1、9009276 0021234 TT5 D ANSVASTM D 757-77 AMERICAN SOCIETY FOR TESTING AND MATERIALS 1816 R.C.St.Phil.dOlhia.Pa.19103 Remnted from the Annual Book of ASTM Standards,Copyright ASTM Il not listed in the current combined Index.will appear in the next edition.Standard Test Method for INCANDESCENCE RESISTA
2、NCE OF RIGID PLASTICS IN A HORIZONTAL POSITION1 reapproval.1.scope 1.1 This method provides for laboratory comparisons of the resistance of rigid plastics to an incandescent surface at 950*10C(1742*l 8 O F).It may supplement tests using a flame source of ignition,such as Method D 635.1.2 Caution-Dur
3、ing the course of com-bustion,gases or vapors,or both,are evolved which may be hazardous to personnel.Ade-quate precautions should be taken to protect the operator.NOTE 1-For a test on the burning rate of plastics in the form of thin sheets,reference should be made to Method D 568,Test for Rate of B
4、urning and/or Extent and Time of Burning of Flexible Plastics in a Vertical Position.z The bum-ing rate of sheet and plate insulation is covered in Methods D 229,Testing Sheet and Plate Materials Used for Electrical Insulation.z NOTE 2-The burning rate of plastic foams in a horizontal position mount
5、ed on a metal mesh screen can be determined by Method D 1692,Test for Rate of Burning and/or Extent and Time of Burning of Cellular Plastics Using a Specimen Supported by a Horizontal Screen.*1.3 This standard should be used to meas-ure and describe the properties of materials,products,or systems in
6、 response to heat and flame under controlled laboratory conditions,vtd should not be used for the descriution or appraisal of the fire hazard of materials,prod-ucts,or systems under actual fire conditions.3 NOTE The values stated in SI units are to be regarded as the standard.2.Applicable Documents
7、2.1 ASTM Standards:D 618 Conditioning Plastics and Electrical insulating Materials for Testingz D635 Test for Rate of Burning and/or Extent and Time of Burning of Self-Supporting Plastics in a Horizontal Posi-tioa2 This Standard is issued under the fixed designation D 757:the number immediately foll
8、owing the designation indicates the year of original adoption or.in the case of revision,the year of last revision.A number in parentheses indicates the year of last 3.Significance 3.1 This method provides comparative data,useful for research and production quality control work when it is desirable
9、to evaluate the resistance of plastics to an incandescent heat source.Correlation with burning characteris-tics under actual use conditions is not implied.3.2 The test results will vary with specimen thickness.Test results should be compared with data for a control material of known perform-ance and
10、 of comparable thickness.Sheet mate-rials that have been stretched during processing may relax during burning and give erratic results unless they are first heated above their temperature of deflection under load for a time sufficient to permit complete relaxation.3.3 This method is not intended to
11、be a criterion for fire hazard.The fire hazard created by materials depends upon the form and end use of the material.Assessment of fire hazard includes,but is not limited to,many factors,such as,ease of ignition,burning rate,flame spread,fuel contribution,intensity of burning,and products of combus
12、tion.4.Apparatus 4.I Test Chamber-A laboratory hood,equipped with a door for complete enclosure and a window for observing the test.The exhaust fan used to remove products of com-bustion shall be either turned off during the test This method is under the jurisdiction of ASTM Commit-tee D-20 on Plast
13、ics,and is the direct responsibility of Subcommittee D20.30 on Thermal Properties.Cumnt edition approved July 1,1977.Published September 1977.Onginally published as D 757-44.Last previous edition D 757-75.*Annual Book ofASTM Standarb.Part 35.This caveat has been placed in the standard in ac-cordance
14、 with a policy established by the ASTM Board of Directors in September 1973.The caveat will remain i n this standard until Committee E-39 on Fire Hazard Stand-ards has approved it as a fire hazard standard.I NOTICE:This standard has either been superseded and replaced by a new version or discontinue
15、d.Contact ASTM International(www.astm.org)for the latest information.H 9009276 4CTb or run at a low speed that will not cause currents of air to affect the test.4.2 Test Unit-A test unit consisting of parts shown in Figs.I and 2.The complete assembly is shown in Fig.3.The igniting source,A,shall be
16、a silicon carbide incandes-cent rod 8 mm in diameter and 279 mm in overall length,supported in upright holders,B,with ceramic and asbestos bushings.The silicon carbide rod with-metalized contact ends for attachment of terminal straps,is mounted on upright supports,C.4.2.I Variable Autotransformer for alternat-ing current or a rheostat for direct current that will provide 25 to 27 V at 14 to 15 A for heating the silicon carbide rod to 950+10C(1742+18F).A variable autotransformer that will deliver
