SH/T 0750-2005 Determination of high-temperature oxidative deposits in engine oils (thermal oxidation simulation test method)

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Card type: Test method

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

• Method number: SH/T 0750—2005
• Chinese full name: Determination of high-temperature oxidative deposits in engine oils (thermal oxidation simulation test method)
• English name: Standard test method for determination of high temperature deposits by thermo-oxidation engine oil simulation test
• Replacement relationship: not provided in the available source (the foreword only states modified adoption of ASTM D6335-98, and does not mention replacing an old standard number)
• Adoption relationship: modified adoption of ASTM D6335-98 "Standard Test Method for Determination of High-Temperature Deposits by Thermal Oxidation Engine Oil Simulation Test"
• Editorial modifications: the chapter on keywords in ASTM D6335-98 is deleted; the precision statement is modified according to Chinese standard drafting practice; the statistical data content related to the precision of this standard in clause 17.1 and table 2 of ASTM D6335-98 is deleted
• Publication/implementation: published on 2005-04-11, implemented on 2005-09-01
• Proposing/administrative authority: proposed by China Petrochemical Corporation; administratively managed by the Research Institute of Petroleum Processing, Sinopec Corp.
• Drafting units: Lubricant Shanghai Branch of Sinopec Corp., Lubricant Research and Development Center of PetroChina Company Limited
• Main drafters: Lu Guofei, Liu Ying, Cai Zhuhua, Liu Jianxin
• Nature of appendices: Appendix A, Appendix B, and Appendix C are all normative appendices

2. Scope of application and non-applicability

• 1.1 This standard specifies a method for determining deposits produced by engine oils under high-temperature oxidation simulation test conditions (TEOST).
• 1.2 This method is applicable to detecting the tendency of engine oils to produce deposits under high-temperature oxidation conditions; interlaboratory studies show that this method can be used to determine samples with total deposits between 10mg and 65mg.
• Note: Operating experience with the test method indicates that this method is also applicable to samples with total deposits from 2mg to 180mg.
• 1.3 This standard involves certain hazardous materials, operations, and equipment, but it is not intended to address all safety issues associated with them; users should establish appropriate safety and protective measures before use and determine applicable management systems.
• 1.4 This standard uses [SI] International System of Units units.
• Non-applicability: no explicitly listed non-applicability clauses are provided in the available source.

3. Method principle

After an engine oil sample containing iron naphthenate is heated to 100℃ and contacted with nitrous oxide (NO) and wet air, it passes through a weighed deposition rod at a certain pump speed. The temperature of the deposition rod changes periodically between 200℃ and 480℃, and the entire test undergoes 12 cycles, with each cycle lasting 9min 30s. After the 12 cycles end, the deposition rod is cleaned and dried to obtain the mass of rod deposits. The sample released in the system flows through a weighed filter. The sum of the rod deposits and the filter deposits is the mass of total deposits.

4. Reagents and materials (purity / preparation)

• 6.1 Nitrous oxide (NO): compressed gas cylinder, medical grade.
• 6.2 Wet air: hydrocarbon-free air is pressurized to 103.4kPa before passing through the flowmeter, then passed through 30mL distilled water contained in a 50mL conical flask.
• 6.3 Iron naphthenate solution: solvent oil containing 6% iron.
• 6.4 n-Hexane: industrial grade.
• 6.5 Acetone: analytical reagent.
• 6.6 Low-deposit reference oil: CG-1 reference oil is a petroleum fraction that can produce total deposits in the range of 20mg to 30mg.
• 6.7 Medium-deposit reference oil: CF-1 reference oil can produce total deposits in the range of 50mg to 60mg.
• 6.8 Pump speed calibration oil: TPC calibration oil.
• Note: CG-1, CF-1 reference oil, and TPC calibration oil can be purchased from Tannas Company (the original text source-text extraction is "Taas", requires confirmation against the source standard (source-text extraction)).
• Sample preparation with iron added (10.1): add 193g iron naphthenate solution (see clause 6.3) to the 116mL sample; at this time, the iron content in the sample is approximately 100 mg/kg. (The original text "193g" is suspected to be "0.193g" or a similar order of magnitude, requires confirmation against the source standard (source-text extraction))

5. Apparatus and equipment

• 5.1 Engine oil thermal oxidation simulation test equipment (see Figure 1).
• 5.2 Balance: accuracy of 0.1mg.
• 5.3 Vacuum source.
• 5.4 Magnetic stirrer and stir bar.
• 5.5 Digital timer.
• 5.6 O type O-ring: oil-resistant and high-temperature resistant.
• 5.7 Ceramic insulation.
• 5.8 Polypropylene filter.
• 5.9 Plastic filter support.
• 5.10 Plastic hardening dish: used to receive the filtrate.
• 5.11 Filter flask: 1000mL.
• 5.12 Graduated filter funnel: 500mL.
• 5.13 Graduated cylinder: 10mL, 150mL.
• 5.14 Beaker: 25mL, 600mL.
• 5.15 Conical flask: 50mL.
• 5.16 Adjustable wrench.
• 5.17 Cleaning tube: 3mm × 304.8mm.
• 5.18 Steel wool: 4/0 (extra fine).
• 5.19 Copper brush: 0.22 diameter.
• 5.20 Glass syringe: 100μL.
• 5.21 Flowmeter: capable of measuring air flow from 0mL/min to 10mL/min.
• 5.22 Cartridge filter from Tannas Company (optional, see note).
• Note: If the cartridge filter from Tannas Company is used, clauses 5.8, 5.9, and 5.10 are not required.

6. Recommended operating conditions

• Reaction chamber set temperature: 100℃ (9.5); during the test, the sample should reach 100℃ within 15min (11.1); pour in the sample when the reaction chamber temperature reaches 100℃±5℃ (11.1).
• Deposition rod temperature program (Table 1 temperature input program):
  • Program mode setting 0: 200℃
  • Time 1: 1.25min; setting 1: 200℃
  • Time 2: 1.00min; setting 2: 480℃
  • Time 3: 2.00min; setting 3: 480℃
  • Time 4: 4.00min; setting 4: 200℃
  • Time 5: 1.25min; setting 5: 200℃
  • Time 6: 0min; cycles: 12 times
• Gas flow: both wet air and NO flow are 3.5mL/min (9.6).
• Liquid flow: 0.49mL/min (after calibration with TPC calibration oil, the pump flow rate is 0.40g/min) (11.7, A.1.1).
• Stirring speed dial: 50 (11.1).
• Pump dial flush setting: 999 (11.2, 11.7, 12.13); stop setting: 000 (11.2, 12.1, 12.13).
• Test time: 1h54min (12.1).
• Wet air pressurization: 103.4kPa (6.2).

7. Sampling and sample preparation

• 10.1 After thoroughly mixing the sample, use a 150mL graduated cylinder to measure 116mL sample, pour it into a 600mL beaker, and use a syringe to add 193g iron naphthenate solution (see clause 6.3) to the 116mL sample. At this time, the iron content in the sample is approximately 100 mg/kg. ("193g" requires confirmation against the source standard (source-text extraction))
• 10.2 Use a magnetic stirrer to thoroughly mix the iron naphthenate solution and sample for 5min.

8. Analytical procedure

• Calibration (Chapter 7):
  • 7.1 The thermal oxidation simulation test machine can be verified with medium- and low-deposit reference oils (perform according to Chapter 8 to Chapter 16). The calibration results should be within the repeatability range provided by the reference oil supplier.
  • 7.2 According to the instrument manufacturer's recommendations, perform verification at least once every three months.
  • 7.3 If the repeatability is not within the specified range, reinstall the instrument according to the procedure in Chapter 8, then retest with the reference oil.
• Instrument installation (Chapter 8):
  • 8.1 Pump speed calibration: complete according to the requirements of Appendix A; it is recommended to calibrate 1 times every three months.
  • 8.2 Thermocouple installation depth: complete according to the method in Appendix B; the installation depth should be checked every day; when installing a new thermocouple, the installation depth should be re-determined.
  • 8.3 Power adjustment: according to the method in Appendix C; it is recommended that this be performed by qualified instrument technicians.
  • 8.4 Correctly input the temperature program according to Table 1; after confirming it is correct, press the "RETURN" key to display the status.
• Equipment assembly (Chapter 9):
  • 9.1 Install the thermal oxidation simulation test system, place the reaction chamber on the test machine platform base, and note the positions of the air inlet tube and oil outlet.
  • 9.2 Connect the pump inlet tube so that it connects to the outlet of the reaction chamber, and tighten it by hand.
  • 9.3 Connect the pump outlet tube, and place a 10mL graduated cylinder at the opening of the pump outlet tube.
  • 9.4 There is a position on the cover above the reaction chamber where the thermocouple can be inserted; after confirming that the thermocouple contacts the bottom of the reaction chamber, cover it.
  • 9.5 Wrap the heating jacket around the outside of the reaction chamber, insert the heating jacket and thermocouple plugs into the marked instrument sockets; the reaction chamber set temperature is 100℃.
  • 9.6 Connect the gas conduit to the reaction chamber, set both the wet air and NO flow to 3.5mL/min; purge the line with this mixed gas before starting the test. Note: Ensure that the valve located on the reaction chamber is open and points upward so that gas can pass through the reaction chamber.
• Operating procedure (Chapter 11):
  • 11.1 When the reaction chamber temperature reaches 100℃±5℃, pour the sample into the reaction chamber, use the speed dial located on the right side of the instrument, set the stirring speed dial to 50, and the sample should reach 100℃ within 15min.
  • 11.2 Using the dial on the front panel of the instrument, set the pump dial to 999, and use a 10mL graduated cylinder to collect 10mL of sample at the pump outlet; after flushing is complete, set the pump dial to 000, and pour the outflowing 10mL of sample into the waste oil container.
  • 11.3 Rinse the new deposition rod with n-hexane; scrub the upper, middle, and lower parts of the deposition rod with steel wool in an up-and-down direction, 20 times for each part; use a cleaning tube dipped in acetone to clean the inner wall of the deposition rod, then rinse the deposition rod inside and out with acetone, and repeat this operation from the opposite direction; hold the deposition rod with the index finger and thumb, and dry it under a vacuum source; minimize finger contact, especially avoid contact with the middle part of the deposition rod; weigh accurately to 0.1mg, and record as the initial mass of the deposition rod.
  • 11.4 Assembly of the deposition rod assembly (see Figure 2): put a new O type O-ring onto one end of the weighed deposition rod, and insert it into the clean deposition rod outer sleeve, so that the distance the deposition rod protrudes from the deposition rod outer sleeve is essentially the same; point the thin end of the ceramic insulator toward the end of the deposition rod, and screw on the end cap nut, but do not tighten it too much; install the other end in the same way; adjust the position of the deposition rod in the deposition rod outer sleeve until the shoulder of the rod is visible from the inlet and outlet of the deposition rod outer sleeve; after assembly, tighten the side nut and end nut.
  • 11.5 Place the assembled deposition rod assembly vertically on the support arm of the instrument, ensuring that the larger connection port for connecting the drain oil pipe is at the top; insert the overheat protection thermocouple into the center hole at the lower end of the deposition rod, and do not let it bend during insertion (ensure that the deposition rod does not move in the middle of the sleeve); install the "hex socket screws" on the support arm, and the waxing part of the deposition rod should be higher than the upper support arm by 2m (requires confirmation against the source standard (source-text extraction), suspected to be 2mm), then tighten all 4 "hex socket screws". Note: do not overtighten.
  • 11.6 Connect the pump outlet pipe to the inlet of the deposition rod outer sleeve, connect the overflow pipe to the outlet of the deposition rod outer sleeve, tighten the nuts at both ends with fingers or a wrench, and the installation part is complete.
  • 11.7 Set the pump dial again to 999, and let the sample flow through the entire system; when the system is filled with sample and flows out of the overflow pipe back to the reaction chamber, set the pump dial reading to an appropriate value so that the liquid flow rate reaches 0.49mL/min (after calibration with TPC calibration oil, the pump flow rate is 0.40g/min).
  • 11.8 Insert the thermocouple into the center hole of the deposition rod; the thermocouple depth is determined by thermocouple depth verification, and a gauge can be used to determine the thermocouple depth; be careful to prevent the thermocouple from bending during insertion, as it will affect its depth in the rod.
  • 11.9 Turn on the main heating switch on the front panel of the instrument, start the test, and press the control key "START/STOP" key.
• End of test (Chapter 12):
  • 12.1 The instrument indicates the end of the test by the flashing of "MAN (manual)" on the control panel, and the test time is 1h54min; when the test ends, turn off the main heating switch and gas source, set the pump dial to 000, turn off the heating switch, and remove the heating jacket outside the reaction chamber. Warning: the reaction chamber and heater are at high temperature.
  • 12.2 Place a 25mL beaker at the connection between the inlet of the deposition rod outer sleeve and the outlet of the pump to collect the outflowing sample.
  • 12.3 Carefully remove the overflow pipe connected to the deposition rod outer sleeve, and rinse with n-hexane into the 600mL beaker.
  • 12.4 Loosen the "hex socket screws" on the support arm; one "hex socket screw" should be removed from the top of the support arm, and the others should be loosened; remove the deposition rod outer sleeve from the support arm.
  • 12.5 Place the deposition rod outer sleeve in a 600mL beaker, and rinse with n-hexane.
  • 12.6 Carefully remove the end nut, ceramic insulator, and O type O-ring from the deposition rod outer sleeve assembly, so as not to dislodge the deposit on the rod.
  • 12.7 Carefully pull the deposition rod vertically out of the deposition rod outer sleeve, and place the deposition rod outer sleeve back into the 600mL beaker.
  • 12.8 Hold one end of the rod with the thumb and index finger, and carefully rinse the inside and outside of the deposition rod with n-hexane, especially the deposition area; sample adhering in cracks in the deposit will cause an increase in mass.
  • 12.9 After rinsing, dry the interior of the deposition rod with vacuum or low-pressure air. Warning: do not dry the deposition rod with dry air.
  • 12.10 Place the deposition rod on the balance with the thumb and index finger, and weigh accurately to 0.1mg; do not put the deposition rod down before weighing, place the deposition rod on the balance for 1min, and ensure that all solvent has evaporated; a decrease in mass indicates that the solvent is not dry, and final constant weight is still required; after constant weight, record it and place the deposition rod in a plastic tube.
  • 12.11 Place a 600mL beaker at the overflow pipe of the reaction chamber, open the valve to drain the sample from the reaction chamber, rinse the outer sleeve of the deposition rod with n-hexane, and remove it from the beaker.
  • 12.12 Remove the pump inlet pipe together with the reaction chamber from the pump inlet; after the reaction chamber cools, rinse with n-hexane and drain into a beaker. Warning: when the reaction chamber temperature is high, do not rinse with n-hexane; n-hexane vapor is flammable.
  • 12.13 Set the pump speed to 999, and pump the sample in the pump outlet pipe into the 25mL beaker mentioned in clause 12.2; when the sample is completely drained, set the pump speed to 000; then, remove the pump inlet pipe from the reaction chamber, rinse with n-hexane, and pour into the 600mL beaker.
  • 12.14 Pour the sample in the 25mL beaker into the 600mL beaker, and rinse the 25mL beaker with n-hexane.
  • 12.15 Rinse the connection between the pump inlet pipe and the reaction chamber with n-hexane, and pour into the 600mL beaker.
• Sample filtration (Chapter 13):
  • 13.1 Assemble the filter system: place 5 polypropylene gaskets on the plastic filter receiver, and tighten the top and bottom screws. Note: if a cartridge filter from company Tannas is used, the steps in clause 13.2 may be carried out.
  • 13.2 Connect the filter funnel to the top of the filter, and connect the lower end to the filter flask; with the vacuum pump off, connect to the side tube of the filter flask (see Figure 3).
  • 13.3 Pour 5mL of n-hexane through this system 10 times (total 50mL) to remove soluble substances in the filter; then turn on the vacuum pump and let the filter dry for 15min.
  • 13.4 Weigh and dry the filter to constant weight, and record this mass as the initial mass of the filter.
  • 13.5 After obtaining the mass of the clean filter, connect the filter and the filtration system again; under vacuum, slowly filter the contents of the 600mL beaker; with the vacuum off, rinse around the funnel with n-hexane, in units of 10mL, add 100mL of n-hexane, let the n-hexane pass through the filter, and ensure thorough rinsing; turn on the vacuum pump again to allow the n-hexane to pass completely through the filter.
  • 13.6 When filtration is complete, turn on the vacuum pump and let the filter dry for 15min.
  • 13.7 Remove the filter from the filtration system and weigh it; then, place the filter in the system and dry for 5min, weigh again until constant weight; record as the final mass of the filter.
• Cleaning (Chapter 14):
  • 14.1 Before each thermal oxidation simulation test, the components must be rinsed with n-hexane to remove oil contamination; if the components are to be used immediately, air or a vacuum system may also be used to accelerate drying; the reaction chamber, pump, pump inlet and outlet pipes, deposition rod outer sleeve, and overflow pipe must be cleaned before use.
  • 14.2 In addition to rinsing with n-hexane, all deposits on the inner wall of the deposition chamber should be scraped off, and the brass brush mentioned in clause 5.19 should be used to brush off internal deposits, followed by rinsing with n-hexane. Note: because the bristles of the brass brush wear out, it should be replaced regularly.
  • 14.3 The pump inlet and outlet pipes have finger cots at the ends, and the fittings are sealed with O type O-rings; new sealing rings are required for each test to ensure sealing.

9. Qualitative and Quantitative and Calculation Formulas

• 15.1 Mass of rod deposit m₁, accurate to 0.1mg:
  • m₁ = A − B … (1)
  • Where: m₁—mass of rod deposit, mg; A— mass of deposition rod after test, mg; B— mass of deposition rod before test, mg.
• 15.2 Mass of deposit in filter m₂, accurate to 0.1mg:
  • m₂ = C − D … (2)
  • Where: m₂—mass of filter deposit, mg; C— mass of filter after filtration, mg; D— mass of filter before filtration, mg.
• 15.3 Total mass of deposit m, accurate to 0.1mg:
  • m = m₁ + m₂ … (3) (the original source-text extraction is "m= mi-m", suspected to be "m = m₁ + m₂", requires confirmation against the source standard (source-text extraction))
  • Where: m— total mass of deposit, mg; m₁—mass of rod deposit, mg; m₂—mass of filter deposit, mg.
• Appendix A Pump speed calibration calculation:
  • V = M / t
  • Where: V— pump flow rate, g/min; M—10 mass of TPC drops of calibration oil, g; t—10 time used for TPC drops of calibration oil, min.
  • Y = kX + b … (A.2)
  • Where: Y— pump speed set value; k— slope; X—0.40g/min; b— intercept.
  • The linear regression correlation coefficient should be greater than 0.999, and the intercept should be within 0±50, otherwise recalibrate (A.2.16).

10. Precision

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

• 17.1 Repeatability (r): For the same operator, using the same instrument, under the same operating conditions, testing the same sample, the difference between the two test results obtained shall not exceed the calculated value of formula (4).
  • r = 3.058 × X^0.33 … (4) (the original source-text extraction is "r= 3.058 X0.33", requires confirmation against the source standard (source-text extraction))
  • Where: X— arithmetic mean of the two results of repeated determinations, mg.
• 17.2 Reproducibility (R): when the same test sample is analyzed by different operators in different laboratories, the difference between the two test results obtained shall not exceed the value calculated by formula (5).
  • R = 4.774 × X^0.38 … (5) (the source text source-text extraction is “R= 4.774X0.38”, requires confirmation against the source standard (source-text extraction))
  • Where: X— the arithmetic mean of the two determination results obtained by different laboratories, mg.
• Note: the foreword states that the content of 17.1 clause and the statistical data related to the precision of this standard in Table 2 in ASTM D6335-98 has been deleted.

11. Report

• 16.1 Report the filter deposit mass, the rod deposit mass, and the total deposit mass, to the nearest 0.1mg.

12. Normative References

• ASTM D6335-98 “Standard Test Method for Determining High-Temperature Deposits Using a Thermal Oxidation Engine Oil Simulation Test” (modified adoption)
• No other list of normative references is 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