the inner ceramic tube at the bottom. The air flow shall be metered by a rotameter or other suitable device. 5.5 Electrical heating unit, made of 50 turns o

25、f nichrome wire or equivalent. The wires, contained within a mineral-fibre sleeve, shall be wound around the furnace tube and shall be embedded in heat- resistant cement. 5.6 Insulation, consisting of a layer of mineral-fibre wool approximately thick, and covered by a sheet- iron jacket. 5.7 Pilot i

26、gniter, consisting of a copper tube of nominal inside diameter attached to a supply of minimum purity propane and placed horizontally above the top surface of the disc cover. The pilot flame shall be adjusted to in length and centred above the opening in the disc cover. 5.8 Specimen support and hold

27、er, consisting of a metal specimen pan made of thick stainless steel and measuring in diameter by in depth, having a rounded bottom and held in a ring of approximately diameter stainless-steel welding rod. The ring shall be welded to a length of the same type of rod extending through the cover of th

28、e furnace, as shown in Figure 1. The bottom of the specimen pan shall be located down from the lower edge of the pilot igniter. 5.9 Thermocouples, in diameter, chromel-alumel (typeK) or iron-constantan (typeJ), for temperature measurement, connected to a calibrated recording instrument with a tolera

29、nce not exceeding . The thermocouple tolerance shall be in accordance with IEC 60584-2:1982, Table A.1, class 2, or better. 5.10 Heating control, consisting of a suitable variable transformer or an automatic controller connected in series with the heating coils. 100 mm5mm 240 mm 20 mm 750 C 750 C 75

30、 mm2mm 240 mm 20 mm 3mm 20 mm2mm 25 mm2mm 1,3 mm 0,1 mm 60 mm 2,0 mm 94 % 5mm1mm 20 mm2mm 0,7 mm 0,2 mm 40 mm2mm 15 mm2mm 2mm 185 mm2mm 0,5 mm 2 C BS ISO 871:20063 5.11 Timing device, having an accuracy of or better. 6 Location of thermocouples 6.1 Thermocouple (see Figure 1) measures the temperatur

31、e of the specimen. It is located as close as possible to the centre of the upper surface of the specimen when the specimen is in place within the furnace. The thermocouple wire is attached to the specimen support rod. 6.2 Thermocouple gives some indication of the temperature of the air travelling pa

32、st the specimen. It is located below the centre of the specimen pan. The thermocouple wire is conveniently attached to the specimen support rod. NOTE Thermocouple may also be installed through a hole drilled in the centre of the inspection plug below the specimen pan. 6.3 Thermocouple measures the t

33、emperature of the heating coil. It is located adjacent to the furnace heating coil and is used in preference to the inner-tube thermocouples because of its faster response. 7 Test specimens 7.1 Materials supplied in any form, including composites, may be used, but it is essential that the form is fu

34、lly described in the test report. NOTE 1 Specimens containing flame retardants and high levels of inorganic fillers may be difficult to evaluate. NOTE 2 The same material tested in different forms may give different results. 7.2 For materials having a density greater than , a specimen mass of shall

35、be used. Materials may be tested in the form of pellets or powder, as normally supplied for moulding. For sheet materials, cut the sheet into squares of maximum size and stack these to a height which gives the required specimen mass. For film materials, roll up a strip wide and of length sufficient

36、to give the required specimen mass. 7.3 For cellular materials having a density less than , remove any outer skin and cut specimens in the form of a block measuring . NOTE If the specimen is bulky and light and easily affected by the air flow in the furnace so that it may fall out of the tray, the s

37、pecimen may be bound by a thin wire. 7.4 Sufficient material is required for at least two determinations. 7.5 Condition the test specimens at and relative humidity for not less than prior to test, in accordance with ISO 291. 1s TC 1 T 1 TC 2 T 2 10 mm2mm TC 2 TC 3 T 3 100 kg/m 3 3,0 g 0,2 g (20 mm 2

38、 mm) (20 mm 2 mm) 20 mm2mm 100 kg/m 3 (20 mm 2 mm) (20 mm 2 mm) (50 mm 5 mm) 23 C 2 C (50 5) % 40 h BS ISO 871:20064 Dimensions in millimetres Figure 1 Cross section of hot-air ignition furnace BS ISO 871:20065 8 Procedure 8.1 Flash-ignition temperature (FIT) 8.1.1 Set the air velocity to by adjusti

39、ng the actual air-flow rate through the full section of the inner tube (5.3) at the furnace temperature to a value calculated in litres per minute from the following equation: where is the temperature in K. Ensure that the air-flow rate is maintained at of the calculated value. 8.1.2 Adjust the elec

40、tric current supplied to the heating coil (5.5) by means of the variable transformer or automatic controller (5.10), by reference to temperature , until the air temperature remains constant at the desired initial test temperature. NOTE A temperature of is used when no prior knowledge of the probable

41、 flash-ignition temperature range is available. Other starting temperatures may be selected if information about the material indicates a better choice. 8.1.3 Raise the specimen holder (see 5.8) to the cover opening and place the pan with the specimen into the ring of the holder. Ensure that thermoc

42、ouples and are in their correct position (see 6.1 and 6.2) and lower the pan into the furnace. Start the timer (5.11), ignite the pilot flame and watch for evidence of a flash or mild explosion of combustible gases which may be followed by burning of the specimen. 8.1.4 At the end of , lower or rais

43、e the temperature by , depending on whether ignition has or has not occurred, and repeat the test with a fresh specimen. 8.1.5 When the range within which the flash-ignition temperature lies has been determined, begin tests below the highest temperature within this range and continue by dropping the

44、 temperature in steps until the temperature is reached at which there is no ignition during a period. Key 1 thermocouple 2 support rod 3 refractory disc cover 4 thermocouple 5 gasket 6 thermocouple 7 heater terminals 8 pilot flame 9 air supply 10 metal fasteners 11 air-flow meter (not part of furnac

45、e) 12 air flow tangential to cylinder 13 specimen pan 14 mineral fibre wool 15 50 turns of No. 16 nichrome wire in heat-resistant cement 16 three refractory blocks to space inner tube and support it 17 inspection plug (removable) 18 thermal insulation (removable) Figure 1 Cross section of hot-air ig

46、nition furnace (continued) TC 2 TC 1 TC 3 25 mm/s q V q V = 6,62 293 T T 10 % T 3 T 2 400 C TC 1 TC 2 10 min T 2 50 C 10 C 10 C 10 min BS ISO 871:20066 8.1.6 Record as the flash-ignition temperature the lowest air temperature at which a flash is observed during the period. 8.2 Spontaneous-ignition t

47、emperature (SIT) 8.2.1 Follow the same procedure as in 8.1 but without the pilot flame. 8.2.2 Ignition will be evidenced by flaming or glowing combustion of the specimen. It may be difficult, with some materials, to detect spontaneous ignition visually when burning is by glowing combustion rather th

48、an flaming. In such cases, a rapid rise in temperature above temperature accompanied by a visual observation is the more reliable reference. 8.2.3 Record as the spontaneous-ignition temperature the lowest air temperature at which flaming or glowing combustion of the specimen is observed within the p

49、eriod. NOTE Determination of ignition temperatures is a process which is very sensitive to outer conditions. It is therefore necessary to keep strictly to the test conditions and procedures specified in this International Standard. 9P r e c i s i o n Precision data based on interlaboratory trials are given in Annex A. 10 Test report The test report shall include the following: a) a reference to this International