NB/SH/T 0852-2010 Determination of the viscosity-temperature relationship of in-service oils and soot-containing engine oils at low temperatures

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Card type: Test method

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

• Standard number: NB/SH/T 0852—2010
• Chinese full title: Determination of the viscosity-temperature relationship of in-service oils and soot-containing engine oils at low temperatures
• English name: Standard test method for determining the viscosity-temperature relationship of used and soot-containing engine oils at low temperature
• Replacement relationship: not provided in the available source (the foreword only states modified adoption of ASTM D7110-05a, and does not mention replacing any previous version of the standard)
• Adoption relationship: modified adoption of ASTM D7110-05a "Standard Test Method for the Relationship Between Viscosity and Temperature of In-Service Oils and Soot-Containing Engine Oils at Low Temperatures"
• Publication/implementation: published by 2011-01-09, implemented by 2011-05-01; issuing body: National Energy Administration
• Custodianship: Subcommittee on Lubricating Oil Drain Intervals of the National Technical Committee for Standardization of Petroleum Products and Lubricants (SAC/TC280/SC6)
• Drafting organization: PetroChina Dalian Lubricating Oil Research and Development Center

2. Scope of application and non-applicability

• 1.1 specifies a method for determining the apparent viscosity of in-service engine oils or soot-containing engine oils at low temperatures.
• 1.2 produces a shear rate of approximately 0.25 s⁻¹ when the shear stress is below 200 Pa (the source text source-text extraction reads "0.25", requires confirmation against the source standard (source-text extraction)); within the temperature range of −5 ℃ to −40 ℃, the sample is cooled at a rate of 3 ℃/h while its apparent viscosity is continuously measured.
• The results determined by 1.3 are viscosity, maximum viscosity growth rate (gel index), and gel index temperature.
• The applicability of 1.4 to petroleum products other than engine oils has not been established.
• 1.5 does not address all safety issues associated with its use; users should establish appropriate safety and protection measures and management systems before use.
• 1.6 uses International System of Units [SI] units.

3. Method principle

A special rotational viscometer with a digital output computer program is used to analyze in-service oils and soot-containing engine oils. A glass stator and a metal rotor are attached to the viscometer; according to the temperature control program for calibration and sample analysis, and according to the stator and rotor pairing used during calibration, the test lubricating oil sample 20 mL is poured into the stator. It is preheated in a 90 ℃ preheater for 1.5 h to 2.0 h. After preheating is complete, the room-temperature rotor is connected to the stator tube containing the preheated oil, and then connected to the viscosity head with a torque sensor; the viscosity head has an adapter that allows the rotor to automatically position itself at the center of the stator during the test. The rotor speed is 0.3 r/min, and the cooling program of the sample cell starts from −5 ℃ and decreases at a rate of 3 ℃/h to the temperature at which the maximum torque can be recorded. After collecting the required information, the computer program generates the required viscosity and rheological values from the recorded data.

4. Reagents and materials (purity / preparation)

• 7.1 Calibration oil: a Newtonian calibration oil with defined dynamic viscosity and viscosity index within the temperature range of −5 ℃ to −35 ℃.
• 7.2 Gel index reference oil: a GIR series non-Newtonian reference oil with known gel index and associated gel index temperature.
• 7.3 Latex sleeve: when the stator containing the sample is preheated in the heater, a latex sleeve is used to seal the opening to prevent water vapor from condensing inside the stator.
• 7.4 Viscometer head: a viscosity head equipped with torque signal output and appropriate sensitivity.
• 7.5 Program-controlled low-temperature bath.
• 7.6 Torque signal recorder: computer, analog-to-digital signal converter, data analysis program.
• 7.7 Preheater: a program-controlled or non-program-controlled sample preheating device.
• 7.8 Operator-calibrated, 90 ℃ to −20 ℃ temperature measuring device.
• 7.9 Newtonian calibration oil.
• 7.10 Dry air or nitrogen source and gas introduced into the upper part of the stator.
• 10.1.1 Ethanol coolant: the water content must not be higher than 6%, otherwise replace it with new ethanol having a water content of less than 0.5%.
• 10.1.2 Add ethanol coolant with a water content of less than 0.5% to the appropriate level in the cooling bath.

5. Instruments and equipment

• 6.1 Test cell: composed of a matched stator and rotor meeting the dimensional requirements (see Figure 1).
  • 6.1.1 Rotor dimensions: length 65.5 mm ± 0.1 mm, diameter 18.40 mm ± 0.02 mm.
  • 6.1.2 Stator dimensions: diameter 22.05 mm ± 0.02 mm, length such that throughout the entire temperature range the sample liquid level is at least 15 mm below the coolant liquid level.
• 6.2 Viscometer drive module: the rotational viscometer drive module can generate an analog signal for transmission to an analog-to-digital converter or other analog signal data processor, such as a chart recorder.
  • 6.2.1 The viscometer drive module using rotors and stators conforming to the descriptions in 6.1.1 and 6.1.2 must be capable of measuring at least 90000 mPa·s.
• 6.3 Test cell alignment device: ensures the test cell is axially vertical, so that the rotor is correctly fixed in the stator, and gives repeatable torque readings for each test when the analytical instrument is installed.
  • 6.3.1 Viscometer support: supports the viscometer so that it is axially vertical.
  • 6.3.2 Stator clamp: connected to the viscometer support to clamp and support the stator.
• 6.4 To prevent condensation and crystallization of water vapor on the sample surface, a dry atmosphere must be provided at the sample surface in some manner.
• 6.5 Program-controlled liquid cooling bath: controls the temperature at ±0.1 ℃, cools at a rate of 1 ℃/h within the selected temperature range, and can run either the calibration program or the test program.
  • 6.5.1 Temperature controller: according to the settings of the calibration program and test program, controls the temperature within 0.1 ℃ of the selected temperature.
• 6.6 Computer, analog-to-digital converter, and analysis program: receive data from the viscometer operating module and convert it into the required information.
• 6.7 Preheater: according to the program, can precisely control the temperature at 90 ℃ ± 2 ℃ and the heating time after reaching the preheating temperature.
• Figure 1 Test cell: glass stator (inner diameter 22.07 mm, length 65.5 mm), rotor (diameter 18.42 mm), stator tube scale line, operating liquid level (the dimensions in the original figure caption are inconsistent with the dimensions in the text of 6.1, requires confirmation against the source standard (source-text extraction)).

6. Recommended operating conditions

• Shear stress: below 200 Pa; shear rate: approximately 0.25 s⁻¹ (requires confirmation against the source standard (source-text extraction)).
• Temperature range: −5 ℃ to −40 ℃; cooling rate: 3 ℃/h.
• Preheating: 90 ℃ ± 2 ℃, 1.5 h to 2.0 h (Chapter 4); 12.2.2 is 90 ℃ ± 2 ℃ maintained for 90 min to 120 min.
• Rotor speed: in the uniform stage 12 r/min maintained for 10 min, in the test stage 0.3 r/min.
• Dry gas flow rate: approximately 10 mL/min (Chapter 11, 13.8); 6.4/7.10 provides dry air or nitrogen.
• Cooling bath temperature control: ±0.1 ℃; calibration/test program cooling rate 1 ℃/h (6.5).
• The temperature steps of the calibration program are shown in Table 1; the temperature steps of the test program are shown in Table 2.

Table 1 Procedure for obtaining calibration information with the liquid cooling bath (original table 1, source-text extraction is noisy, requires confirmation against the source standard (source-text extraction))

(In the original table 1, the correspondence between the text such as "cool to −5 hold/set data acquisition and start program/acquire data/cool to −10 ℃ and hold..." and the temperature column has a misalignment of source-text extraction, requires confirmation against the source standard (source-text extraction))

Table 2 Procedure for obtaining test oil information with the liquid cooling bath (original table 2, source-text extraction is noisy, requires confirmation against the source standard (source-text extraction))

7. Sampling and Specimen Preparation

• 8 Sampling: This test requires approximately 20 mL of sample; the sample must be sufficiently vibrated to ensure uniformity (see 12.1).
• 12.1 Mix the specimen thoroughly in its original container until uniform.
• 12.2 Pour the specimen into the stator up to the mark (see Figure 1) to prepare for preheating, and seal with a latex sleeve to prevent loss of volatile components or condensation of moisture.
  • 12.2.1 Place the specimen into the preheater.
  • 12.2.2 Remove from the center of the preheater and hold at a temperature of 90 ℃ ± 2 ℃ for 90 min～120 min.
• 12.3 Cool the specimen until it can be touched.
  • 12.3.1 Insert the rotor at room temperature at an angle into the matching stator to prevent bubbles from forming at the bottom of the rotor, prepare to connect it to the viscometer head support stand, and then immediately carry out the following preparation and cold bath immersion steps.
  • Note: The rotor must not be heated with the stator and specimen, as this will greatly prolong the cooling time.

8. Analytical Procedure

• 9 Instrument Preparation
  • 9.1 Using the preheater: a program-controlled preheater keeps the preheated specimen temperature constant at 90 ℃ ± 2 ℃, maintained for 1.5 h.
  • 9.2 Liquid cold bath preparation: check the liquid level of the program-controlled liquid cold bath, and according to the manufacturer's instructions, fill the cold bath to the correct depth at −5 ℃.
  • 9.3 Check the cooling program of the program-controlled cold bath; the operating steps are shown in Table 1 and Table 2.
  • 9.3 (Note) When connecting the upper hook of the rotating shaft to the rotating shaft of the viscometer drive module, handle gently and rotate slightly during tightening, otherwise the jewel-bearing inside may be damaged, and the rotating shaft may also be bent.
• 10 Test Chamber and Oil Sample Test Calibration
  • 10.1 Program-controlled liquid coolant, cooling bath.
    • 10.1.1 According to the average ambient humidity, check the water content in the ethanol coolant every 1 month(s) to 6 month(s); the water content must not be higher than 6%, otherwise replace with new ethanol having a water content less than 0.5%.
    • 10.1.2 Add ethanol coolant with a water content less than 0.5% to the appropriate position in the cooling bath. During low-temperature analysis tests, the liquid level of the ethanol coolant must be at least 15 mm above the oil level in the stator, and the low liquid level indicator light will be on.
    • 10.1.3 Use the liquid bath temperature controller to set the bath temperature to −20 ℃, allow gradual equilibration for 1 h; calibrate the bath temperature with a small-range, semi-immersion thermometer or other temperature device; if the displayed temperature is within ±0.1 ℃ of the set temperature of the liquid bath temperature regulator, adjust the liquid bath temperature regulator according to the manufacturer's recommendations so that the set value and displayed temperature of the liquid bath temperature are consistent. Note: The thermometer should be calibrated with an ice-water mixture.
    • 10.1.4 Install according to the manufacturer's guidelines using the temperature controller calibration and test program.
    • 10.1.5 Set the cold bath temperature at −5 ℃ until calibration or the test program begins.
  • 10.2 Clean and prepare the test chamber, rotor hook connection, and stator.
    • 10.2.x Check that the rotor support stand and hook connection are vertical according to the manufacturer's guidelines.
    • 10.2.x Carefully connect the viscosity hook of the upper rotating thread to the viscosity rotating bracket connector, especially the viscosity rotating bracket connector; turn gently to the left to avoid wearing the jewel pivot inside the viscosity head.
    • 10.2.x When the viscosity head rotates at 12 r/min speed, check whether the hook of the viscosity head is vertical and whether it swings. If there is swinging, the viscosity head must be repaired or reinstalled.
  • 10.x Preheat the sample in the preheater to 90 ℃ ± 2 ℃.
  • 10.x Turn on the dry gas, and pass it through so that the flow rate to each test chamber is 10 mL/min～20 mL/min.
  • 10.x Install the test chamber and viscometer head, and use a Newtonian reference oil of known viscosity and suitable range as the standard sample for the test method.
  • 10.x According to the manufacturer's guidelines, select the dedicated calibration procedure shown in Table 1 on the program-controlled cold bath, but do not start the program.
  • 10.x Start the computer program and input the viscosity and temperature data of the calibration oil.
  • 10.x Control the valve in each test chamber so that dry gas flows over the surface of the specimen in the stator at a flow rate of approximately 10 mL/min.
  • 11.x Record data on the computer according to the cold bath manufacturer's guidelines.
  • 11.x Collect and analyze all recorded data according to the program developer's guidelines.
  • 11.x Correlation coefficient R ≥ 0.999, otherwise recalibrate to check the results; if there is still no improvement, contact the program developer or equipment manufacturer.
• 13 Test Procedure
  • 13.1 Computer Program
    • 13.1.1 Measure unknown specimens in the program-controlled liquid cold bath according to the cooling program and guidelines provided by the equipment manufacturer.
    • 13.1.2 Set the cold bath temperature and maintain it at −5 ℃ until the test begins.
  • 13.2 Input the specimen and test chamber code into the computer program according to the equipment manufacturer's guidelines.
  • 13.3 Correctly preheat the specimen according to Clause 12.2 to prepare for analysis. The preheating steps should be strictly followed as specified.
  • 13.4 Adjust the zero point of the viscometer head according to the equipment manufacturer's guidelines.
  • 13.5 Place the test chamber into the regulator according to 12.3.1 and the manufacturer's guidelines.
  • 13.6 After hooking the rotor shaft onto the viscometer drive shaft, firmly secure the test chamber and regulator to the viscometer head.
  • 13.7 Remove the specimen from the preheater and place the assembled test chamber and viscometer head into the program-controlled liquid cold bath within 20 min.
  • 13.8 Set the dry gas to flow into each test chamber at a flow rate of approximately 10 mL/min.
  • 13.9 Set the viscometer rotation speed to 12 r/min and maintain for 10 min to make the oil sample uniform, then set the rotor speed to 0.3 r/min. Note: The precision of the method is determined based on statistical tests. It can be observed that for some oil samples with high viscosity, when the rotation speed is 12 r/min and uniform, the rotor torque exceeds the maximum value; to prevent damage to the viscosity head, the rotor stops. Statistical analysis data show that this phenomenon has no test results in the statistical outline of the database. Therefore, it is concluded that because the torque value is too large, the homogenization step stops, and the test method is still invalid.
  • 13.10 Observe the viscometer torque or viscosity readout; when the viscometer reading stabilizes at −5 ℃ (about 15 min), start the computer program, and the test begins simultaneously.
    • 13.10.1 Start the cooling program of the cold bath.
    • 13.10.2 Record data on the computer according to the equipment manufacturer's guidelines.
    • 13.10.3 At the end of the test, the computer performs data analysis to obtain the critical pumping temperature, gel index, and gel index temperature of the specimen.
    • Note: Before using the computer program, the calibration of the viscometer and test chamber in Chapter 11 must be completed; otherwise, the program cannot receive the information generated during specimen analysis.

9. Qualitative and Quantitative and Calculation Formulas

• 3.6 Viscosity = shear stress / shear rate (Formula 1); viscosity unit mPa·s.
• 3.16 Gel index (GI) formula: GI = −[(log log η₁) − (log log η₂)]/(log T₁ − log T₂)……(2) Where: GI— gel index; η₁—dynamic viscosity at temperature T₁; η₂—dynamic viscosity at temperature T₂; T₁—Kelvin temperature at a certain point; T₂—Kelvin temperature of T₁−1. Note: Obtaining the gel index requires studying and applying the information obtained from the recorded chart, and then applying the empirical equation MacCoull-Walther-Wright equation. For further information, see viscosity-temperature relationship table GB/T 8023.
• 3.18 Gel index temperature: the Celsius temperature at which the gel index appears.
• 3.12 Critical pumping temperature: the temperature of the viscosity cell when the oil reaches the specified critical pumping viscosity (see 5.13, the original clause number is suspected to be 3.13, requires confirmation against the source standard (source-text extraction)).
• 3.13 Critical pumping viscosity: the apparent viscosity that causes engine pumping problems; the apparent viscosity is selected to test the critical pumping temperature of the base oil.
• 14.1 Report the temperature values related to the following viscosities: 5000 mPa·s, 15000 mPa·s, 25000 mPa·s, 40000 mPa·s, 60000 mPa·s.
• 14.2 If the user selects critical pumping viscosity as the indicator, report the associated critical pumping temperature.
• 14.3 Report the gel index and gel index temperature.

10. Precision

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

• 15.1 Critical temperature precision:
  • 15.1.1 Repeatability (r): The difference between two test results obtained by the same operator using the same equipment under the same operating conditions on the same specimen must not exceed 1.1 ℃.
  • 15.1.2 Reproducibility (R): The difference between two test results obtained by different operators in different laboratories on the same specimen must not exceed 1.4 ℃.
• 15.2 Gel index precision:
  • 15.2.1 Repeatability (r): must not exceed 11% of the mean.
  • 15.2.2 Reproducibility (R): must not exceed 27% of the mean.
• 15.3 Gel index temperature precision:
  • 15.3.1 Repeatability (r): must not exceed 0.7 ℃.
  • 15.3.2 Reproducibility (R): must not exceed 2.8 ℃.
• 15.4 Viscosity precision:
  • 15.4.1 Repeatability (r): must not exceed 8% of the mean.
  • 15.4.2 Repeatability (R): shall not exceed 14%.
• 15.5 The statistical test research report includes 6 laboratories and 7 oil samples; the viscosity range of the oil samples measured in the study is 4000 mPa·s～90000 mPa·s, the gel index range is 4.0～14.5, and the gel index temperature range is −5 ℃～−40 ℃.
  • Note: Equipment for establishing precision: (a) viscosity head—TAVII; (b) temperature-controlled cooling chamber—TANNAS company's 2 gallon, 4 gallon, 8 gallon programmable low-temperature cooling chamber; (c) matching stator and rotor TANNAS company part numbers: stator number #1055; rotor number #1030; (d) operating procedure—TANNAS company SBT application program.
• 15.5 (the second 15.5 in the original text, suspected to be 15.6, requires confirmation against the source standard (source-text extraction)) Bias: Because there is no acceptable reference material suitable for determining this test method, the bias cannot be determined.

11. Report

• 14.1 Report the temperature values related to the following viscosities: 5000 mPa·s, 15000 mPa·s, 25000 mPa·s, 40000 mPa·s, 60000 mPa·s.
• 14.2 If the user chooses the critical pumping viscosity as the indicator, report the critical pumping temperature associated with it.
• 14.3 Report the gel index and gel index temperature.
• Note: The gel index is a measure of the increase in the viscosity-temperature relationship of an oil. The value of the gel index is an important parameter for developing an oil without gel. For engine oils, this constant is less than 6 and any oil given can be repeated. To avoid some people thinking that any gel index implies gel, it is better to report that the gel index is less than 6 than to report a specific value. For other people, who believe that the gel index is a measurement method for testing the viscosity-temperature relationship of an oil, the gel index is important to them, no gel exists, and the actual gel index value is reported.
• Note: For samples without a gel index, the temperature of the gel index is meaningless, so the temperature of the gel index is not reported.
• Note: For oils with a viscosity index above 90, when the temperature drops to −15 ℃, there is no gel, and the average value of the gel index is above 6; the operator needs to verify the calibration and conditions of the instrument.

12. Normative References

• GB/T 4756 Petroleum liquids—Manual sampling (GB/T 4756—1998, eqv ISO 3170:1998)
• GB/T 8023 Viscosity-temperature charts for liquid petroleum products
• GB/T 9171 Standard test method for borderline pumping temperature of engine oils
• SH/T 0562 Standard test method for yield stress and apparent viscosity of engine oils at low temperature

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 Q&A Reference