SH/T 0805-2008 Determination of filterability of lubricating oils

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Card type: Test method

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

• Standard number: SH/T 0805—2008
• Chinese title: Determination of filterability of lubricating oils
• English title: Determination of the filterability of lubricating oils
• Adoption relationship: Modified adoption of ISO 13357-2:2005 "Petroleum products—Determination of filterability of lubricating oils—Part 2: Procedure for dry oils" and ISO 13357-1:2002 "Petroleum products—Determination of filterability of lubricating oils—Part 1: Procedure for oils in the presence of water", MOD
• Replacement relationship: not provided in the available source (the foreword does not mention replacement of any standard)
• Method division: Method one (dry method, corresponding to ISO 13357-2:2005); Method two (wet method, corresponding to ISO 13357-1:2002)
• Publication/implementation: published by 2008-04-23, implemented by 2008-10-01
• Issuing body: National Development and Reform Commission of the People's Republic of China

2. Scope of application and non-applicability

• 1.1 is applicable to the determination of the filterability of lubricating oils based on mineral oils, especially the filterability of hydraulic oils in hydraulic systems.
• 1.1 is applicable to oils with a viscosity grade not exceeding 100 as specified in the viscosity classification of GB/T 3141.
• 1.1 is not applicable to liquids based on other materials, such as fire-resistant fluids (which may have compatibility problems with the filter membrane used).
• 1.1 is not applicable to some hydraulic oils with special properties (containing insoluble or partially soluble additives or special macromolecular substances).
• 1.2 Method one: dry method, applicable to evaluating the filterability of lubricating oils under dry conditions.
• 1.3 Method two: wet method, applicable to evaluating the filterability of lubricating oils in the presence of water.
• Supplementary introduction: This test method can evaluate mineral oils with a viscosity grade of ISO not higher than 100, and is not applicable to oils of higher viscosity grades; the scope of application may be extended to fluids other than mineral oils, but some fluids (such as fire-resistant hydraulic fluids) are incompatible with the specified filter membrane, in which case the data can only be used for comparison purposes.

3. Method principle

• 4.1 (Method one, dry method) method summary: Under specified conditions, the sample passes through a filter membrane with an average pore size of 0.8 μm, and the time taken to filter a specified volume of sample is recorded. The filterability is calculated from the ratio of the initial filtration rate to the filtration rate of the last 100 mL, and the test result is the average of three determinations. Note: Ideally the filtration rate is constant.
• 5.1 (Method two, wet method) method summary: After the sample is treated with added water at high temperature, under specified conditions it passes through a filter membrane with an average pore size of 0.8 μm, and the time taken to filter a specified volume of sample is recorded. The filterability is calculated from the ratio of the initial filtration rate to the filtration rate of the last 100 mL, and the test result is the average of three test results. Note: Ideally the filtration rate is constant.
• Introduction: Stage I evaluates filterability using the ratio of the average flow rate of the fluid through the filter membrane to its initial flow rate; Stage II evaluates filterability using the ratio of the initial flow rate to the final flow rate of the fluid through the filter membrane. The test conditions of Stage II are more severe and are more sensitive to gels and fine residues.

4. Reagents and materials (purity / preparation)

• 4.2.1 Water: meets the grade three water requirements specified in GB/T 6682.
• 4.2.2 Propylene glycol (isopropyl alcohol): filtered through a compatible 0.45 μm filter membrane; the apparatus listed in Figure 1 may be used to filter the solvent. Note: Figure 1 is a solvent receiver with a filter membrane pore size of 0.45 μm, used for filtering propylene glycol and cleaning solvent.
• 4.2.3 Cleaning solvent: light alkanes, 2,2,4- trimethylpentane, filtered through a compatible 0.45 μm filter membrane.
• 4.2.4 Compressed gas: pressure adjustable, range 50 kPa～200 kPa; the gas should be dried and filtered.
• 5.2 (Method two): see 4.2.1～4.2.4.
• 5.6.4 Water: use a pipette to measure 0.66 mL ± 0.02 mL water into the bottle (used for adding water to the wet method sample).

5. Apparatus and equipment

• 4.3.1 Filter: as shown in Figure 2, stainless steel construction, consisting of a covered filter container with a volume of at least 350 mL and a filter membrane holder; the filter membrane can be fixed on the filter with good sealing performance; the device should be grounded; the effective filtration area is 1130 mm² ± 60 mm².
• 4.3.2 Filter membrane: ester fiber, diameter 47 mm, average pore size 0.8 μm. Note: Membranes with specifications equivalent to the WPO47TF type filter membrane of Millipore company can meet the requirements of this standard.
• 4.3.3 Graduated cylinder: made of hard glass. The first graduated cylinder has a capacity of 250 mL, used for measuring the sample volume in the test, with graduations at 10 mL and 300 mL (see Appendix A for the method of adding graduations). The second graduated cylinder can measure 320 mL ± 5 mL of sample, used for weighing the sample.
• 4.3.4 Pressure gauge: scale type or digital type, with readable graduations of 5 kPa (see 4.6.4).
• 4.3.5 Flat-tipped tweezers.
• 4.3.6 Timing device: stopwatch or other timer, electronic or mechanical, with a minimum scale of 0.2 s, having a double-stop function.
• 4.3.7 Oven: controllable temperature 70 ℃ ± 2 ℃.
• 4.3.8 Petri dish: with lid.
• 5.3 (Method two): see the test apparatus specified in 4.3.1, 4.3.2, 4.3.8.
• 5.3.1 Graduated cylinder: except that the second graduated cylinder can measure 330 mL ± 5 mL of sample, the rest is as required in 4.3.3.
• 5.3.2 Wide-mouth bottle: 500 mL, so that the stirrer can stir freely.
• 5.3.3 Stirrer and motor: rotational speed meets the requirements of the method in GB/T 7305.
• 5.3.4 Pipette or syringe: capacity 1 mL, minimum scale 0.01 mL.
• Appendix A.1 Apparatus (for adding graduations to graduated cylinders): A.1.1 graduated cylinder 250 mL; A.1.2 pipette (long enough to reach the bottom of the graduated cylinder, capacity about 20 mL); A.1.3 oven (temperature controllable at 500 ℃, or reaching a temperature usable for the decal process); A.1.4 balance (maximum range 500 g, sensitivity 0.1 g); A.1.5 decal paper (used for firing graduation lines on glassware).

6. Recommended operating conditions

• 4.6.4 The test pressure is determined by the viscosity grade of the sample, and the pressure control accuracy requirement is 5 kPa:
  • GB/T 3141 viscosity grade less than 32: 50 kPa
  • GB/T 3141 viscosity grade is 32 and 46: 100 kPa
  • GB/T 3141 viscosity grade is 68 and 100: 200 kPa
• 4.3.7 Oven temperature: 70 ℃ ± 2 ℃.
• 4.4.2 Sample storage: store at 15 ℃～25 ℃ for 24 h; the laboratory temperature change throughout the test shall not exceed ±2 ℃; Note: The most suitable laboratory temperature for precision determination is 22 ℃.
• 4.6.2 Filter membrane drying: place in the oven for 10 min, oven temperature 70 ℃ ± 2 ℃.
• 4.6.5 Mixing: within 60 s ± 10 s, invert and shake the sample container 30 times, with an interval between each inversion and shaking.
• 4.6.7 After removing the rubber stopper, open the control valve and adjust to the correct pressure; start timing when the sample drips into the graduated cylinder.
• 4.6.12 If the final time (Tf or T300) exceeds 7200 s (2 h), the test ends.
• 5.6.5 Oven placement after adding water in the wet method: 120 min ± 5 min, oven temperature 70 ℃ ± 2 ℃.
• 5.6.6 Stirring: 5 min ± 2 s, rotational speed 1500 r/min ± 50 r/min; the stirrer should be 5 mm from the bottom of the bottle.
• 5.6.7 Further placement: place in the oven again for 70 h ± 1 h; after about 30 min, tightly close the bottle cap to prevent moisture loss.
• 5.6.8 Store again at room temperature protected from light for 24 h ± 2 h; ideally the three water-treated samples should be prepared on the same day, and the sample filterability test can be carried out after four days.

7. Sampling and sample preparation

• 4.4.1 Unless otherwise specified, samples should be taken in accordance with GB/T 4756.
• 4.4.2 Shake the sample uniformly, store at 15 ℃～25 ℃ for 24 h; the laboratory temperature change throughout the test shall not exceed ±2 ℃.
• 5.4 (Method two) Sampling and sample preparation: see the provisions of 4.4.1 and 4.4.2.
• 5.6.3 Measure 330 mL ± 5 mL of sample separately with a graduated cylinder and pour into three wide-mouth bottles.
• 5.6.4 Use a pipette to measure 0.66 mL ± 0.02 mL of water and inject into the bottles. Note: Using a suitable syringe or pipette to transfer water can ensure sufficient precision.
• 5.6.8 Remove the sample and store it again at room temperature away from light for 24 h ± 2 h.

8. Analysis Procedure

Method One (Dry Method)

• 4.5 Instrument preparation:
  • 4.5.1 Rinse the instrument with cleaning solvent to wash away residual oil contamination from the previous test.
  • 4.5.2 Soak in detergent for 12 h or more, or thoroughly scrub with hot detergent.
  • 4.5.3 First rinse with hot tap water, then rinse with cold tap water.
  • 4.5.4 Rinse with water as specified in 4.2.1.
  • 4.5.5 Rinse with propylene glycol.
  • 4.5.6 First rinse with cleaning solvent, then air dry.
• 4.6 Test procedure (Figure 3 is a typical test result):
  • 4.6.1 The test is repeated three times.
  • 4.6.2 Use tweezers to hold the edge of the filter membrane and place it in a petri dish, cover loosely with the lid, and place in an oven at 10 min, oven temperature 70 ℃ ± 2 ℃.
  • 4.6.3 Install the filtration apparatus, place the filter membrane in the correct orientation, ensure the system is leak-free, and place the graduated cylinder shown in 4.3.3 in an appropriate position below the filter. Note: The correct orientation of the filter membrane is the face shown at the normal opening end of the packaging box.
  • 4.6.4 Close the control valve, adjust the gas pressure to the specified pressure according to the sample viscosity grade (see Section 6), pressure control accuracy requirement 5 kPa.
  • 4.6.5 Within 60 s ± 10 s, invert and shake the sample container 30 times to mix the sample uniformly, with an interval between each inversion and shake.
  • 4.6.6 Measure 320 mL ± 10 mL of sample and immediately pour into the filtration container, plug the filter outlet with a rubber stopper to prevent oil from flowing out.
  • 4.6.7 After 60 s ± 10 s, remove the rubber stopper, open the control valve, adjust to the correct pressure; start timing when the sample drips into the graduated cylinder.
  • 4.6.8 Use the dual-stop function of the timer to record the time required to filter to 10 mL, 50 mL, 200 mL, 300 mL of sample T10, T50, T200, T300.
  • 4.6.9 When filtered to 50 mL of sample, calculate Tf, Tf = 6 × (T300 − T10) + T10.
  • 4.6.10 Record the volume of sample filtered within the time in Tf.
  • 4.6.11 If only the stage I filterability is determined, the test ends after recording the volume required by 4.6.10.
  • 4.6.12 If the final time determined (Tf or T300) exceeds 7200 s (2 h), the test ends.
  • 4.6.13 After the test ends, close the control valve and pressure regulating valve, depressurize the apparatus, and disassemble the filter.
  • 4.6.14 Check the uniformity of the color of the filter membrane; if the color of the filter membrane is obviously non-uniform, the test must be repeated. Note: Non-uniform color of the filter membrane indicates that not all parts of the filter membrane were used during filtration of the oil, and the test results cannot be reproduced.

Method Two (Wet Method)

• 5.5 Instrument preparation: see provisions in 4.5.1～4.5.6.
• 5.6 Test procedure:
  • 5.6.1 The test is repeated three times.
  • 5.6.2 Within 60 s ± 10 s, invert and shake the sample container 30 times to mix the sample uniformly, with an interval between each inversion and shake.
  • 5.6.3 Measure 330 mL ± 5 mL of sample separately with a graduated cylinder and pour into three wide-mouth bottles.
  • 5.6.4 Use a pipette to measure 0.66 mL ± 0.02 mL of water and inject into the bottles.
  • 5.6.5 Loosen the bottle cap gently to avoid pressure rise, place in the oven, leave for 120 min ± 5 min, oven temperature 70 ℃ ± 2 ℃.
  • 5.6.6 Remove the sample, stir with a stirrer for 5 min ± 2 s, rotation speed 1500 r/min ± 50 r/min; during stirring, the stirrer should be 5 mm from the bottom of the bottle.
  • 5.6.7 After stirring the sample, loosen the bottle cap gently, place the bottle in the oven and leave for 70 h ± 1 h; after about 30 min, tighten the bottle cap to prevent moisture loss.
  • 5.6.8 Remove the sample and store it again at room temperature away from light for 24 h ± 2 h.
  • 5.6.9 Proceed according to 4.6.2～4.6.14, replacing the sample with the sample prepared in 5.6.8.

Appendix A Method for Adding Extra Graduations to a Graduated Cylinder

• A.2.1 Ensure the graduated cylinder is clean and dry.
• A.2.2 Accurately pour 50 mL of water into the graduated cylinder, ensuring the bottom of the water meniscus is exactly level with the middle of the 50 mL graduation line.
• A.2.3 Accurately weigh the graduated cylinder to the nearest 0.1 g, then use a syringe to withdraw water from the graduated cylinder until exactly 40 g ± 0.1 g of water is removed, so that the water level falls completely.
• A.2.4 Use the decal method to align the middle of the marked line with the bottom of the water meniscus, and keep the marked line horizontal.
• A.2.5 Pour water into the graduated cylinder up to the 250 mL graduation; for specific operational requirements see A.2.2.
• A.2.6 Accurately weigh the graduated cylinder to the nearest 0.1 g, then add 50 g ± 0.1 g of water; for specific operational requirements see A.2.2.
• A.2.7 Repeat step A.2.4.
• A.2.8 Empty the graduated cylinder and heat in an oven to make the markings clearer and more durable.

9. Qualitative and Quantitative Determination and Calculation Formulas

• 4.7.1 Stage I filterability F1 is calculated according to formula (1):
  • F1 = (V / 240) × 100 (original formula (1) source-text extraction displayed as F,=5=10×100., requires confirmation against the source standard (source-text extraction))
  • Where: V —— the volume of sample filtered within the time recorded in Tf as recorded in 4.6.10, mL; Tf —— the time shown in 4.6.9 Tf = 6 × (T300 − T10) + T10, s.
• 4.7.2 Stage II filterability F2 is calculated according to formula (2):
  • F2 = [2.5 (T300 − T10) / (T300 − T200)] × 100 (original formula (2) source-text extraction displayed as 2.5（Ts - Tio） / Ts -T20 × 100, requires confirmation against the source standard (source-text extraction))
• 5.7 (Method Two) calculation: proceed according to 4.7.1 and 4.7.2.
• 3.1 Definition of filterability: expressed as a percentage, the ratio of the specific volume of sample filtered (stage I) or the ratio of the filtration rate of the sample (stage II).
• 3.2 Stage I filterability: the ratio of the volume of sample filtered under ideal conditions without membrane filtration blockage to 240 mL, expressed as a percentage.
• 3.3 Stage II filterability: the ratio of the flow rate of the sample near the beginning to the flow rate when filtering 200 mL～300 mL, expressed as a percentage.

10. Precision

• 4.9 Precision (95% confidence level):
  • 4.9.1 Determination tolerance d: the difference between several determination values obtained by the same operator, using the same instrument, correctly operating according to the same method, on the same sample, shall not exceed the values of formula (3) and formula (4):
    • d (Stage I filterability) = 0.277 × X (100 − X) (original formula (3) source-text extraction displayed as 0.277 T（H00-X）, requires confirmation against the source standard (source-text extraction))
    • d (Stage II filterability) = 0.145 × X (100 − X) (original formula (4) source-text extraction displayed as 0.145 X（100-, requires confirmation against the source standard (source-text extraction))
    • Where: X —— the average value of the determination values being compared.
  • 4.9.2 Repeatability r: the difference between results obtained by the same operator, in the same laboratory, using the same instrument, correctly operating according to the same method, on the same sample, shall not exceed the values of formula (5) and formula (6):
    • r (stage I filterability) = 0.160 × X (100 − X) (original formula (5) source-text extraction shown as 0.160yX (100-X), requires confirmation against the source standard (source-text extraction))
    • r (stage II filterability) = 0.084 × X (100 − X) (original formula (6) source-text extraction shown as 0.084 X (100-X), requires confirmation against the source standard (source-text extraction))
    • Where: X — the average of the compared measured values.
  • 4.9.3 reproducibility R: different operators, in different laboratories, using different instruments, correctly operating according to the same method, the difference between two results obtained from measuring the same sample shall not exceed the values of formula (7) and formula (8):
    • R (stage I filterability) = 0.396 × X (100 − X) (original formula (7) source-text extraction shown as 0.396 K (100-X), requires confirmation against the source standard (source-text extraction))
    • R (stage II filterability) = 0.831 × X (100 − X) (original formula (8) source-text extraction shown as 0.831 X (100-X), requires confirmation against the source standard (source-text extraction))
    • Where: X — the average of the compared measured values.
• Table 1 Precision estimates (measured values or test results %: 0 / 30 / 50 / 70 / 90):
  • Stage I filterability: d = 8.3 / 12.7 / 13.8 / 12.7 / 8.3; r = 4.8 / 7.3 / 8.0 / 7.3 / 4.8; R = 11.8 / 18.1 / 19.8 / 18.1 / 11.8
  • Stage II filterability: d = 4.3 / 6.6 / 7.2 / 6.6 / 4.3; r = 2.5 / 3.8 / 4.2 / 3.8 / 2.5; R = 24.9 / 38.0 / 43.5 / 38.0 / 24.9
  • Note: In Table 1, the 50% column source-text extraction is shown as "220", requires confirmation against the source standard (source-text extraction).
• 5.10 (Method Two) precision: For test methods with results of "pass" or "fail", precision cannot be obtained. A test result less than 50 only indicates that this test "fails". Results from different laboratories show that when the test result is less than 50, the dispersion is poor, and when the test result is higher, the dispersion improves accordingly. The precision of the dry method determination in clause 4.9 may be used as a guide.

11. Report

• 4.8 Expression of results (Method One):
  • 4.8.1 If the three measured values meet the requirements specified in 4.9.1, report the average of the three measured values, accurate to 0.1. Filterability is reported in this form: "Stage X filterability AB.C". Note: Where "A", "B", "C" represent numbers, a typical test result is "76.2".
  • 4.8.2 If one of the three measured values does not meet the requirements specified in 4.9.1, report the average of the other two measured values, and report the filterability in this form: "Stage X filterability (R) AB.C". Alternatively, one more measurement may be carried out; if its measured value is within the measurement tolerance of the above two consistent measured values, discard the initially disputed measured value.
  • 4.8.3 If none of the three measured values meet the requirements specified in 4.9.1, the test must be repeated.
  • 4.8.4 If the filtration time exceeds 7200 s (2 h), report the test result as "not filterable".
• 5.8 Expression of results (Method Two): The test results for stage I filterability or stage II filterability are usually limited to 50, and are reported as "pass" or "fail". For a "pass" test result greater than 50, the numerical value of the test result may be given in parentheses; for a "fail" test result less than 50, the reproducibility is usually poor, and the numerical value of the test result is not given.
• 5.9 Validity of results (Method Two):
  • 5.9.1 If all three measured values are greater than 50, report as pass, and record the average of the three measured values, rounded to the nearest integer; if all three measured values are less than 50, report as fail.
  • 5.9.2 If among the three measured values two are greater than 50 and one is less than 50 but not lower than 40, report as pass, and state that only two results are greater than 50.
  • 5.9.3 If among the three measured values two results are less than 50 and one measured value is greater than 50, repeat the test.
  • 5.9.4 If the filtration time exceeds 7200 s (2 h), report the result as "not filterable".
• 6 Test report: The test report shall include at least the following:
  1. State that this standard is referenced.
  2. The type and complete information of the tested sample.
  3. The test results, and it shall be stated whether Method One (dry method) or Method Two (wet method) was used.
  4. State any differences from the specified test procedure, whether by agreement or for other reasons.
  5. Test date.

12. Normative references

• GB/T 3141 Industrial liquid lubricants ISO Viscosity classification (GB/T 3141—1994, eqv ISO 3448:1992)
• GB/T 4756 Petroleum liquids — Manual sampling (GB/T 4756—1998, eqv ISO 3170:1988)
• GB/T 6682 Water for analytical laboratory use — Specification and test methods (GB/T 6682—1992, neq ISO 3696:1987)
• GB/T 7305 Determination of water separability of petroleum and synthetic fluids
• ISO 13357-2:2005 (modified adoption)
• ISO 13357-1:2002 (modified adoption)

13. Source and verification

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14. Quick reference for questions and answers