SH/T 0618-1995 Determination of dynamic viscosity of lubricating oils under high shear conditions (Ravenfield method)

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Card type: Test method

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

• Standard number: SH/T 0618-95 (confirmed in 2004)
• Chinese full name: Determination of dynamic viscosity of lubricating oils under high shear conditions (Ravenfield method)
• English name: not provided in the available source
• Replacement relationship: not provided in the available source
• Adoption relationship: equivalent adoption of the European Coordination Committee (CEC) standard method L-36-T-84 "Determination of dynamic viscosity of lubricating oils under high shear conditions (Ravenfield method)"
• Approval/implementation: approved by China Petrochemical Corporation 1995-06-15, implemented on 1995-10-01
• Technical custody/drafting: technical custody and responsible drafting by the Research Institute of Petroleum Processing; main drafter Lü Zhihua

2. Scope of application and non-applicability

• This standard specifies the method for determining the dynamic viscosity of lubricating oils under high shear conditions.
• This standard applies to lubricating oils.
• Not applicable: not provided in the available source.

3. Method principle

Add the sample between the rotor and stator in the fixed spherical sleeve. The rotor and stator are fitted with a cone, and the gap between them can be adjusted to adjust the shear rate. The rotor rotates at a known rate, and the resulting torque value is measured. From the torque value, the dynamic viscosity of the sample is found from a standard curve obtained with Newtonian standard oils. The test temperature is 150 ℃, and the shear rate is 10⁶ s⁻¹.

4. Reagents and materials (purity / preparation)

• Petroleum ether: analytical grade, 60～90 ℃. Note: the solvent is relatively light; pay attention to safety.
• Newtonian standard oil: CEC reference oil RL102-81107.
• Non-Newtonian check oil: CEC reference oil RL174 or check oil "B". Note: the commercial number and viscosity value of each batch of CEC check oil are different.
• Calibration weights (provided with the instrument).
• Polishing liquid (supplied with the instrument, see Appendix C).

5. Instruments and equipment

• High shear viscometer: BE type (single speed), or BS type (multi-speed).
• Calibration weights (provided with the instrument).
• Wash bottle: with metal nozzle.
• Constant-temperature oil bath: capable of maintaining the temperature at 150 ℃±0.2 ℃.
• Computer: any computer with the function of drawing standard curves and calculating torque values may be used.
• Vacuum pump.
• Dial gauge (used for reading the vertical position of the rotor, see 5.4.3, 5.4.16).
• Torque shaft radius 7 cm, weight 250 g (for full-scale electronic adjustment, see Appendix A).

6. Recommended operating conditions

• Test temperature: 150 ℃.
• Shear rate: 10⁶ s⁻¹.
• Instrument stabilization: before setting the zero point and full scale, the entire instrument except the heat bath must be turned on for at least 30 min.
• At least 3 h before the test, turn on the circuit switches of the heat bath, circulation pump and viscometer (6.1).
• Temperature setting: at the beginning, the oil bath temperature should be 1～2 ℃ higher than the test temperature; when approaching the test temperature, the rate of temperature rise per 0.1 ℃ shall be not less than 4 s (5.5.3). Note: the temperature controlled by the oil bath has a certain relationship with the viscosity of the sample and should be adjusted at any time; if the sample viscosity is relatively high, the oil bath temperature should be controlled lower, and if the sample viscosity is relatively low, the oil bath temperature should be controlled slightly higher.

7. Sampling and sample preparation

not provided in the available source.

8. Analysis procedure

8.1 Preparatory work

• Instrument stability: before setting the zero point and full scale, the entire instrument except the heat bath must be turned on for at least 30 min to reach a stable state (5.1).
• Zero point setting (5.2): remove the rotor from the motor; turn on the motor 10 s to make it run smoothly; adjust the screw marked "Z" on the indicator so that the torque meter displays zero. Note: after the rotor is inserted into the stator, the zero point must not be reset even if it shifts.
• Full-scale position setting: see Appendix A (5.3).
• Instrument calibration (5.4):
  • 5.4.1 For RL106 standard oil, use the constants on the calibration certificate to calculate the torque value at a shear rate of 1×10⁶ s⁻¹. Initially assume that the effective height of the rotor is equal to "he" (for the relevant equations, see Appendix B).
  • 5.4.2 When the system reaches the test temperature, carefully adjust the vertical position of the rotor until the top of the rotor is level with the top of the stator.
  • 5.4.3 Place the dial gauge on the support column and set its reading to zero.
  • 5.4.4 Place the upper part of the main unit on the positioning ball, then turn the handwheel so that the lifting screw is completely in a relaxed state.
  • 5.4.5 Rinse the stator several times with petroleum ether, gently turn the rotor by hand, and suck it out from the side arm.
  • 5.4.6 Inject RL106 standard oil into the measuring system from the side arm until its liquid level just covers the rotor.
  • 5.4.7 Slowly lower the positioning ball while gently turning the rotor by hand until rotation is clearly obstructed. Record the dial gauge reading.
  • 5.4.8 Raise the positioning ball so that the dial gauge pointer just turns back two revolutions.
  • 5.4.9 Turn on the motor.
  • 5.4.10 Observe the torque meter reading. After cold oil is added and the motor is started, the reading will initially rise, and as the temperature of the RL106 standard oil increases, it will gradually shift downward. If the reading changes irregularly, lower the positioning ball by 0.025～0.05 mm.
  • 5.4.11 Run the motor for 30～60 s. During this period, due to viscous heating, the temperature rises and the torque value decreases. Record the torque reading at an appropriate temperature point during this process. Then turn off the motor.
  • 5.4.12 Suck out the RL106 standard oil from the side arm and clean the sample cell thoroughly with petroleum ether.
  • 5.4.13 Inject RL106 standard oil again, turn on the motor for a few minutes. Suck it out from the side arm and inject RL106 standard oil again.
  • 5.4.14 Repeat steps 5.4.9～5.4.11. The difference between the readings obtained shall not exceed ±2.0 divisions.
  • 5.4.15 Turn the motor on again and lower the positioning ball in small increments. Observe the torque meter reading. Run the motor for about 5 min at each step, and lower the rotor in this way until the torque value calculated in 5.4.1 is reached at the set temperature. Note: a new or repaired rotor/stator pair cannot directly undergo the procedure of 5.4.15, but requires a "running-in" process.
  • 5.4.16 After reaching the specified torque reading, the torque value should be recalculated using the effective height of the rotor "he". At this time, record the dial gauge reading. Note: the dial gauge reading is expressed as "a". The conversion method for the "a" value is given in the calibration book.
  • 5.4.17 Check the degree of instrument calibration with RL106 standard oil. It should be consistent with the above.
• Temperature setting (5.5): see Section 6.
• Standard curve plotting (5.6):
  • 5.6.1 Clean the sample cell with solvent and inject standard oil. Turn on the motor for a few minutes.
  • 5.6.2 Turn off the motor and suck out the standard oil from the side arm. Inject the same standard oil into the sample cell again, just enough to cover the rotor.
  • 5.6.3 When the temperature rises to 145 ℃, check by hand whether the rotor turns freely, then turn on the motor.
  • 5.6.4 When approaching the test temperature, observe the rate of temperature rise. If it meets the requirements of 5.5.3, when the test temperature reaches 150 ℃, record the torque value at this time. If it cannot meet the requirements of 5.5.3, adjust the bath temperature and repeat the steps of 5.6.1.
  • 5.6.5 Repeat steps 5.6.2 to 5.6.4.
  • 5.6.6 If the difference between the two measured torque values is within 1% of their arithmetic mean, the average may be used to plot against the viscosity of 5.6.8. If the error does not meet the requirement, repeat the operation of 5.6.5 until the difference between the two values is within 1% of their arithmetic mean. Use their arithmetic mean as the measurement result.
  • 5.6.7 Repeat steps 5.6.1～5.6.6 for the other five standard oils.
  • 5.6.8 Plot a standard curve using the torque values of six standard oils against the viscosity values. It should be a straight line passing through the origin; regression analysis results show that its correlation coefficient should be greater than 0.99990, and the intercept should not be greater than ±2.0 g·cm. Note: when the intercept exceeds ±2.0 g·cm, it indicates that the rotor/stator are in contact with each other; in this case, the test must be stopped immediately and the rotor/stator repaired (see Appendix C).
• Severity check (5.7):
  • 5.7.1 After completing the work of clause 5.6, inject check oil "B" into the viscometer, and determine the torque according to the steps of 5.6.1～5.6.6 under the conditions of 150 ℃, 10⁶ s⁻¹.
  • 5.7.2 Find the viscosity of check oil "B" from the standard curve; this value should be 3.54 mPa·s±0.07 mPa·s. Note: the viscosity value of each batch of check oil is different; this value is provided by the supplier of the check oil.
  • 5.7.3 Observe that the dial gauge reading should be the same as 5.4.16.
• The severity check must be performed before testing every day.

8.2 Test procedure

• 6.1 At least 3 h before the test, turn on the circuit switches of the heat bath, circulation pump and viscometer.
• 6.2 When the test temperature is about to be reached, lower the rotor into the stator so that the upper part of the main unit touches the positioning ball, then continue turning the handwheel until the lifting mechanism is completely in a relaxed state. Note: the rotor must be lowered only when there is oil in the sample cell.
• 6.3 Check that the dial gauge reading should be the same as 5.7.3.
• 6.4 Clean the sample cell with petroleum ether, then inject the sample, turn on the motor for a few minutes and then turn it off.
• 6.5 Suck out the sample from the side arm and inject a new sample again.
• 6.6 According to the steps of 5.6.3～5.6.6, use the arithmetic mean of the two measured values as the torque value of the sample. Note: when the viscometer is idle for more than a few minutes, the rotor is required to be gently lifted with the handwheel. The rotor must be lifted after heating is stopped.

9. Qualitative and quantitative determination and calculation formula

• 7.1 Find the corresponding viscosity values from the calibration curve or input the torque values obtained in clause 6.6 into the computer.
• 7.2 Take the arithmetic mean of two viscosity values as the dynamic viscosity result of the sample under the conditions of 150 ℃, 10⁶ s⁻¹. Report in units of mPa·s, with the reported result accurate to two digits after the decimal point.
• Appendix B (supplementary document) dynamic viscosity of the cylindrical viscometer η (mPa·s) is calculated according to formula (B1):
  • η = τ / γ (B1)
  • Where: τ— shear stress, mPa; γ— shear rate, s⁻¹; X— torque, g·cm; A— rotor curved surface area, cm²; R— rotor radius, cm.
  • The rotor curved surface area A (cm²) is calculated according to formula (B4):
    • A = πR²[360 − 4cos⁻¹(d/a)] / 360 (B4)
    • Where: h— rotor height, cm; d— rotor diameter (see Figure B1), cm; t— rotor plane width (see Figure B1), cm.
  • Torque X (N·m) = η·γ·d²πh[360 − 4cos⁻¹(d/a)] / (7.2×10⁶) (B5)
  • Torque X (g·cm) = η·γ·d²·h[360 − 4cos⁻¹(d/a)] / (100×2×360×981) (B6)
  • For a given rotor/stator system: torque X = R₀·η·γ·he (B7)
    • Where: he— effective height of the rotor, cm; R₀—rotor constant, given in the calibration certificate.
    • R₀ = π/2 · [360 − 4cos⁻¹(d/a)] / 7.063×10⁶
  • Note: When a < (S−h), he = ha; when a > (S−h), he = S−a (see Figure B2). (S−h): given in the calibration certificate. S: stator depth (given in the calibration certificate).
  • Note: The original formulas (B2) (B3) and some symbols are severely incomplete in source-text extraction; the above formulas are organized according to the recognizable parts of the original text, the meanings of the symbols are subject to the original text, and doubtful points require confirmation against the source standard (source-text extraction).

10. Precision

Judge the reliability of the results according to the following provisions (95% confidence level).

• 8.1 Repeatability: The difference between two results obtained by the same operator in repeated determinations shall not be greater than 0.06 mPa·s.
• 8.2 Reproducibility: The difference between two results obtained by different operators in different laboratories on the same sample shall not be greater than 0.0239(X+2) mPa·s. Here (X) is the arithmetic mean of the two results under the conditions of 150 ℃, 10⁶ s⁻¹.
• Note: These precision values were obtained in the year 1984, and are statistical results obtained after tests by 7 laboratories on 7 viscosity values of oil samples in the range of 2.6～4.7 mPa·s under the conditions of 150 ℃, 10⁶ s⁻¹.
• Typical reproducibility data:

  X, mPa·s	2.5	3.0	3.5	4.0	4.5	5.0
  Reproducibility, mPa·s	0.11	0.11	0.13	0.14	0.15	0.17

11. Report

• Find the corresponding viscosity values from the torque values obtained in clause 6.6, either from the calibration curve or by entering them into a computer.
• Take the arithmetic mean of two viscosity values as the dynamic viscosity result of the sample under the conditions of 150 ℃, 10⁶ s⁻¹.
• Report in units of mPa·s, with the reported result accurate to two digits after the decimal point.

12. Normative references

Not provided in the available source.

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