SH/T 0731-2004 Determination of Evaporation Loss of Lubricating Oils (Thermogravimetric Noack Method)

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Card type: Test method

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

• Standard number: SH/T 0731-2004
• Chinese title: Determination of Evaporation Loss of Lubricating Oils (Thermogravimetric Noack Method)
• English title: Standard test method for evaporation loss of lubricating oils by thermogravimetric analyzer (TGA) Noack method
• Supersession relationship: not provided in the available source (the foreword only states modified adoption of ASTM D6375-99a, and does not mention superseding an old edition number)
• Adoption relationship: modified adoption of ASTM D6375-99a "Determination of Evaporation Loss of Lubricating Oils (Thermogravimetric Noack Method)", redrafted according to ASTM D6375-99a
• Publication/implementation: published by 2004-04-09, implemented by 2004-09-01
• Proposing/administrative authority: proposed by China Petroleum & Chemical Corporation; administratively controlled by the Research Institute of Petroleum Processing, China Petroleum & Chemical Corporation
• Drafting organization: Lubricant Research and Development Center, PetroChina Company Limited
• Main drafter: Lu Qinying

2. Scope of application and non-applicability

• 1.1 is applicable to the determination of base oils and additive-containing lubricating oils with a Noack evaporation loss of 0%~30%.
• Compared with the standard Noack method using Wood's alloy, this method requires a smaller sample amount and is faster and safer when continuously analyzing multiple samples.
• 1.2 The evaporation loss results determined by this standard are the same as those determined by the standard Noack method.
• 1.3 uses the International System of Units [SI] units.
• 1.4 This standard does not address all safety issues associated with its use; users should establish appropriate safety and protective measures before use and formulate corresponding management systems.
• Non-applicable scope: not provided in the available source.

3. Method principle

Place the lubricating oil sample on the sample pan of a suitable thermogravimetric analyzer (TGA), place the sample pan on the sample holder, and rapidly heat to 247~249°C in an air flow, then hold at constant temperature for a period of time. Throughout the process, the thermogravimetric analyzer monitors and records the mass lost by the sample due to evaporation. The thermogravimetric Noack evaporation loss is the mass loss fraction corresponding to the Noack reference time determined for the sample under the same thermogravimetric conditions on the subsequently determined curve of sample mass loss fraction versus time (thermogravimetric curve). (Chapter 4)

4. Reagents and materials (purity / preparation)

• 7.1 Temperature calibration standard: select the standard according to the specific thermogravimetric analyzer equipment and its characteristics; the thermogravimetric analyzer manufacturer usually provides this standard and describes its use in the operation manual.
• 7.2 Compressed air: the compressed air required for the operation of the thermogravimetric analyzer; if it may cause contamination inside the thermogravimetric analyzer, purified air shall be used.
• 7.3 Noack reference oil: an oil provided by the manufacturer and having a known Noack evaporation loss.
• Purity and specific preparation method: not provided in the available source.

5. Apparatus and equipment

• 6.1 Thermogravimetric analyzer (TGA): having all conditions required to meet the needs of this test method, and the necessary software to complete the required analysis.
  • Note: A thermogravimetric analyzer with a temperature control accuracy of less than 0.5°C should be selected.
• 6.2 Aluminum sample pan: cylindrical, with a ratio of inner diameter to height of not less than 0.45, and a volume of 50µL±3µL. If the sample pan provided by the manufacturer does not meet these criteria, a suitable sample pan may be selected and made to fit the sample holder of the thermogravimetric analyzer. The improved sample pan is shown in Figure 1.
• 6.3 Pressure regulator: capable of providing the air pressure required by the thermogravimetric analyzer.
• 6.4 Flowmeter: capable of controlling and measuring the air flow through the thermogravimetric analyzer.
• Other auxiliary utensils: caliper (see 9.1.1, used to measure the inner diameter of the sample pan).

6. Recommended operating conditions

• Heating temperature: rapidly heat to 247~249°C in an air flow, and hold at constant temperature for a period of time (Chapter 4).
• Temperature program (9.3.2): heat the sample from 50°C to the final sample temperature determined at 9.3.1, with a heating rate similar to that of the standard Noack method (100°C/min heated to 220°C, and heated from 220°C to 249°C at a rate of 10°C/min); maintain the maximum temperature 30min.
  • Note: After determining the Noack reference oil and establishing the instrument's Noack reference time (see clause 9.4), adjust the constant-temperature time of 30min; the constant-temperature time may be set to be 2min longer than the measured Noack reference time.
• 9.3.1 Temperature calibration: calibrate the temperature using the method of clause 8.1; the determined final program temperature is required to include the final sample temperature 249°C.
• 9.3.7 When the sample temperature does not exceed 249°C: when the Noack reference time is less than 7min, return to 9.3.2 and reduce the heating rate to extend the Noack reference time beyond 7min; check the sample temperature within the Noack reference time and ensure that its temperature is between 248~249°C; when the temperature is lower than 248°C, determine the difference between its temperature and 248.5°C, and use this difference to increase the set program termination temperature.
• 9.4.7 Check whether the sample temperature within the Noack reference time is between 247~249°C.
• 9.5.2 Check whether the sample temperature within the Noack reference time is between 247~250°C.
• Air flow rate: set according to the thermogravimetric analyzer manufacturer's recommendation; if condensation of the Noack reference oil occurs in any part of the thermogravimetric analyzer's balance section and furnace at the beginning of the test, the flow rate may be increased, and clause 8.1 (9.2) shall be repeated at the new flow rate.
• Combustion purge conditions (8.2): air flow 200–500mL/min, raise the temperature to at least 800°C high temperature, and maintain until no smoke is discharged from the air exhaust pipe; usually 15–20min can remove most deposits.
• Example of heating rate given in Figure 2 (source-text extraction doubtful point, requires confirmation against the source standard):
  • Heating rate of the standard Noack method sample;
  • 50°C to 235°C at 80°C/min + 235°C to 249°C at 5°C/min;
  • 50°C to 240°C at 80°C/min + 240°C to 249°C at 5°C/min;
  • 50°C to 240°C at 200°C/min + 240°C to 249°C at 5°C/min;
  • 50°C to 251°C at 200°C/min;
  • 50°C to 244.5°C at 200°C/min.
• Example of eliminating sample overtemperature in Figure 3 (source-text extraction doubtful point, requires confirmation against the source standard):
  • Heating rate of the standard Noack method sample;
  • 50°C to 249°C at 120°C/min;
  • 50°C to 235°C at 80°C/min + 235°C to 249°C at 5°C/min.

7. Sampling and sample preparation

• 9.1 Determine the sample mass:
  • 9.1.1 Measure the inner diameters of 10 different sample pans, and take their average value as the nominal inner diameter of the sample pan (cm); a caliper shall be used for the measurement.
  • 9.1.2 Calculate the required sample mass M₀ using formula (1), to the nearest 1mg:
    • M₀ = 350(ID)² ………………(1)
    • Where: M₀—sample mass, mg; ID— nominal inner diameter of the sample pan, cm (to the nearest 0.1cm).
• 9.4.4 Add the required mass of Noack reference oil (determined in clause 9.1) into a clean sample pan of known mass; whether the sample is added by volume or by mass, the error between the actual sample mass and the calculated mass shall not exceed ±3mg, and the sample mass shall be adjusted to meet this requirement.
• 9.3.4 Add the required mass ±3mg (see clause 9.1) of Noack reference oil into a clean sample pan of known mass.
• Other sampling requirements: not provided in the available source.

8. Analytical procedure

• 8 Preparation and calibration of the thermogravimetric analyzer (Note: this operation is required only when the instrument has been idle for a long time, has undergone major repair, has been operated incorrectly, or has had a change in placement location):
  • 8.1 According to the thermogravimetric analyzer manufacturer's recommendation or ASTM E1582, verify the correlation between the actual temperature and its corresponding set temperature; the temperature range of the temperature calibration standard shall include 250°C; if necessary, recalibrate and establish the correlation between actual temperature and set temperature.
  • 8.2 If necessary, remove any condensed liquid or deposits formed on the inner surfaces of the thermogravimetric analyzer by combustion; usually combustion is completed by raising the thermogravimetric analyzer to a high temperature of at least 800°C under an air flow of 200–500mL/min, and maintaining this condition until no smoke is discharged from the air exhaust pipe; usually under these conditions 15–20min can remove most deposits.
    • Warning: During this operation, do not place a sample pan in the thermogravimetric analyzer; it will melt and damage the balance or furnace.
  • 8.3 Follow the procedures and recommendations provided by the manufacturer to check the thermogravimetric analyzer balance and adjust it if necessary.
• 9.3 Temperature program (Note: this part is required only during the initial setup of the thermogravimetric analyzer):
  • 9.3.1 Use the method of clause 8.1 to calibrate the temperature; the determined final program temperature is required to include the final sample temperature 249°C.
  • 9.3.2 Set the thermogravimetric analyzer temperature program (see Section 6 Recommended operating conditions).
  • 9.3.3 Weigh the mass of the empty sample pan according to the thermogravimetric analyzer operation manual.
  • 9.3.4 Add the required mass ±3mg (see clause 9.1) of Noack reference oil into a clean sample pan of known mass.
  • 9.3.5 Place the sample pan on the sample holder and run under the temperature program of 9.3.2.
  • 9.3.6 Using the data obtained in the temperature program of 9.3.5, plot time versus sample temperature; check whether the sample temperature exceeds 249°C at any time; when the sample temperature is higher than 249°C, perform step 9.3.8; when the sample temperature does not exceed 249°C, perform step 9.3.7.
  • 9.3.7 The sample temperature does not exceed 249°C: determine the Noack reference time according to 9.4.6; when the Noack reference time is less than 7min, return to 9.3.2 and reduce the heating rate to extend the Noack reference time beyond 7min; check the temperature of the sample within the Noack reference time and ensure that its temperature is between 248 and 249°C; when the temperature is below 248°C, determine the difference between its temperature and 248.5°C, and use this difference to increase the set program termination temperature; operate according to clause 9.4.
  • 9.3.8 The sample temperature is higher than 249°C: modify the thermogravimetric analyzer temperature program to eliminate the temperature excess; this is usually done in two parts, reducing the heating rate, lowering the final program temperature, or a combination of both; an example of eliminating sample overtemperature is shown in Figure 3; repeat steps 9.3.3 to 9.3.6 until a suitable temperature program is established.
• 9.4 Determine the Noack reference time (Note: it is important to complete this determination every day before evaluating samples):
  • 9.4.1 Set the air flow rate according to clause 9.2.
  • 9.4.2 Enter the final temperature program established in clause 9.3.
  • 9.4.3 Weigh the mass of the empty sample pan according to the thermogravimetric analyzer operation manual.
  • 9.4.4 Add the required mass of Noack reference oil (determined in clause 9.1) into a known-mass empty sample pan; whether the sample is added by volume or by mass, the error between the actual sample mass and the calculated mass must not exceed ±3mg, adjust the sample mass to meet this requirement.
  • 9.4.5 Place the sample pan on the sample holder and heat the sample according to the temperature program.
  • 9.4.6 Determine from the thermogravimetric curve obtained by the temperature program in 9.4.5 the time required for the Noack reference oil to reach the Noack evaporation loss (if possible, accurate to 0.01min); this is the Noack reference time; record this time, and determine the Noack evaporation loss of the lubricating oil according to the procedure in clause 9.5; an example of the thermogravimetric curve of the Noack reference oil and how to use this curve to determine the Noack reference time is listed in Figure 4 (curve 1); the constant temperature time of the thermogravimetric analyzer temperature program can now be modified to the Noack reference time plus 2min, which will shorten the subsequent test time.
  • 9.4.7 Check whether the temperature of the sample within the Noack reference time is between 247 and 249°C; when the temperature is out of range, burn the thermogravimetric analyzer clean according to clause 8.2 and repeat the steps in clause 9.4.
  • 9.4.8 Compare the Noack reference time determined this time with those determined previously; when the difference exceeds 10%, check the operation of the thermogravimetric analyzer according to Chapter 8; when the thermogravimetric analyzer undergoes major repair or parts replacement (for example, the thermogravimetric analyzer had balance equipment, temperature sensor and similar replacements after the last Noack reference time measurement), this test method requires repeating the test starting from Chapter 8.
• 9.5 Determine the Noack evaporation loss of the sample using the thermogravimetric analyzer:
  • 9.5.1 Repeat steps 9.4.1 to 9.4.5 using the sample instead of the Noack reference oil in a new sample pan.
  • 9.5.2 Using the thermogravimetric curve of the sample and the Noack reference time determined in 9.4.6, determine the mass loss of the sample at the Noack reference time (%); this is the Noack evaporation loss determined by the thermogravimetric analyzer; an example of how to determine the Noack evaporation loss of a sample using the thermogravimetric analyzer is shown in Figure 4 (curve 2 and curve 3); check whether the temperature of the sample within the Noack reference time is between 247 and 250°C; when the temperature is not in this range, restart the test from Chapter 8.
  • 9.5.3 The thermogravimetric analyzer should be burned clean regularly (see clause 8.2); use whether the difference between successive determinations of the Noack reference time of the Noack reference oil by the thermogravimetric analyzer is greater than 10% as the criterion for evaluating the number of times the Noack reference oil can be continuously determined by the thermogravimetric analyzer between each burn; increasing the air flow rate may increase the number of tests allowed between each burn (see clause 9.2).

9. Qualitative and Quantitative and Calculation Formulas

• Calculation of sample mass (9.1.2):
  • M₀ = 350(ID)² ………………(1)
  • Where: M₀—sample mass, mg; ID— nominal inner diameter of the sample pan, cm (accurate to 0.1cm).
• Quantitative result: the thermogravimetric Noack evaporation loss is the mass loss of the sample at the Noack reference time (%), expressed as mass fraction (%) (3.3, 9.5.2).
• Repeatability (r) (11.1.1):
  • r = 0.31(X)^0.6 ………………(2)
  • Where: X— average of two determination results, %.
• Reproducibility (R) (11.1.2):
  • R = 0.39(X)^0.6 ………………(3)
  • Where: X— average of two determination results, %.
• Note: In formula (2) and formula (3), the exponent part source-text extraction is shown as "90." "0:6", suspected to be 0.6, requires confirmation against the source standard (source-text extraction).

10. Precision

• This precision and bias were determined by statistical tests of nine laboratories on eight oils from five different suppliers (Chapter 11).
• 11.1.1 Repeatability (r): the difference between two determination results obtained by the same operator using the same instrument under the same operating conditions on the same sample shall not exceed the result calculated by formula (2) (95% confidence level).
  • r = 0.31(X)^0.6 (exponent requires confirmation against the source standard (source-text extraction))
• 11.1.2 Reproducibility (R): the difference between two test results obtained by different operators using different instruments on the same sample shall not exceed the result calculated by formula (3).
  • R = 0.39(X)^0.6 (exponent requires confirmation against the source standard (source-text extraction))
• 11.2 Bias: within the repeatability of this method, there is no significant difference between the results determined by this method and the Noack evaporation loss results determined by the SH/T 0059 method.

11. Report

• 10.1 Report the thermogravimetric Noack evaporation loss result of the lubricating oil obtained in 9.5.2, accurate to 0.01%.

12. Referenced Documents

• SH/T 0059-96 Determination of Evaporation Loss of Lubricating Oils (Noack Method)
• ASTM E1582 Temperature Scale Calibration Test for Thermogravimetric Analyzer
• ASTM D6375-99a "Determination of Evaporation Loss of Lubricating Oils (Thermogravimetric Noack Method)" (modified adoption of the original standard)

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.

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