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    ASTM D115 - 17

    Standard Test Methods for Testing Solvent Containing Varnishes Used for Electrical Insulation

    Active Standard ASTM D115 | Developed by Subcommittee: D09.01

    Book of Standards Volume: 10.01

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    Significance and Use

    4.1 Control—The following tests are useful for control purposes during the manufacture and use of varnishes, and for determining the uniformity of batches:

    4.1.1 Specific gravity,

    4.1.2 Viscosity,

    4.1.3 Flash point, and

    4.1.4 Nonvolatile matter by weight.

    4.2 Performance—The following tests are useful for determining the performance of varnishes during application and use:

    4.2.1 Drainage,

    4.2.2 Time of drying,

    4.2.3 Build,

    4.2.4 Dielectric strength,

    4.2.5 Thermal endurance,

    4.2.6 Varnish compatibility,

    4.2.7 Salt water proofness, and

    4.2.8 Oil resistance.

    1. Scope

    1.1 These test methods cover tests for solvent containing varnishes primarily intended to provide electrical, mechanical, and chemical protection for electrical equipment. These test methods include tests for control and performance as follows:




    38 – 42

    Dielectric Strength

    43 – 48


    26 – 32

    Flash Point

    18 – 20

    Nonvolatile Matter

    21 – 25

    Oil Resistance

    54 – 56

    Preparation of Test Specimens


    Specific Gravity

    9 – 12

    Temperature Index


    Time of Drying

    33 – 37

    Varnish Compatibility

    51 – 53


    13 – 17

    1.2 Where the entire test method is included in this standard, the precision and bias are not known unless given in the stated method.

    1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.

    1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 5.

    Note 1: There is no equivalent IEC standard.

    1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    D56 Test Method for Flash Point by Tag Closed Cup Tester

    D93 Test Methods for Flash Point by Pensky-Martens Closed Cup Tester

    D149 Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at Commercial Power Frequencies

    D202 Test Methods for Sampling and Testing Untreated Paper Used for Electrical Insulation

    D287 Test Method for API Gravity of Crude Petroleum and Petroleum Products (Hydrometer Method)

    D295 Test Methods for Varnished Cotton Fabrics Used for Electrical Insulation

    D374 Test Methods for Thickness of Solid Electrical Insulation (Metric) D0374_D0374M

    D580 Specification for Greige Woven Glass Tapes and Webbings

    D1475 Test Method for Density of Liquid Coatings, Inks, and Related Products

    D1932 Test Method for Thermal Endurance of Flexible Electrical Insulating Varnishes

    D2518 Specification for Woven Glass Fabrics for Electrical Insulation

    D2519 Test Method for Bond Strength of Electrical Insulating Varnishes by the Helical Coil Test

    D3145 Test Method for Thermal Endurance of Electrical Insulating Varnishes by the Helical Coil Method

    D3251 Test Method for Thermal Endurance Characteristics of Electrical Insulating Varnishes Applied Over Film-Insulated Magnet Wire

    D3278 Test Methods for Flash Point of Liquids by Small Scale Closed-Cup Apparatus

    D3487 Specification for Mineral Insulating Oil Used in Electrical Apparatus

    D5032 Practice for Maintaining Constant Relative Humidity by Means of Aqueous Glycerin Solutions

    D5423 Specification for Forced-Convection Laboratory Ovens for Evaluation of Electrical Insulation

    E104 Practice for Maintaining Constant Relative Humidity by Means of Aqueous Solutions

    ICS Code

    ICS Number Code 29.035.60 (Varnished fabrics)

    Referencing This Standard
    Link Here
    Link to Active (This link will always route to the current Active version of the standard.)

    DOI: 10.1520/D0115-17

    Citation Format

    ASTM D115-17, Standard Test Methods for Testing Solvent Containing Varnishes Used for Electrical Insulation, ASTM International, West Conshohocken, PA, 2017, www.astm.org

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