NB/SH/T 0811-2010 Determination of oxidation stability of unused hydrocarbon insulating oils

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Card type: Test method

1. Method number / full title / English title / replacement relationship

• Standard number: NB/SH/T 0811—2010 (the original cover source-text extraction reads "NB／SH／T∞11—_2010", the body page header reads "NB／SH／T 0811—2010", "NR／SH／T 081 1—2010", "NB／SⅣT 0811—2010", the standard number is based on the body page header 0811; the cover source-text extraction doubt requires confirmation against the source standard (source-text extraction))
• Chinese title: Determination of oxidation stability of unused hydrocarbon insulating oils
• English title: not provided in the available source (only the English title of the adopted international standard is given, see below)
• Adoption relationship: modified adoption of IEC 61125—1992 "Method for evaluation of oxidation stability of unused hydrocarbon insulating oils" (English version), including IEC 61125 AMD1—2004 amendment1 (MOD)
• Replacement relationship: not provided in the available source
• Publication/implementation: published on 2010-05-01, implemented on 2010-10-01; issuing authority: National Energy Administration
• Proposal/administration/drafting: proposed by China Petrochemical Corporation; administration by Sinopec Research Institute of Petroleum Processing; drafted by PetroChina Karamay Lubricant Research Institute; main drafters: Zhang Qi, Ma Shujie, Zhang Lingjun, Yu Huimin, Wang Peng, An Xiuling

2. Scope of application and exclusions

• This standard specifies a test method for determining the oxidation stability of unused hydrocarbon insulating oils under accelerated oxidation conditions.
• Applicable to unused mineral insulating oils, both uninhibited and inhibited.
• Not applicable: not provided in the available source.
• Adoption scope note: This standard only adopts the relevant content of method IEC 61125—1992 C, and does not include the content of method A and method B.

3. Method principle

A solid copper catalyst is placed in the sample to be tested, air is passed in at a constant rate, and after maintaining at a temperature of 120 ℃ for a certain time, the antioxidant capacity is evaluated by measuring the volatile acid value, oil-soluble acid value, and sediment content of the oxidized oil.

4. Reagents and materials (purity / preparation)

4.1 Reagents

• 5.1.1 n-Heptane: analytical grade.
• 5.1.2 Ethanol (95%): analytical grade.
• 5.1.3 Alkali blue 6B indicator: every 100 mL ethanol (95%) contains 2 g alkali blue 6B. Preparation: weigh alkali blue 2 g, add to 100 mL boiling ethanol (95%), reflux in a water bath for 1 h, cool and filter. If necessary, neutralize the boiled clear filtrate with 0.1 mol/L hydrochloric acid solution until adding 1 drops to 2 drops of alkali solution can change the indicator solution from blue to light red and restore to blue after cooling. (The original text "contains 29 alkali blue 6B" and "weigh alkali blue 29" are suspected to be "2 g" source-text extraction noise, requires confirmation against the source standard (source-text extraction))
• 5.1.4 Phenolphthalein indicator: every 100 mL ethanol (95%) contains 1 g phenolphthalein indicator. (The original text "contains 19 phenolphthalein" is suspected to be "1 g" source-text extraction noise, requires confirmation against the source standard (source-text extraction))
• 5.1.5 Titration solvent: toluene and ethanol (95%) mixed in 3∶2 (volume ratio).
• 5.1.6 Potassium hydroxide-ethanol solution: 0.1 mol/L ethanol solution.
• 5.1.7 Oxidation gas: air.
• 5.1.8 Hydrochloric acid: 0.1 mol/L aqueous solution.
• 5.1.9 Chloroform: analytical grade.
• 5.1.10 Acetone: analytical grade.

4.2 Materials

• 5.2.1 Catalyst: soft electrolytic copper wire, diameter approximately 1 mm～2 mm.
• 5.2.2 Abrasive cloth: 220 grade silicon carbide abrasive cloth (conforming to GB/T 2480).

5. Apparatus and equipment

• 4.1 Heating equipment
  • 4.1.1 Use a thermostatically controlled aluminum alloy heater or oil bath to maintain the insulating oil in the oxidation tube at 120 ℃±0.5 ℃ (see Figure 1 and Figure 2). Fill the oxidation tube with oil and immerse the thermometer so that the thermometer is within 5 mm from the inner bottom of the oxidation tube, then place it in the heating bath and read the temperature.
  • 4.1.2 The temperature of the upper surface of the top insulation layer is measured with a thermometer in the temperature measuring hole. The surface of the temperature measuring aluminum block, except for the surface in direct contact, is protected with suitable insulation material, and the performance of the insulation material should be suitable to meet the specified requirements. (This paragraph in the original text source-text extraction is severely incomplete, specific dimensions/requirements require confirmation against the source standard (source-text extraction))
  • 4.1.3 The diameter of the central hole of the heating part should be at least 125 mm, and... (original text incomplete, requires confirmation against the source standard (source-text extraction))
  • 4.1.4 For... (original text incomplete, requires confirmation against the source standard (source-text extraction))
  • Note: When using heating... (original text incomplete, requires confirmation against the source standard (source-text extraction))
• 4.2 Oxidation tube: made of heat-resistant glass, with a ground joint of diameter 4/29 mm, dimensions see Table 1 and Figure 4.
  • Table 1 Oxidation tube dimensions (unit: mm): total length of oxidation tube outer tube, wall thickness of oxidation tube outer tube, outer diameter of oxidation tube gas inlet tube, ... diameter 26±0.5, gas inlet tube wall thickness 0.8±0...., oxidation tube has ... and water ... axis at 60°... (the original Table 1 source-text extraction is severely incomplete, most values require confirmation against the source standard (source-text extraction))
• 4.9 Gas purification and flow control (original numbering starts from 4.9, source-text extraction incomplete):
  • 4.9.1 Gas is supplied by compressor... (original text incomplete, requires confirmation against the source standard (source-text extraction))
  • 4.9.2 The dried gas... enters a wash bottle containing concentrated sulfuric acid for drying, then passes into a bottle containing... glass wool and alkali... (original text incomplete, requires confirmation against the source standard (source-text extraction))
  • 4.9.3 The gas flow rate can be controlled by a soap bubble flow meter or... flow control, the system is equipped with... valves, each equipped with a precise needle valve... (original text incomplete, requires confirmation against the source standard (source-text extraction))
• 4.11 Thermometer: meets the requirements of thermometer No. GB—59 in GB/T 514.
• 4.12 Stoppered conical flask: 500 mL.
• Figure 1 Typical 8 hole (4×2) aluminum alloy heater; Figure 2 position of heater...; Figure 4 oxidation tube...; Figure 5 soap bubble flow meter (original illustrations, specific dimensions require confirmation against the source standard (source-text extraction))

6. Recommended operating conditions

• 9.1 Sample mass: 25 g±0.1 g.
• 9.2 Oxidation gas: air.
• 9.3 Gas flow rate: 0.15 L/h±0.015 L/h.
• 9.4 Test temperature: 120 ℃±0.5 ℃.
• 9.5 Test time: 164 h. Oils with improved oxidation stability may require a longer test time; in this case, the test time may be a multiple of 168 h until significant oxidation occurs.
  • Note: For general guidance only, based on existing experience, 164 h is sufficient for evaluating uninhibited mineral insulating oils. Inhibited insulating oils require a longer test time, 500 h is suitable for most commercial oils.
• 9.6 If used to determine the induction period, the test should continue until the volatile acid value significantly exceeds 0.1 mgKOH/g.
• 9.7 Catalyst: copper wire of a certain length with a surface area of 28.6 cm²±0.3 cm² (see Chapter 7).
• 9.8 Volatile acids are absorbed by an aqueous solution containing phenolphthalein.

7. Sampling and sample preparation

• Chapter 8 Preparation of insulating oil samples: filter the sample with a pre-dried (105 ℃ at 1 h) glass filter, or use a membrane filter equipped with a 8 μm membrane to remove residual sediment, cellulose, and excess water from the sample. Discard the first 25 mL filtrate. (The original text "105% at lh" and "8 funnel m membrane" are suspected to be "105 ℃ at 1 h" and "8 μm membrane" source-text extraction noise, requires confirmation against the source standard (source-text extraction))
• Chapter 7 Catalyst preparation:
  • 7.1 Before use, polish the specified length of copper wire with 220 grade silicon carbide abrasive cloth meeting the requirements of GB/T 2480, then wipe off all polishing marks with fiber-free filter paper, and finally wipe with a dry fiber-free cloth.
  • 7.2 Wind the copper wire into a spiral with an outer diameter of 2 cm and a length of 5 cm.
  • 7.3 Immerse the copper coil in n-heptane for thorough cleaning, dry in air, and immediately place into the oxidation tube.
  • 7.4 To prevent contamination, the prepared coil should only be handled with tweezers, and the copper wire must not be reused.
• Chapter 6 Cleaning of test vessels: The test tube and absorption tube should first be cleaned with acetone, then rinsed with distilled or deionized water, drained, and soaked in concentrated sulfuric acid for at least 16 h, then rinsed with tap water until acid-free, and finally rinsed with distilled or deionized water. Place the test tube and absorption tube in an oven, maintain at 105 ℃ for at least 3 h, then place in a desiccator or drying oven to cool to room temperature for later use. (The original text "105%" is suspected to be "105 ℃" source-text extraction noise, requires confirmation against the source standard (source-text extraction))

8. Analytical procedure

• 10.1 Test preparation
  • 10.1.1 Adjust the heating equipment so that the oil sample in the oxidation tube is maintained at the required 120 ℃±0.5 ℃ (thermometer meets the requirements of GB—59 in GB/T 514).
  • 10.1.2 Weigh 25 g±0.1 g of the test sample and place it into the oxidation tube, then add the catalyst copper coil prepared as required in Chapter 7. Insert the gas inlet tube with a ground-glass stopper, place the oxidation tube into the heating apparatus, and if necessary use a O type rubber ring to seal between the oxidation tube and the insulation layer.
  • 10.1.3 Add 25 mL of distilled water into the absorption tube. Add a few drops of phenolphthalein indicator solution. Insert the gas inlet tube with a ground-glass stopper and connect the oxidation tube (see Figure 4).
  • 10.1.4 Adjust the air flow rate so that when a soap-bubble flow meter is connected to the outlet of the absorption tube, the measured flow rate is 0.15 L/h±0.015 L/h.
• 10.2 Oxidation
  • 10.2.1 Maintain the test sample temperature at 120 ℃±0.5 ℃ and the air flow rate at 0.15 L/h±0.015 L/h, and carry out oxidation.
  • 10.2.2 Check the air flow rate and temperature daily.
  • 10.2.3 If the induction period is to be measured, select appropriate time intervals and determine the volatile acids by titrating the aqueous solution in the absorption tube. According to the oxidation rate of the sample to be tested, ... (the source text is incomplete; requires confirmation against the source standard (source-text extraction))
• 10.3 Determination of oxidized oil
  • 10.3.1 Formation of sediment (this section in the source text is source-text extraction severely incomplete; only scattered text is visible: sediment collection should be strictly in accordance with ...; place the oxidized ...; use 300 mL ...; place the last ...; already constant weight ...; 24 h or 48 h time interval (at the end select 72 h) ...; place the oxidation tube in a dark place ...; use ... to wash off the material adhering to the oxidation tube, copper coil ...; ... in a stoppered conical flask containing the sample; ... then the sample ...; ... into ... the insulation on the wax ... in a stoppered conical flask; ... until no oil traces remain, and ... allow to stand in a dark place at 20 ℃±5 ℃ for 24 h, then ... . The specific procedure requires confirmation against the source standard (source-text extraction))
  • 10.3.3 Volatile acids: ... titrate by the method ... (this section in the source text is source-text extraction severely incomplete; only scattered text is visible: 10.3.3.1, 10.3.3.2, 10.3.3.3, 10.3.3.4; place the titration ...; calculate the ... consumed per gram of insulating oil ...; ... reconnect the tube; ... calculate each volatile ... from the number of milliliters; directly titrate ... . The specific procedure requires confirmation against the source standard (source-text extraction))
  • 10.3.4 Total acid value: ... (this section in the source text is source-text extraction severely incomplete; only scattered text is visible: total acid value, or ...; place ...; 20% ...; ... sum, calculated by formula (3) ...; ... expressed as milligrams of potassium hydroxide, by formula (4) ... . The specific procedure requires confirmation against the source standard (source-text extraction))

9. Qualitative and quantitative determination and calculation formulas

• Calculation of volatile acid value: expressed as the number of milligrams of potassium hydroxide consumed per gram of insulating oil, calculated according to formula (2) (the source formula (2) source-text extraction is incomplete; only symbols are visible: ... D ... concentration of potassium hydroxide ethanol solution ...; G—— mass of the test sample, g. The complete formula requires confirmation against the source standard (source-text extraction))
• Total volatile acid value: ... is ... (the source text is incomplete; requires confirmation against the source standard (source-text extraction))
• Total acid value: expressed as ... milligrams of potassium hydroxide, calculated by formula (4) (the source formula (4) source-text extraction is incomplete; only scattered text is visible: ... includes the following content ...; ... method; ... (3), precision ...; ... accurate to 0 ...; ... consumption factor, precision ...; k accurate to 1 ... . The complete formula requires confirmation against the source standard (source-text extraction))
• Note: without added inhibitor ... the curve may give ... the precision ... induction period ... value may be for uninhibited mineral insulating ... the precision ... and oxidation rate ... sudden change ... occurs ... the difference between the volatile acid value and ... should not be greater than the value specified in Table 2. (This note in the source text is source-text extraction severely incomplete; requires confirmation against the source standard (source-text extraction))

10. Precision

• 12.1 Repeatability (r): the difference between test results obtained by the same operator using the same apparatus on the same test sample ... should not be greater than the value specified in Table 2. (The source text is incomplete; for specific values see Table 2; Table 2 source-text extraction is not provided in the available source; requires confirmation against the source standard (source-text extraction))
• 12.2 Reproducibility (R): different operators in different laboratories ... specified value. (The source text is incomplete; for specific values see Table 2; Table 2 source-text extraction is not provided in the available source; requires confirmation against the source standard (source-text extraction))
• Note: The result of each laboratory refers to the average of two results conforming to clause 12.1 (repeatability).
• The specific content of Table 2 is not provided in the available source (source-text extraction missing); requires confirmation against the source standard (source-text extraction).

11. Report

Not provided in the available source (the content of Chapter 11 of the main text is source-text extraction missing; requires confirmation against the source standard (source-text extraction)).

12. Normative references

• GB/T 514 Specification for glass liquid thermometers for petroleum product testing
• GB/T 2480 Ordinary abrasive silicon carbide
• GB/T 5654 Measurement of power-frequency relative permittivity, dielectric dissipation factor and volume resistivity of liquid insulating materials
• IEC 61125—1992 Method for evaluating the oxidation stability of unused hydrocarbon insulating oils (including IEC 61125 AMD1—2004 amendment 1)
• Note: Annex B in the comparison table mentions IEC 60628—1985 (original note: other clause numbers of this standard outside those in the table and the clause numbers of IEC 60628—1985 are all the same and their contents correspond)

13. Source and verification

This page is an AI translation of the available Chinese method card. Human verification is pending. It is not an official translation of the standard. Check the source standard and product certificate before use.

14. Quick reference for questions and answers