1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL UL 746B Polymeric Materials Long Term Property EvaluationsUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM ULUL COPYRIGHTED MATERIAL NOT A
2、UTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL UL Standard for Safety for Polymeric Materials Long Term Property Evaluations, UL 746B Fourth Edition, Dated April 4, 2013 SUMMARY OF TOPICS This revision of the Fourth Edition of ANSI/UL 746B is being issued to address th
3、e following change in requirements: Relative humidity tolerance for sample conditioning Example calculation for Related Material Text that has been changed in any manner or impacted by ULs electronic publishing system is marked with a vertical line in the margin. Changes in requirements are marked w
4、ith a vertical line in the margin and are followed by an effective date note indicating the date of publication or the date on which the changed requirement becomes effective. The revised requirements are substantially in accordance with Proposal(s) on this subject dated December 20, 2013. All right
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9、rd on the purchasers computer system. The requirements in this Standard are now in effect, except for those paragraphs, sections, tables, gures, and/or other elements of the Standard having future effective dates as indicated in the note following the affected item. The prior text for requirements t
10、hat have been revised and that have a future effective date are located after the Standard, and are preceded by a SUPERSEDED REQUIREMENTS notice. JULY 16, 2014 UL 746B tr1UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL JULY 16, 2014 UL 746B
11、tr2 No Text on This PageUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL April 4, 2013 (Title Page Reprinted: July 16, 2014) 1 UL 746B Standard for Polymeric Materials Long Term Property Evaluations First Edition September, 1975 Second Editio
12、n June, 1979 Third Edition August, 1996 Fourth Edition April 4, 2013 This ANSI/UL Standard for Safety consists of the Fourth Edition including revisions through July 16, 2014. The most recent designation of ANSI/UL 746B as an American National Standard (ANSI) occurred on July 15, 2014. ANSI approval
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15、 should be altered in any way. All of ULs Standards and all copyrights, ownerships, and rights regarding those Standards shall remain the sole and exclusive property of UL. COPYRIGHT 2014 UNDERWRITERS LABORATORIES INC. ANSI/UL 746B-2014UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION
16、OR DISTRIBUTION WITHOUT PERMISSION FROM UL APRIL 4, 2013 POLYMERIC MATERIALS LONG TERM PROPERTY EVALUATIONS - UL 746B 2 No Text on This PageUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL CONTENTS INTRODUCTION 1 Scope .5 2 References .5 3 Su
17、pplementary Test Procedures 5 4 Characteristics of Polymeric Materials .6 5 Use of Polymeric Materials .6 DETERMINATION OF THE RELATIVE THERMAL INDICES OF POLYMERIC MATERIALS 6 General 7 7 Relative Thermal Index Based Upon Historical Record .8 8 Relative Thermal Index Based Upon Long-Term Thermal-Ag
18、ing Programs 10 9 Apparatus .11 9.1 Ovens .11 10 Scope of Test Programs .12 10.1 Selection of test properties 12 11 Property-Evaluation Tests 13 11.1 General .13 11.2 Choice of end-point .14 12 Sampling Programs .14 13 Selection of Oven Temperatures 15 14 Selection of Control Material .16 15 Specime
19、ns .16 16 Thermal Aging 16 17 End-of-Life .19 17.1 Primary properties 19 17.2 Secondary properties .19 18 Proof Testing .20 19 Analysis and Evaluation .21 20 Related Material Coverage of Variations in Material Composition .26 20.1 General .26 20.2 Thermoplastic materials .26 20.3 Thermosetting molde
20、d materials .31 21 Aging, Specimen, and Check-Test Schedules 32 21.1 General .32 21.2 Polypropylene .32 21.3 Coating powders .33 22 Fixed Time Sampling Method 39 22.1 General .39 22.2 Screening Procedure .39 22.3 Remainder of Fixed Time Sampling Method .40 RELATIVE THERMAL INDEX CLASS 23 Assignment
21、of Temperature Classications 40 MARKING 24 General 41 APRIL 4, 2013 POLYMERIC MATERIALS LONG TERM PROPERTY EVALUATIONS - UL 746B 3UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL SUPPLEMENT SA - FOLLOW-UP INSPECTION INSTRUCTIONS INTRODUCTION
22、SA1 Scope SA1 SA2 Glossary SA1 SA3 Responsibility of the Manufacturer .SA2 SA4 Responsibility of the Field Representative SA3 SA5 Selection of Samples for Follow-Up Testing .SA3 SA6 Follow-Up Test Program SA3 APRIL 4, 2013 POLYMERIC MATERIALS LONG TERM PROPERTY EVALUATIONS - UL 746B 4UL COPYRIGHTED
23、MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL INTRODUCTION 1 Scope 1.1 These requirements cover long-term test procedures to be used for the evaluation of materials used for parts intended for specic applications in end products. 1.2 Together with the St
24、andards mentioned in Supplementary Test Procedures, Section 3, these investigations provide data with respect to the physical, electrical, ammability, thermal, and other properties of the materials under consideration and are intended to provide guidance for the material manufacturer, the molder, th
25、e end-product manufacturer, safety engineers, and other interested parties. 2 References 2.1 Any undated reference to a code or standard appearing in the requirements of this standard shall be interpreted as referring to the latest edition of that code or standard. 3 Supplementary Test Procedures 3.
26、1 The Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances, UL 94, covers ammability of polymeric materials used for parts in devices and appliances. The Standard for Polymeric Materials Short Term Property Evaluations, UL 746A, contains short-term test proced
27、ures to be used for the evaluation of materials used for parts intended for specic applications in electrical end products. The Standard for Polymeric Materials Fabricated Parts, UL 746D, contains requirements for traceability and performance of parts molded and fabricated from polymeric materials.
28、3.2 Programs for the investigation of material part modications, such as the plating of plastics or the use of ame-retardant paints, are contained in the Standard for Polymeric Materials Use in Electrical Equipment Evaluations, UL 746C. 3.3 Data concerning the effect of various environments and cont
29、aminants upon the properties of materials can also be obtained through standard test procedures. The more commonly used procedures are briey described in the Standard for Polymeric Materials Short Term Evaluations, UL 746A. 3.4 Test procedures are provided in the Standard for Polymeric Materials Use
30、 in Electrical Equipment Evaluation, UL 746C, for the evaluation of polymeric materials in specic applications in end products. These test procedures include references to the data obtained from the standard property tests as well as other practical means of evaluation. 3.5 Requirements for material
31、s that have been modied to match the requirements of a specic application, including the use of recycled and regrind materials, the use of additives and colorants, and the blending of two or more materials, are described in the Standard for Polymeric Materials Fabricated Parts, UL 746D. APRIL 4, 201
32、3 POLYMERIC MATERIALS LONG TERM PROPERTY EVALUATIONS - UL 746B 5UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 4 Characteristics of Polymeric Materials 4.1 Polymeric materials include thermoplastic, thermosetting, and elastomeric materials.
33、 A thermoplastic material can be easily softened and resoftened by repeated heating. A thermosetting material cures by chemical reaction and, when cured, cannot be resoftened. An elastomeric material is capable of being stretched at room temperature to at least twice its length under low stress and
34、recovers to its original length when released from the stress. 4.2 Characteristics of polymeric materials that necessitate additional consideration include: a) Mold stresses b) Insulating quality c) Resistance to ignition d) Extinguishing characteristics e) Production of smoke and gases f) Mechanica
35、l Strength g) Compatibility with solvents h) Melting or distortion i) Cold ow, if under stress j) Fuel contribution k) Dimensional stability 5 Use of Polymeric Materials 5.1 The reduction to an acceptable level of the risks of electric shock, re, and personal injury from electrical equipment depends
36、 upon the selection of materials, design, and processing of parts as well as the assembly, mounting, and relative positions of these parts. 5.2 The properties needed by individual parts are dened by the function or functions of the part. An enclosure, for example, must ordinarily be designed to with
37、stand mechanical abuse. Accordingly, a material known to have substantial impact strength would normally be used although a material that has a lower impact strength, but is reinforced, might also be acceptable. 5.3 Electrical equipment of necessity employs many materials that usually have divergent
38、 properties. The ability to match the demands of the application with the characteristics of a material as well as the ability to compare the properties of one material with those of another can lead to an acceptable selection of materials. APRIL 4, 2013 POLYMERIC MATERIALS LONG TERM PROPERTY EVALUA
39、TIONS - UL 746B 6UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 5.4 The information gained from the data obtained from these tests can be used as an aid in the evaluation of electrical equipment using parts made of polymeric materials. Know
40、ledge of materials can be obtained from an analysis of data from standard tests conducted on small specimens. DETERMINATION OF THE RELATIVE THERMAL INDICES OF POLYMERIC MATERIALS 6 General 6.1 A relative thermal index of a material is an indication of the materials ability to retain a particular pro
41、perty (physical, electrical, etc.) when exposed to elevated temperatures for an extended period of time. It is a measure of the materials thermal endurance. For each material, a number of relative thermal indices can be established, each index related to a specic property and a specic thickness of t
42、he material. 6.2 In determining the relative thermal index of a material, the basic concepts to be followed are stated in the Institute of Electrical and Electronics Engineers Specications No. 1, General Principles for Temperature Limits in the Rating of Electrical Equipment; No. 98, Guide for the P
43、reparation of Test procedures for the Thermal Evaluation of Electrical Insulating Materials; No. 101, Guide for the Statistical Analysis of Thermal Life Test Data. 6.3 The relative thermal index of a material is to be based upon an evaluation of long-term thermal-aging data obtained under the progra
44、m described in Relative Thermal Index Based Upon Long-Term Thermal-Aging Programs, Section 8. Thermal indices on a generic basis have been established through knowledge of extensive eld-service records, as outlined in Relative Thermal Index Based Upon Historical Record, Section 7. Relative thermal i
45、ndices may also be established based upon a study and evaluation of the interrelationship of all of the data mentioned in Supplementary Test Procedures, Section 3, which can also be coupled with knowledge concerning the materials performance in insulating systems gained through experience or long-te
46、rm aging tests. 6.4 A comparison of the thermal-aging characteristics of one material of proven eld service at a particular temperature level with the thermal-aging characteristics of another material with no eld service history provides a means for estimating the relative thermal index level at whi
47、ch the second material might also provide acceptable eld service. 6.5 Another explanation of a relative thermal index is the maximum temperature below which a material maintains its characteristics over a reasonable period. This relative thermal index serves the very great need to evaluate materials
48、 that are exposed to heat sources in electrical products in which they are not used as part of an insulating system and in which they are not subjected to other major degradation inuences. It is to be assumed that neither excessively long nor excessively short duty cycles are involved. 6.6 To be val
49、id for use in a specic application, a relative thermal index of a material must be established by a study of the degradation rates of all properties that are relied upon in that application. As a corollary to this principle, more than one relative thermal index can be assigned to a material depending on the relative degradation rates of the properties of the material and depending on which of these properties are considered in establishing the indices. APRIL 4, 2013 POLYM
