SH/T 0732-2004 Determination of the relationship between viscosity and temperature of lubricating oils at low temperature and low shear rate (temperature scanning method)

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Card type: Test method

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

• Standard number: SH/T 0732—2004
• Chinese full name: Determination of the relationship between viscosity and temperature of lubricating oils at low temperature and low shear rate (temperature scanning method)
• English name: Standard test method for low temperature, low shear rate, viscosity/temperature dependence of lubricating oils using a temperature-scanning technique
• Replacement relationship: not provided in the available source (the foreword does not mention replacement of any standard)
• Adoption relationship: modified adoption of ASTM D5133-99 (foreword)
• Publication/implementation: published on 2004-04-09, implemented on 2004-09-01 (cover)
• Proposed by/under the jurisdiction of/drafted by: proposed by China Petroleum & Chemical Corporation; under the jurisdiction of the Sinopec Research Institute of Petroleum Processing; drafted by the Lubricant Research and Development Center of PetroChina Company Limited; main drafter Wei Wenyu (foreword)

2. Scope of application and non-applicability

• 1.1 This standard specifies a method for determining the apparent viscosity of engine oils at low temperature.
• 1.2 When the shear stress is lower than 100Pa, a shear rate approximately 0.28 s⁻¹ is produced (the source text source-text extraction writes “0.28'”, requires confirmation against the source standard (source-text extraction)). Within the temperature range of -5~-40℃ or from -5℃ until the viscosity exceeds 40000mPa·s, the sample is cooled at a rate of 1℃/h while its apparent viscosity is continuously measured.
• 1.3 The results determined by this standard are viscosity, the maximum viscosity growth rate (gel index), and the gel index temperature.
• 1.4 The applicability of this standard to petroleum products other than engine oils has not been determined.
• 1.5 This standard does not address all safety issues associated with its use; users should establish appropriate safety and protection measures before use and formulate corresponding management systems.
• 1.6 This standard uses International System of Units [SI] units.

3. Method principle

• Chapter 4 Method summary: Add about 20mL of sample to a glass stator, preheat at 90℃ for 1.5h, mount the test chamber containing the sample onto a suitable viscometer drive module, then immerse it in a liquid cooling bath and cool at a rate of 1℃/h within the temperature range of -5~-40℃. Input the data obtained from the viscometer drive module into a computer data processing program to give the gel index, gel index temperature, and critical pumping temperature at a selected viscosity (for example, 30000mPa·s or 40000mPa·s).
• Chapter 5 Significance and use: The viscosity performance of engine oils at low temperature and low shear rate determines whether the oil can flow to the oil pickup, enter the oil pump, and reach the parts requiring lubrication in sufficient quantity during low-temperature startup. Two flow problems have been identified: flow limitation and air entrainment; the first is related to oil viscosity, and the second is related to gelation. This standard uses a temperature scanning technique to continuously provide information on the rheological conditions of the oil within the test temperature range, and a single test can simultaneously obtain viscosity and gel index.
• 5.3 Gel index and gel index temperature: the first parameter is the maximum value of the torque growth rate caused by rheological changes during slow cooling of the oil, and the second parameter is the temperature at which the gel index occurs.

4. Reagents and materials (purity / preparation)

• 7.1 Calibration oils: Newtonian calibration oils with defined dynamic viscosity and viscosity index within the temperature range of -5~-35℃.
• 7.2 Gel index reference oils: CIR series non-Newtonian reference oils with known gel index and associated gel index temperature.
• 7.3 Latex sleeve: when the stator containing the sample is preheated in the preheater, a latex sleeve is used to seal it to prevent water vapor from condensing inside the stator.
• Dry gas: used to provide a dry atmosphere on the sample surface (6.4, 11.4, 13.9), flow rate about 10mL/min; the specific gas type is not provided in the available source.
• Purity and specific preparation method: not provided in the available source.

5. Apparatus and equipment

• 6.1 Test chamber: composed of a matched stator and rotor meeting the dimensional requirements (Figure 1).
  • 6.1.1 Rotor dimensions: length 65.5mm±0.1mm, diameter 18.40mm±0.02mm.
  • 6.1.2 Stator dimensions: diameter 22.05mm±0.02mm; the length ensures that the sample liquid level is at least 15mm below the coolant liquid level throughout the entire temperature range.
• 6.2 Viscometer drive module: a rotational viscometer drive module capable of generating an analog signal for transmission to an analog-to-digital converter or other analog signal data processor (for example, a chart recorder); with rotors and stators meeting the specifications of 6.1.1 and 6.1.2, it can measure at least 45000mPa·s.
• 6.3 Test chamber alignment device: ensures the test chamber is axially vertical, the rotor is correctly fixed in the stator, and the analytical instrument installation gives reproducible torque readings for each test.
  • 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 on 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 set temperature range, and can run either the calibration program or the test program.
• 6.6 Temperature controller: according to the settings of the calibration program and test program, controls the temperature within 0.1 of the selected temperature.
• 6.7 Computer, analog-to-digital converter, and analysis program: receive data from the viscometer operating module and convert it into the required information.
• 6.8 Preheater: can accurately control the temperature at 90℃±2℃ and the heating time after reaching the preheat temperature according to the program.
• 3.19 Preheater: used to heat the sample at 90℃±2℃ for 1.5h before testing.
• 3.20 Program-controlled liquid cooling bath: a liquid cooling bath with a temperature control device that can run the calibration and analysis portions of this test method according to a program.
• 3.21 Temperature controller: a program device that, through correct program control, raises or lowers temperature at a selected rate or series of steps while controlling the temperature range.
• 3.25 Test chamber: a combination of stator and rotor; the main components are shown in Figure 1.
• 3.26 Rotor: a titanium metal rotor whose dimensions should ensure reasonable sensitivity and range for the viscosity and gel determined by this test method.
• 3.27 Stator: a borosilicate glass tube with a precise inner diameter, into which a specified amount of test oil is added, and a specially manufactured rotor rotates inside the stator.
• 3.28 Stator clamp: clamps the stator so that it is fixed on the vertical device of the test chamber.
• 3.29 Test chamber vertical device: a device used to support the viscometer drive module while keeping the stator, rotor, and viscometer rotating shaft axially vertical, and allowing dry air to enter the test chamber to prevent fogging and frosting.
• 3.31 Viscometer drive module: the rotor drive device and torque sensing element of a rotational viscometer.
• 3.32 Viscometer module support: the alignment device of the test chamber that supports the viscometer drive module.

6. Recommended operating conditions

• Preheating: 90℃±2℃, hold for 1.5h (9.1, 12.2).
• Initial cooling bath temperature: -5℃ (9.2, 10.3, 13.1.2).
• Cooling rate: 1℃/h (1.2, 4, 6.5, Table 2).
• Cooling range: -5~-40℃ or until the viscosity reaches 40000mPa·s (Table 2).
• Viscometer speed: 0.3 r/min (13.10, the source text source-text extraction writes “0.3:/min”, requires confirmation against the source standard (source-text extraction)).
• Dry gas flow rate: about 10mL/min (11.4, 13.9).
• Sample equilibration time in the cooling bath: 15~30min (13.8).
• Start the computer program within 30min after the first sample is immersed in the cooling bath (13.11).
• Calibration curve requirements: the optimal curve slope value should be greater than 450, and the correlation coefficient R≥0.999 (11.7).
• The liquid cooling bath calibration steps are shown in Table 1; the sample information steps are shown in Table 2.

7. Sampling and sample preparation

• Chapter 8 Sampling: this test requires approximately 20mL of sample.
• 12.1 Pour the sample 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.
• 12.1.1 Input the sample and test chamber code into the computer program as required by the program.
• 12.1.2 Place the sample in the preheater.
• 12.2 Within the time determined in clause 9.1, bring the sample to 90℃±2℃ and hold at that temperature for 1.5h. After preheating, carefully remove the sample and holder from the preheater, remove the latex sleeve, and immediately carry out the steps of clause 13.4 when the glass stator has cooled enough to touch.
• Note: Heating the rotor with the stator and sample will greatly prolong the cooling time and is not permitted in this test.

8. Analysis procedure

• Chapter 9 Instrument preparation
  • 9.1 Preheat the sample with the preheater: select a program-controlled preheater so that the preheated sample temperature is constant at 90℃±2℃ and held for 1.5h.
  • 9.2 Liquid cooling bath preparation: check the liquid level of the program-controlled liquid cooling bath, and according to the manufacturer's instructions fill the cooling bath to the correct depth at -5℃. Install or check the cooling program of the program-controlled cooling bath; the operating steps are shown in Table 1 and Table 2.
  • 9.3 Check whether the threaded upper hook is tightly connected to the rotating shaft of the viscometer drive module; during tightening, be gentle and slightly lift the rotating shaft.
• Chapter 10 Test chamber calibration preparation
  • 10.1 At room temperature, pour the calibration oil into the stator up to the mark in Figure 1, and place it on a suitable rack to prepare for calibration. Note: Since the calibration oil is a Newtonian fluid within the low-temperature test range, it does not produce gel and does not require preheating.
  • 10.2 Computer data acquisition and analysis: refer to the user manual to establish the computer automatic analysis program.
  • 10.3 Turn on the program-controlled liquid cooling bath so that the temperature is controlled at -5℃.
• Chapter 11 Computer method calibration of the test chamber
  • 11.1 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.
  • 11.2 According to the manufacturer's guidelines, select the dedicated calibration step shown in Table 1 on the program-controlled cooling bath, but do not start the program.
  • 11.3 Start the computer program and input the viscosity and temperature data of the calibration oil.
  • 11.4 Open the main control valve in each test chamber to make dry gas flow over the surface of the specimen in the stator at a flow rate of approximately 10mL/min.
  • 11.5 Start the cooling step of the cold bath while recording data on the computer according to the cold bath manufacturer's guidelines.
  • 11.6 Collect and analyze all recorded data according to the program developer's guidelines.
  • 11.7 The optimal curve slope value obtained by taking the percentage of the collected viscosity/torque maximum should be greater than 450, and the correlation coefficient R≥0.999. Otherwise, recalibrate to check the results; if there is still no improvement, contact the program developer or equipment manufacturer to resolve.
• Chapter 12 Preparation for Specimen Analysis (see Section 7)
• Chapter 13 Test Procedure
  • 13.1 Program settings for the cold bath
    • 13.1.1 According to the equipment manufacturer's guidelines, prepare to measure unknown specimens in a program-controlled liquid cold bath using the dedicated cooling program shown in Table 2.
    • 13.1.2 Set the cold bath temperature and maintain it at -5℃ until the test begins.
  • 13.2 Enter the specimen and test chamber codes into the computer program according to the equipment manufacturer's guidelines. Note: Testing a gel index reference oil with known gel index and gel index temperature values helps verify the operator's technique, the cold bath, and the function of other equipment.
  • 13.3 Correctly preheat the specimen according to Chapter 12 and prepare for analysis. Note: The preheating step should be carried out strictly as specified.
  • 13.4 Adjust the zero point of the viscosity head according to the equipment manufacturer's guidelines.
  • 13.5 Insert the matching rotor at room temperature into the stator, prepare to connect it to the regulator/viscometer head support, and then immediately carry out the following preparation work and cold bath immersion step.
  • 13.6 Place the test chamber into the regulator according to the manufacturer's guidelines; when the test chamber and regulator are fixed to the viscometer head, be careful that no air bubbles adhere to the bottom of the rotor. If bubbles are found, tilt the assembly to one side until the bubbles slide out from the bottom of the rotor, then keep it upright again so the bubbles rise to the surface.
  • 13.7 After hooking the rotor shaft onto the viscometer drive shaft, firmly secure the test chamber and regulator to the viscometer head.
  • 13.8 Place the assembled test chamber and viscometer head into the program-controlled liquid cold bath; the specimen equilibrates in the cold bath for 15~30min.
  • 13.9 Dry gas flows to each test chamber at a flow rate of approximately 10mL/min.
  • 13.10 Set the viscometer speed to 0.3 r/min.
  • 13.11 Start the computer program within 30min after the first specimen is immersed in the cold bath, start the cooling step of the cold bath, and record data with the computer at the same time.
  • 13.12 At the end of the test, the computer performs data analysis to obtain the specimen's critical pumping temperature, gel index, and gel index temperature. Note: Before using the computer program, the viscometer and test chamber calibration in Chapter 11 must be completed; otherwise, the program cannot receive the information generated during specimen analysis.
• Table 1 Steps for obtaining calibration information with the liquid cold bath: cool to -5℃ and hold; set up data acquisition and start the program; collect data at -5℃; cool to -10℃ and hold; cool to -15℃ and hold; cool to -20℃ and hold; cool to -25℃ and hold; cool to -30℃ and hold; cool to -33℃ and hold; cool to -35℃ and hold; return to -5℃ and hold. (Time: partly uncertain, non-strict times, partly 30min, source-text extraction table misalignment, requires confirmation against the source standard (source-text extraction))
• Table 2 Steps for obtaining specimen information with the liquid cold bath: cool to -5℃ and hold; stabilize the cold bath at -5℃; set up data acquisition and start the program; cool to -40℃ or until the viscosity reaches 40000mPa·s; return to -5℃ and hold. (Time: partly uncertain, non-strict times, the cooling step is 1℃/h, requires confirmation against the source standard (source-text extraction))

9. Qualitative and Quantitative and Calculation Formulas

• 3.6 Definition of viscosity: Viscosity is the ratio of the applied shear stress to the shear rate.
  • Formula (1): η = τ / γ (the source source-text extraction writes "7=T/C", requires confirmation against the source standard (source-text extraction))
  • Where: η— viscosity, mPa·s; τ— shear stress, Pa; γ— shear rate, s⁻¹.
• 3.16 Gel index Gelation Index (GI): within the scanning temperature range, the maximum value of the increase in ratio during the process of continuously decreasing temperature by 1K.
  • Formula (2): GI = -1[(lglgη₁)-(lglgη₂)/(lgT₁-lgT₂)] (the source source-text extraction writes "CI= - 1[(lglg7:)-(lglg7)/(1gZ"-1gT2)]", requires confirmation against the source standard (source-text extraction))
  • Where: η₁—dynamic viscosity at temperature T₁, mPa·s; η₂—dynamic viscosity at temperature T₂, mPa·s; T₁—Kelvin temperature at a certain point, K; T₂—T₁-1, K.
  • Note: The technique for obtaining the gel index first requires studying and applying the information obtained from the recorded chart, and then applying the empirical equation MacCoull-Walther-Wright equation to calculate the gel index. For further information, see Appendix A.
• Appendix A Determination of Gel Index and Gel Index Temperature
  • A.1 Graphical analysis study: The graph recording viscosity-temperature data is shown in Figure A1. Use computer chart simulation for the automated method, develop a computer program to receive the data output by the viscometer module and convert it into the required values and plotting data.
  • A.2 Automatic gel index determination program: Using acceptable analog-to-digital conversion and related computer programs to simulate the curve graph, all required data for each test oil is automatically input, processed, and reported.
  • A.3 Steps for determining the gel index from the chart: Obtain the viscosity and temperature data for the test oil at each 1℃ interval from the graph.
  • A.3.1 Apply the MacCoull-Walther-Wright viscosity-temperature relationship (see GB/T 8023) to calculate the low-temperature dynamic viscosity:
    • Formula (A1): lg(lgη) = m·lgK + b (the source source-text extraction writes "lg(lgn) = m•lgK+b-", requires confirmation against the source standard (source-text extraction))
    • Where: η— viscosity, mPa·s; K— temperature, K; m— correlation coefficient; b— constant.
  • A.3.2 If the computer program analysis of viscosity-temperature data of this standard method is not used, tabular data analysis may be used; the table for gel oil products is shown in Table A.1. Note: Table A.1 shows that the Y/X value (H column) ends when the viscosity (E column) exceeds the torque range of the viscometer module (usually between 41000mPa·s and 55000mPa·s); in this example it ends at -16℃.
  • A.3.3 Report the highest value in the H column as the gel index (see note, example 1).
  • A.3.4 Report the Celsius temperature corresponding to it as the gel index temperature (see note, example 2).
  • Note: Table A.1 illustrates the application results of the collected data: Example 1, the highest value at -Y/X in Table A.1 is 31.1, which is the gel index of the specimen; Example 2, since the gel index 31.1 is at -12℃, this temperature is the gel index temperature of the specimen.
  • Table A.1 Tabular analysis of graphical data for gel specimens (including columns for temperature values and calculations, viscosity values and calculations; for specific values see Table A.1 in the source).

10. Precision

• Chapter 15 Precision and Bias (judge the reliability of test results according to the following provisions, 95% confidence level)
• 15.1 Precision
  • 15.1.1 The precision of the critical pumping temperature obtained from statistical tests is as follows:
    • 15.1.1.1 Repeatability (r): The difference between two test results obtained by the same operator using the same instrument under the same operating conditions on the same specimen shall not exceed 0.5℃.
    • 15.1.1.2 Reproducibility (R): The difference between two test results obtained by different operators in different laboratories on the same specimen shall not exceed 1.4℃.
  • 15.1.2 The precision of the gel index obtained from statistical tests is as follows:
    • 15.1.2.1 Repeatability (r): The difference between two test results obtained by the same operator using the same instrument under the same operating conditions on the same specimen shall not exceed 16% of the mean.
    • 15.1.2.2 Reproducibility (R): The difference between two test results obtained by different operators in different laboratories on the same specimen shall not exceed 29% of the mean.
  • 15.1.3 The precision of the gel index temperature obtained from statistical tests is as follows:
    • 15.1.3.1 Repeatability (r): The difference between two test results obtained by the same operator using the same instrument under the same operating conditions on the same specimen shall not exceed 1.5℃.
    • 15.1.3.2 Reproducibility (R): The difference between two test results obtained by different operators in different laboratories on the same specimen shall not exceed 1.7℃.
  • 15.1.4 Statistical test research report ASTM RRD02-1448 includes eight oil samples from 19 laboratories; in the study, the measured specimen viscosity range was 5000mPa·s–40000mPa·s, the gel index range was 4.5–38.2, and the gel index temperature range was -18.0~-31.0℃.
• 15.2 Bias: Since there is no acceptable reference material suitable for determining the bias of this test method, no bias is specified.

11. Report

• 14.1 Report the temperature values at the following viscosities: 5000mPa·s, 10000mPa·s, 20000mPa·s, 30000mPa·s, 40000mPa·s, accurate to 0.1℃.
• 14.2 If the user of this test method chooses critical pumping viscosity as the indicator, report the critical pumping temperature, to the nearest 0.1℃. Note: Practice has shown that 30000mPa·s or 40000mPa·s reflects the pumping requirements of the engine.
• 14.3 If the gel index is greater than or equal to 6.0, report the gel index to the nearest 0.1, and the gel index temperature to the nearest 0.1℃. If the gel index is less than 6.0, report the gel index as less than 6.0, and do not report the gel index temperature. Note: This test method gives gel index values less than 6.0, which is useful for evaluating the consistency of the instrument and operation, and can also provide other information.

12. Referenced Documents

• GB/T 8023 Viscosity-temperature calculation chart for liquid petroleum products
• GB/T 9171 Determination of borderline pumping temperature of engine oils (the original source-text extraction is written as "CB/T 9171", requires confirmation against the source standard (source-text extraction))
• SH/T 0562 Determination of yield stress and apparent viscosity of engine oils at low temperature
• ASTM D5133-99 (modified adoption, see foreword)
• ASTM RRD02-1448 (statistical test research report, see 15.1.4)

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