GB/T 266-1988 Determination of Engler viscosity of petroleum products

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Card type: Test method

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

• Standard number: GB/T 266-88
• Chinese title: Determination of Engler viscosity of petroleum products
• English title: Petroleum products—Determination of engler viscosity
• Replacement relationship: replaces GB 286-77
• Approval/implementation: approved by China Petrochemical Corporation 1988-07-27, implemented on 1989-06-01
• First issued: 1964 year 4 month
• Reference adoption: Soviet national standard ГОСТ 6258-52 "Method for determination of conditional viscosity of petroleum products"

2. Scope of application and non-applicability

• This standard specifies the method for determining viscosity with an Engler viscometer.
• This standard applies to the determination of the Engler viscosity of petroleum products.
• Not applicable: not provided in the available source.

3. Method principle

Engler viscosity is the ratio of the time required for a sample at a certain temperature to flow out of 200 mL from an Engler viscometer to the time required for distilled water at 20 ℃ to flow out the same volume (s) (i.e., the water value of the viscometer). During the test, the sample outflow should form a continuous line. The Engler viscosity at temperature t is denoted by the symbol E_t, and the unit of Engler viscosity is the conditional degree, represented by the symbol °E.

4. Reagents and materials (purity / preparation)

4.1 Apparatus

• 4.1.1 Engler viscometer (Figure 1): includes a container for the sample, a wooden stopper for plugging the outflow tube, and a metal tripod.
  • The inner container 10 for holding the sample is mounted in the outer container 12 used as a water bath or oil bath; both containers are made of brass.
  • The bottom of the inner container 8 is made spherical; the inner surface is polished and gold-plated.
  • The inner container is provided with a brass hollow convex cover, which has two openings 1 and 11 for inserting the wooden stopper and thermometer.
  • The wooden stopper 2 (Figure 2) is used to plug the outflow hole 6 of the apparatus.
  • Inside the inner container, three small pointed pins bent upward at right angles are installed at equal distances from the bottom on the wall, serving as indicators for controlling the oil level height and the levelness of the apparatus.
  • The outer container is provided with a stirrer 3 and a thermometer; the thermometer is fixed by a clip on the wall of the outer container.
  • The inner container is fixed in the outer container by three support rods and the outflow tube; the outflow tube is plugged by a wooden stopper passing through the central hole of the cover.
  • The wooden stopper is made of hard wood (boxwood and others); specifications are shown in Figure 2.
  • The iron tripod 9 consists of a ring and three long legs, two of which are provided with leveling screws 5.
  • Main dimensions of the Engler viscometer (mm, including tolerances):

    Part	Dimension	Tolerance
    Inner container inner diameter	106.0	±1.00
    Inner container height from bottom to enlarged part	70.0	±1.00
    Inner container depth of protruding bottom part	7.0	±0.10
    Inner container inner diameter of enlarged part	115.0	±1.00
    Inner container height of enlarged part	30.0	±2.00
    Inner container distance from the level of the pin tips to the lower edge of the outflow tube	52.0	±0.50
    Outflow tube total length	20.0	±0.10
    Outflow tube length of protruding part	3.0	±0.30
    Outflow tube inner diameter at the level of the container bottom	2.9	±0.02
    Outflow tube inner diameter at the lower end	2.8	±0.02

  • Each Engler viscometer shall have the viscometer name and the manufacturer's factory number or factory mark indicated on the surface of the outer container, and the viscometer serial number shall also be indicated.
  • The water value of the Engler viscometer shall be calibrated at least once every four months.
• 4.1.2 Thermometer: two in total, meeting the requirements for Engler viscosity thermometers in GB/T 514.
• 4.1.3 Receiving flask for Engler viscometer: two types (Figure 3), one with a neck graduation line at 100 mL; the other wide-mouthed with two graduation lines, indicating 100 mL and 200 mL. For each type of receiving flask, the capacity from the highest graduation line to the mouth shall be not less than 60 mL. The graduation line must be marked at 20 ℃, located in the middle of the narrow part of the neck. The inner diameter of the neck is 18±2 mm. Each receiving flask shall be marked with words such as "100 mL" or "200 mL", "+20 ℃", "for Engler viscometer", etc.
• 4.1.4 Electric heating device.
• 4.1.5 Pipette: 5 mL.
• 4.1.6 Stopwatch: graduation value 0.2 s.

4.2 Materials

• 4.2.1 Lubricating oil: kinematic viscosity at 50 ℃ is 20~60 mm²/s, flash point by open cup method not lower than 180 ℃.
• 4.2.2 Solvent naphtha: meets the specifications for rubber industry solvent naphtha in SH/T 0004.

5. Instruments and equipment

See 4.1 (Engler viscometer, thermometer, receiving flask, electric heating device, pipette, stopwatch).

6. Recommended operating conditions

• Outer container bath liquid: use water when the determination temperature is below 80 ℃; use lubricating oil when the determination temperature is 80~100 ℃.
• The bath liquid shall be preheated to slightly above the specified temperature.
• The sample temperature in the inner container is constant to ±0.2 ℃, maintained for 5 min.
• During the test, the liquid temperature in the outer container is constant to ±0.2 ℃.
• Water value determination temperature: 20 ℃; the water value of a standard viscometer should be equal to 51.1 s (original text is "511s", requires confirmation against the source standard (source-text extraction), according to 8 calculation example K20=51.1 s).

7. Sampling and sample preparation

• Before determining viscosity, filter the sample through a metal filter screen with at least 576 holes per square centimeter.
• If the sample contains water, add freshly calcined and cooled table salt, sodium sulfate, or granular anhydrous calcium chloride, shake, allow to settle, and then filter through the filter screen.
• Note: If the sample contains persistent bubbles, it is permitted to remove them by connecting the sample bottle to a vacuum pump under reduced pressure 10 min.

8. Analytical procedure

8.1 Determination of the water value of the viscometer (Article 6.1)

• Definition of water value: the time required for distilled water at 20 ℃ to flow out of 200 mL from the viscometer (s).
• Before determination, wash the inner container successively with petroleum ether (or diethyl ether), 95% ethanol, and distilled water, and blow dry with air.
• Place the short leg of the viscometer into the hole of the iron tripod and fix it with the fixing screw; insert a clean, dry wooden stopper into the upper hole of the outflow tube.
• The receiving flask shall be carefully washed beforehand successively with chromic acid cleaning solution, water, and distilled water.
• Pour freshly distilled distilled water (20 ℃) into the inner container until the tips of the three pins just emerge above the water surface; fill the outer container with water at the same temperature up to the enlarged part of the inner container.
• Rotate the adjusting screws of the iron tripod so that the tips of the three pins are at the same horizontal plane.
• Place an empty receiving flask under the outflow tube. Slightly lift the wooden stopper to let all water flow into the receiving flask (do not count the outflow time). The outflow tube must be filled with water, with a large drop hanging at the bottom end.
• Immediately insert the wooden stopper into the outflow tube, carefully pour the water from the receiving flask back into the inner container along a glass rod, taking care not to splash. Invert the empty receiving flask for 1~2 min to let the water drain completely, then place it back under the outflow tube.
• Both the water in the inner container and the liquid in the outer container must be thoroughly stirred: first stir the water by rotating the cover with the thermometer, then stir the temperature-maintaining liquid with the blade stirrer of the outer container.
• When the temperatures of both containers are equal to 20 ℃ (temperature difference within 5 min not exceeding 0.2 ℃) and the inner container is level, quickly lift the wooden stopper (it should automatically catch and remain lifted; pulling out the stopper is not allowed), and simultaneously start the stopwatch. Stop the watch immediately when the lower edge of the meniscus reaches the 200 mL ring mark of the receiving flask.
• The time for distilled water outflow 200 mL is measured continuously four times. When the difference between each result and the arithmetic mean is not greater than 0.5 s, take the arithmetic mean as the average outflow time of the first determination. Carry out another parallel determination with the same requirements. When the difference between the average outflow times of repeated determinations is not greater than 0.5 s, take the arithmetic mean of the two results as the instrument water value, symbol K20.
• The water value of a standard viscometer should be equal to 51.1 s (original text "511s", requires confirmation against the source standard (source-text extraction)). If the water value is not within this range, the instrument is not allowed to be used for viscosity determination.

8.2 Test procedure (Chapter 7)

• 7.1 Before each determination, carefully wash the inner container and outflow tube of the viscometer with filtered clean solvent naphtha, and blow dry with air. The inner container must not be wiped; only filter paper with trimmed edges may be used to absorb remaining droplets.
• 7.2 When determining the viscosity of the sample at the specified temperature, first tightly plug the outflow hole with the wooden stopper (do not press excessively, to avoid rapid wear of the stopper), and pour the sample preheated to slightly above the specified temperature (prepared according to Chapter 6) into the inner container; no bubbles should be generated in the sample. The poured oil level must be slightly above the tips of the pins.
• Pour water (for determination temperatures below 80 ℃) or lubricating oil (for determination temperatures 80~100 ℃) into the outer container of the viscometer, preheated to slightly above the specified temperature.
• Make the sample temperature in the inner container exactly reach the specified temperature, maintain for 5 min, and keep the sample temperature in the inner container constant to ±0.2 ℃. Record the liquid temperature in the outer container. During the test, keep the liquid temperature in the outer container constant to ±0.2 ℃ (stirring may be used, and slight heating with the electric heating device may be used if necessary).
• Slightly lift the wooden stopper to let excess sample flow down until the tips of the three pins just emerge above the oil surface. If too much has flowed out, add sample dropwise to the pin tips; no bubbles should remain in the oil.
• After covering the viscometer, place a clean, dry receiving flask under the outflow hole. Carefully rotate the cover with the thermometer around the wooden stopper to stir the sample with the thermometer.
• When the thermometer in the sample exactly reaches the specified temperature, maintain for 5 min (without stirring), quickly lift the wooden stopper, and simultaneously start the stopwatch. The lifted position of the wooden stopper shall be kept the same as when determining the water value (pulling out the stopper is not allowed).
• When the sample in the receiving flask exactly reaches the 200 mL mark (foam is not counted), immediately stop the stopwatch and read the sample outflow time, accurate to 0.2 s.
• Note ①: In arbitration tests, before each repeat test, clean the apparatus according to 7.1 and inject a portion of untested sample into the inner container.
• Note ②: When the results of two repeat determinations of fuel oil exceed the precision requirement, before conducting the third determination, the apparatus must be cleaned according to 7.1 and a portion of untested sample must be injected into the inner container.

9. Qualitative and Quantitative and Calculation Formula

The Engler viscosity E_t of the sample at temperature t, in units of degrees Engler, is calculated according to the following formula:

E_t = T_t / K20

Where:

• T_t—— the time required for the sample to flow out 200 mL from the viscometer at test temperature t, s;
• K20—— the water value of the viscometer, s.

Example: Viscometer water value K20 = 51.1 s. Suppose the time for fuel oil to flow out 200 mL from the viscometer at 80 ℃ is T80 = 472.8 s, then the Engler viscosity determination result of the fuel oil at 80 ℃ is: E80 = T80 / K20 = 472.8 / 51.1 = 9.2 degrees Engler.

10. Precision

Repeatability: The difference between two outflow times determined repeatedly by the same operator shall not exceed the following values:

11. Report

Take the arithmetic mean of the two repeat determination results as the Engler viscosity of the sample.

12. Referenced Documents

• GB/T 514 Technical conditions for liquid thermometers for petroleum product testing
• SH 0004 Rubber industry solvent oil (main text 4.2.2 written as SH/T 0004)

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