NB/SH/T 0850-2010 Determination of flow spread of lubricating greases for precision machinery and optical instruments

AI-translated method card — human verification pending. This is not an official translation of the standard. Unclear source values remain unverified; check the original standard and product certificate before use.

Card type: Test method

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

• Standard number: NB/SH/T 0850—2010
• Chinese full title: Determination of flow spread of lubricating greases for precision machinery and optical instruments
• English name: Spreading testing of lubricating greases for precision engineering and optical instruments
• Replacement relationship: not provided in the available source (the foreword only states modified adoption of DIN 58397.2-1983, and does not mention replacement of any standard)
• Adoption relationship: modified adoption of the German national standard DIN 58397.2-1983 "Determination of flow spread of lubricating greases for precision machinery and optical instruments"
• Main technical differences from DIN 58397.2-1983: this standard allows the use of filter paper meeting the type 103c requirements in standard GB/T 1914
• Publication/implementation: published on 2011-01-09, implemented on 2011-05-01
• Issuing authority: National Energy Administration
• Technical committee: Synthetic Grease Subcommittee of the National Technical Committee for Standardization of Petroleum Products and Lubricants
• Drafting organization: Lubricant Chongqing Branch of China Petroleum & Chemical Corporation
• Main drafters: Zhang Ying, Luo Yulan

2. Scope of application and non-applicability

• 1.1 This standard specifies a method for determining the flow spread of lubricating greases for precision machinery and optical instruments.
• 1.2 It is applicable to the determination of the flow spread performance of lubricating greases for precision machinery and lubricating greases for optical instruments with a cone penetration within 130~385 (unit: 0.1mm).
• 1.3 This standard involves certain hazardous materials, operations and equipment, but does not provide recommendations for all safety issues related thereto; users should establish appropriate safety and precautionary measures before use and formulate corresponding management systems.
• Non-applicable scope: not provided in the available source.

3. Method principle

Take a certain volume of the lubricating grease sample to be tested, maintain its shape with a specific aluminum ring, place it on the specified filter paper, and at the specified test temperature, after a certain period of time, measure the diffusion area of the oil in the sample on the filter paper in three stages. Plot the oil-impregnated area after diffusion against time, determine from the curve the time when the oil diffusion area is 20cm², and calculate the flow spread index value.

4. Reagents and materials (purity / preparation)

• 5.2.1 Aluminum ring: aluminum alloy No. 2A11, all surfaces smooth, top and bottom faces flat, see schematic diagram 1 (the dimensions marked in the original figure 1 are suspected to be φ20, φ30, requires confirmation against the source standard (source-text extraction)).
• 5.2.2 Scraper.
• 5.2.3 Straight ruler: graduation value 1mm or smaller.
• 5.2.4 Filter paper: qualitative filter paper meeting the type 103c requirements in GB/T 1914, diameter φ90mm.
• 5.2.5 Lubricating grease worker: meeting the requirements of GB/T 269.
• 5.2.6 Rectangular coordinate paper: unit mm.
• 5.2.7 Glass watch glass: diameter 100mm (the original text is "100xm omm", requires confirmation against the source standard (source-text extraction)).
• 5.2.8 Clock.
• 5.2.9 Compass.
• Reagent purity/preparation: not provided in the available source.

5. Instruments and equipment

• 5.1.1 Constant-temperature oven: temperature can be controlled within the range of 23±2℃, 40℃, 70℃ (the original text "23 [unreadable sign]24, 40 3, 70C 5[unreadable character]", temperature tolerance requires confirmation against the source standard (source-text extraction)).
• Other instruments are given under the materials item in clause 4 (the original text lists the aluminum ring, scraper, straight ruler, filter paper, lubricating grease worker, rectangular coordinate paper, glass watch glass, clock, and compass under "5.2 Materials").

6. Recommended operating conditions

• Test temperature: may be selected according to the maximum service temperature or diffusion performance of the sample; if both are unknown, it is best to test at the maximum permissible temperature.
• When the test is completed within 30min, a lower test temperature should be selected for the test.
• When testing at the maximum test temperature, if after the sample has been placed in the oven for more than 24h, no trace of oil stain diffusion is observed on the filter paper outside the area covered by the aluminum ring, the test shall be stopped.
• Constant-temperature oven temperature control range: 23±2℃, 40℃, 70℃ (tolerance requires confirmation against the source standard (source-text extraction)).

7. Sampling and sample preparation

• 6.2 Place the lubricating grease to be tested into the lubricating grease worker and work 60 strokes in accordance with GB/T 269.
• 6.3 Place the aluminum ring on the filter paper, align the outer circle with the drawn concentric circle of diameter 30mm, keep the filter paper flat, and use a scraper to fill the aluminum ring with lubricating grease that has been treated through 6.2 strokes, avoiding the introduction of air bubbles during sample loading. Scrape off excess lubricating grease sample along the direction of the upper edge of the aluminum ring so that the surface of the lubricating grease sample in the aluminum ring is flush with the surface of the aluminum ring. During the process of adding lubricating grease, the aluminum ring must not move relative to the filter paper.
• 6.4 For the determination of lubricating grease samples, in accordance with 6.1~6.3, prepare at least three specimens. For arbitration testing, prepare 5 specimens.
• 6.5 Place the aluminum ring into the watch glass, and during the placement process take care that the aluminum ring does not move relative to the filter paper.

8. Analytical procedure

• 6.1 First fold the filter paper in half, then unfold it, and with the intersection of the two mutually perpendicular creases as the center, use a compass to draw three concentric circles on the filter paper with diameters 30mm, 40mm (the original text "20h5omm", requires confirmation against the source standard (source-text extraction)), as the critical lines for oil stain spreading.
• 6.6 Place the prepared specimens symmetrically in the middle of the oven that has been brought to the test temperature, and start timing.
• 6.7 Observe the diffusion of the oil stain on the filter paper. When the oil stain diffuses to between the aluminum ring and the second concentric circle (φ=40mm), make a corresponding mark at the crease of the filter paper and record the time taken t₁. When the oil stain diffuses to between the second concentric circle and the third concentric circle, make a corresponding second mark at the crease of the filter paper and record the time taken t₂. When the oil stain diffuses beyond the second mark by at least 5mm and is less than 5mm from the edge of the filter paper, make a corresponding third mark at the crease of the filter paper and record the time taken t₃. During all marking operations, movement of the aluminum ring relative to the filter paper should be avoided; after the first and second marks are made, the specimen should immediately be returned to the oven to continue the test.
• 6.8 After the test is completed, remove the specimen from the oven and cool to room temperature. Remove the aluminum ring together with the lubricating grease sample from the filter paper, and scrape off the residual lubricating grease on the filter paper with a sharp knife. Use a straight ruler to measure the major axis a and minor axis b of the ellipse formed by the four vertices of each mark, to the nearest 0. (the original text is truncated, requires confirmation against the source standard (source-text extraction)).

9. Qualitative and quantitative determination and calculation formulas

• 7.1 Based on the measured data, calculate the diffusion area of the oil stain A according to formula (1):
  • A = π × (a × b) / 4 ………………(1)
  • Where: A—— diffusion area of the oil stain, cm²; π—— pi; a—— major axis of the oil stain; b—— minor axis of the oil stain (unit not provided in the available source, requires confirmation against the source standard (source-text extraction)).
• 7.2 Based on the measured area A and the corresponding time t, plot a curve of area against time on rectangular coordinate paper (see Figure 2). From the curve, determine the time when the area is 20cm² (unit: hours), substitute into formula (2) to obtain the flow spread index Sₚ of the lubricating grease (rounded to an integer).
  • 100 / Sₚ = ………………(2) (the content on the right side of the original formula is missing, requires confirmation against the source standard (source-text extraction))
• 9.1 Take the average of the Sₚ values from three (or five) determinations, and use the formula Sₚ = 190 (as in the original text, suspected to be an incomplete formula, requires confirmation against the source standard (source-text extraction)) to calculate the flow spread performance index Sₚ of the sample.

10. Precision

• 8.1 For the same operator, using the same instrument, under the same operating conditions, the results of repeated determinations on the same sample shall not exceed the qₙ value given in Table 1, with a confidence level of 95%. (The original text "confidence level stated as 93%" contradicts 95% of 8.2, requires confirmation against the source standard (source-text extraction))
• 8.2 For different operators in different laboratories determining the same sample, the results obtained shall not exceed the value given in Table 1, with a confidence level of 95%.
• 8.3 If any of several parallel determinations does not conform to the precision requirements, the entire test shall be redone.
• Table 1 Range of repeatability qₙ and reproducibility qₙ (the table data in the original text are incomplete, only fragments such as "3 / 5 / ±13% / ±40% / ±20%" are visible, requires confirmation against the source standard (source-text extraction))
• Repeatability and reproducibility qₙ are calculated according to formula (3):
  • qₙ = K × S ………………(3)
  • Where: K—— statistical coefficient at the stated confidence level; S—— standard deviation, for n determinations, calculated according to formula (4).
• Table 2 Values of K (the table data in the original text are incomplete, only n=3, 5 corresponding to 2.48, 1.24, etc. are visible, requires confirmation against the source standard (source-text extraction))
• 8.4 Calculation example:
  • Sₚ₁=42, Sₚ₂=38, Sₚ₃=46, Sₚ₄=30, Sₚ₅=31, n=5
  • ΣSᵢ² = 42²+38²+46²+30²+31² = 7185
  • (ΣSᵢ)² = (42+38+46+30+31)² = 34965
  • S = √[(7185 - 34965/5) / (5-1)] (the original formula is incomplete, requires confirmation against the source standard (source-text extraction))
  • S = 6.91 ≈ 7

11. Report

• 9.1 Take the average of the Sₚ values from three (or five) determinations, and use the formula Sₚ = 190 (as in the original text, requires confirmation against the source standard (source-text extraction)) to calculate the flow spread performance index Sₚ of the sample.
• 9.2 Report the test results in the following format:
  • 9.2.1 Flowability index NB/SH/T 0850-Sₚ-test result-test temperature
    • Example: NB/SH/T 0850-Sₚ-36-70℃, indicating that according to NB/SH/T 0850 at the test temperature of 70℃, the flowability index of the specimen is 36.
  • 9.2.2 If the specimen at the highest test temperature, 24h still has no oil diffusion on the filter paper outside the aluminum ring, the result is reported in the following format:
    • Example: Flowability index NB/SH/T 0850 Sₚ-no flowability-70℃.

12. Normative references

• GB/T 269 Standard test method for cone penetration of lubricating grease and petrolatum (undated, latest version applies)
• GB/T 1914—1993 Chemical analytical filter paper (dated reference)

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 Q&A