Introduction
Health and Safety
This document is not intended to solve all safety problems related to its use. When using this document, users are responsible for establishing appropriate health and safety rules to ensure the applicability of this document.
The mineral oil involved in this document should be well protected. Direct contact with eyes may cause slight pain. In case of contact with eyes, large quantities of clean and flowing water can be used to wash eyes and seek medical advice in time.
Some tests involved in this document may lead to hazardous situations. Please refer to the relevant guidance documents. Environment This document will cover mineral oils, chemicals and used sample containers. Relevant disposal should avoid environmental impact, and various preventive measures should be taken to prevent mineral pollution.
The acid value measurement standards for insulating liquids are widely used in the R&D, production, quality inspection, sales, acceptance and technical exchange of insulating liquid products. The formulation of this series of standards can guide the industry to more effectively carry out the detection and evaluation of the acid value of insulating liquids, and can improve the quality and application reliability of insulating liquid products.
The acid value measurement standards for insulating liquids are prepared in different parts. In order to maintain the basic consistency with the preparation methods of corresponding IEC standards, different parts shall be listed separately when preparing this series of documents.
GB/T 41633 describes the standard method for the determination of acid value of insulating liquids. The following parts are proposed:
——Part 1: Automatic potentiometric titration. The purpose is to determine the method and step of measuring the acid value of insulating liquid by automatic potentiometric titration.
——Part 2: Colorimetric titration. The purpose is to determine the method and step of determining the acid value of insulating liquid by colorimetric titration.
——Part 3: Test methods for non mineral insulating oils Determination of unused and used non mineral insulating oleic acids for electrical purposes
Two test methods of the value; Automatic potentiometric titration and colorimetric titration.
1 Scope
This document describes two test methods for acid value of unused and used non mineral insulating oil for electrical purposes: potentiometric titration and colorimetric titration.
Note 1: In unused and used non mineral insulating oils for electrical purposes, acidic components include organic acids, phenolic compounds, oxidation products, resins, organic metal salts and additives
This document can be used to indicate the relative changes of non mineral insulating oil for electrical purposes during use under oxidation conditions, regardless of whether its chromaticity or other characteristics have changed.
Acid value can be used for quality control of unused non mineral insulating oil for electrical purposes. The oxidation products existing in the used non mineral insulating oil for electrical purposes will affect its acid value, and these oxidation products have large differences in corrosion characteristics, so this document cannot be used to predict the corrosivity of non mineral insulating oil for electrical purposes in use.
Note 2: The acid value results measured by potentiometric titration and colorimetric titration may be the same or different in value, but they are usually in the same order of magnitude.
2 Normative References
The contents in the following documents constitute indispensable provisions of this document through the normative A in the text. Where, for dated references, only the version corresponding to that date applies to this document; For undated references, the latest version (including all amendments) is applicable to this document.
ISO 5725 (all parts) Accuracy (trueness and pre precision) of measurement methods and results
Note: GB/T 6379 (all parts) Accuracy (correctness and precision) of measurement methods and results [ISO 5725 (all parts)]
ISO 6619 Petroleum products and lubricants - Neu titration number - Potentiometric titration method
IEC 60475 Method of sampling insulating liquids Note: GB/T41146-2021 Sampling methods for insulating liquids (IEC 60475:2011, IDT)
3 Terms and definitions
The following terms and definitions apply to this document.
three point one
Acid value
The amount of alkali required for titration to the end point after dissolving the sample in the specified solvent by potentiometric titration or colorimetric titration, expressed by the mass fraction of potassium hydroxide in the sample.
Note: See Appendix A for the acid value of non mineral insulating oil determined by photometric titration
4 Method A: Automatic potentiometric titration
4.1 Principle
Any acid-base titration can be carried out by potentiometry. Dissolve the insulating oil sample in the solvent, use the glass indicator electrode and reference electrode, and use potassium hydroxide isopropanol solution for potentiometric titration. The potential difference (which can be expressed by pH value after calibration) is measured after continuous addition of a known amount of potassium hydroxide isopropanol solution.
The apparent inflection point detected from the first derivative of the titration curve should be considered as the end point. If there is only a weak inflection point, the potential difference corresponding to pH 11.5 is more reproducible and less instrument dependent.
4.2 Reagents and auxiliary materials
5 Method B: Colorimetric titration
5.1 Principle
Dissolve the insulating oil sample in the specified solvent, use alkaline blue 6B as the indicator, and titrate it with potassium hydroxide isopropanol solution to the specified color.
Note: Colorimetric titration may not be applicable to dark insulating oil.
5.2 Reagents
5.2.1 General
The reagent shall be the certified analytical reagent, and the test water shall be deionized water or water of the same purity.
5.2.2 Titration reagent
0.01 mol/L and 0.05 mol/L potassium hydroxide isopropanol standard solutions are used as titration reagents for the test.
Appendix A (informative) Determination of Acid Number of Non mineral Insulating Oil by Photometric Titration
Forword
Introduction
1 Scope
2 Normative References
3 Terms and definitions
4 Method A: Automatic potentiometric titration
5 Method B: Colorimetric titration
Appendix A (informative) Determination of Acid Number of Non mineral Insulating Oil by Photometric Titration
Introduction
Health and Safety
This document is not intended to solve all safety problems related to its use. When using this document, users are responsible for establishing appropriate health and safety rules to ensure the applicability of this document.
The mineral oil involved in this document should be well protected. Direct contact with eyes may cause slight pain. In case of contact with eyes, large quantities of clean and flowing water can be used to wash eyes and seek medical advice in time.
Some tests involved in this document may lead to hazardous situations. Please refer to the relevant guidance documents. Environment This document will cover mineral oils, chemicals and used sample containers. Relevant disposal should avoid environmental impact, and various preventive measures should be taken to prevent mineral pollution.
The acid value measurement standards for insulating liquids are widely used in the R&D, production, quality inspection, sales, acceptance and technical exchange of insulating liquid products. The formulation of this series of standards can guide the industry to more effectively carry out the detection and evaluation of the acid value of insulating liquids, and can improve the quality and application reliability of insulating liquid products.
The acid value measurement standards for insulating liquids are prepared in different parts. In order to maintain the basic consistency with the preparation methods of corresponding IEC standards, different parts shall be listed separately when preparing this series of documents.
GB/T 41633 describes the standard method for the determination of acid value of insulating liquids. The following parts are proposed:
——Part 1: Automatic potentiometric titration. The purpose is to determine the method and step of measuring the acid value of insulating liquid by automatic potentiometric titration.
——Part 2: Colorimetric titration. The purpose is to determine the method and step of determining the acid value of insulating liquid by colorimetric titration.
——Part 3: Test methods for non mineral insulating oils Determination of unused and used non mineral insulating oleic acids for electrical purposes
Two test methods of the value; Automatic potentiometric titration and colorimetric titration.
1 Scope
This document describes two test methods for acid value of unused and used non mineral insulating oil for electrical purposes: potentiometric titration and colorimetric titration.
Note 1: In unused and used non mineral insulating oils for electrical purposes, acidic components include organic acids, phenolic compounds, oxidation products, resins, organic metal salts and additives
This document can be used to indicate the relative changes of non mineral insulating oil for electrical purposes during use under oxidation conditions, regardless of whether its chromaticity or other characteristics have changed.
Acid value can be used for quality control of unused non mineral insulating oil for electrical purposes. The oxidation products existing in the used non mineral insulating oil for electrical purposes will affect its acid value, and these oxidation products have large differences in corrosion characteristics, so this document cannot be used to predict the corrosivity of non mineral insulating oil for electrical purposes in use.
Note 2: The acid value results measured by potentiometric titration and colorimetric titration may be the same or different in value, but they are usually in the same order of magnitude.
2 Normative References
The contents in the following documents constitute indispensable provisions of this document through the normative A in the text. Where, for dated references, only the version corresponding to that date applies to this document; For undated references, the latest version (including all amendments) is applicable to this document.
ISO 5725 (all parts) Accuracy (trueness and pre precision) of measurement methods and results
Note: GB/T 6379 (all parts) Accuracy (correctness and precision) of measurement methods and results [ISO 5725 (all parts)]
ISO 6619 Petroleum products and lubricants - Neu titration number - Potentiometric titration method
IEC 60475 Method of sampling insulating liquids Note: GB/T41146-2021 Sampling methods for insulating liquids (IEC 60475:2011, IDT)
3 Terms and definitions
The following terms and definitions apply to this document.
three point one
Acid value
The amount of alkali required for titration to the end point after dissolving the sample in the specified solvent by potentiometric titration or colorimetric titration, expressed by the mass fraction of potassium hydroxide in the sample.
Note: See Appendix A for the acid value of non mineral insulating oil determined by photometric titration
4 Method A: Automatic potentiometric titration
4.1 Principle
Any acid-base titration can be carried out by potentiometry. Dissolve the insulating oil sample in the solvent, use the glass indicator electrode and reference electrode, and use potassium hydroxide isopropanol solution for potentiometric titration. The potential difference (which can be expressed by pH value after calibration) is measured after continuous addition of a known amount of potassium hydroxide isopropanol solution.
The apparent inflection point detected from the first derivative of the titration curve should be considered as the end point. If there is only a weak inflection point, the potential difference corresponding to pH 11.5 is more reproducible and less instrument dependent.
4.2 Reagents and auxiliary materials
5 Method B: Colorimetric titration
5.1 Principle
Dissolve the insulating oil sample in the specified solvent, use alkaline blue 6B as the indicator, and titrate it with potassium hydroxide isopropanol solution to the specified color.
Note: Colorimetric titration may not be applicable to dark insulating oil.
5.2 Reagents
5.2.1 General
The reagent shall be the certified analytical reagent, and the test water shall be deionized water or water of the same purity.
5.2.2 Titration reagent
0.01 mol/L and 0.05 mol/L potassium hydroxide isopropanol standard solutions are used as titration reagents for the test.
Appendix A (informative) Determination of Acid Number of Non mineral Insulating Oil by Photometric Titration
Contents of GB/T 41633.3-2022
Forword
Introduction
1 Scope
2 Normative References
3 Terms and definitions
4 Method A: Automatic potentiometric titration
5 Method B: Colorimetric titration
Appendix A (informative) Determination of Acid Number of Non mineral Insulating Oil by Photometric Titration
