GB/T 6531-1986 Determination of sediment in crude petroleum and fuel oils (extraction method)

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: GB 6531-86
• Chinese full title: Determination of sediment in crude petroleum and fuel oils (extraction method)
• English name: Crude petroleum and fuel oils—Determination of sediment—Extraction method
• Replacement relationship: not provided in the available source
• Adoption relationship: This standard is equivalent to international standard ISO 3735—1975 "Determination of sediment in crude petroleum and fuel oils (extraction method)"
• Issued / implemented: issued by the National Bureau of Standards 1986-06-25, implemented 1987-06-01

2. Scope of application and non-applicability

• Applicable to the determination of sediment content in crude petroleum and fuel oils by toluene extraction.
• Not applicable: not provided in the available source.

3. Method principle

Place the sample in a thimble of refractory porous material and extract with hot toluene until the residue reaches constant weight. Express the amount of residue as a mass percentage and report it as "extraction method sediment".

4. Reagents and materials (purity / preparation)

• Toluene: conforming to GB 684 "Toluene", chemically pure, or GB 3406 "Petroleum toluene" 2 grade.
• Safety note (original text): Toluene is flammable; keep away from heat sources, sparks and open flames. Toluene is toxic; special care must be taken to avoid inhaling its vapor and to protect the eyes. Keep containers closed. Use adequate ventilation during use. If spilled, absorb with sand or diatomaceous earth.
• Preparation of other reagents: not provided in the available source.

5. Apparatus and equipment

• 5.1 Extraction apparatus (see Figure 1 and Figure 2), consisting of the following components:
  • 5.1.1 Condenser: a metal coil approximately 25 millimeters in diameter and approximately 50 millimeters long. The coil should be welded to the cover, and its end should extend beyond the cover. This cover should fit properly on the conical flask, see Figure 1. The coil is made of stainless steel, galvanized iron sheet, tinned copper tube or tinned brass tube with an outer diameter of 5~8 millimeters and a wall thickness of 1.5 millimeters. If the coil is made of tinned copper tube or brass tube, the thickness of the tin coating shall be at least 0.075 millimeters. The coil is used for cooling purposes and its surface area is approximately 115 square centimeters (original text "115 centimeters combined", requires confirmation against the source standard (source-text extraction)).
  • 5.1.2 Extraction thimble: made of refractory porous material, with a pore size index of 10–16 micrometers, and a minimum permeability [air flow rate at a pressure of 100 pascals (1 millibars)] of 1.7 meters per square meter per thousand seconds (10.2 centimeters per square centimeter per minute). Diameter is 25 millimeters, height is 70 millimeters, and weight is 15–17 grams. The thimble shall be suspended from the condenser coil by a basket so that it hangs midway between the surface of the extraction solvent and the bottom of the condenser coil (original text "of the", requires confirmation against the source standard (source-text extraction)).
  • 5.1.3 Thimble basket: shall be made of corrosion-resistant platinum, stainless steel, nickel-chromium alloy or similar material, and shall meet the requirements of Figure 2.
  • 5.1.4 Water cup: when the sample has a high water content, a water cup shall be used (see Figure 1b). The cup shall be made of glass, conical, approximately 20 millimeters in diameter, 25 millimeters deep, and approximately 3 milliliters in capacity. A glass hook shall be fused to the side edge of the cup, and the shape of the hook shall be such that when the hook is hung on the condenser, the cup edge shall be level with the water (original text "the cup edge shall be level with the water", requires confirmation against the source standard (source-text extraction)).
  • Suspension method: In this method, the thimble basket is suspended from the bottom of the condenser coil with metal wire (see Figure 1a), or as shown in Figure 1b, the metal wire is tied to a hook on the underside of the condenser cover.
• 5.2 Heat source: suitable for vaporizing toluene, preferably an electric hot plate.
• Figure 2 Basket-type thimble support: a metal wire support; b slat support; all joints silver-brazed; the dimensions in the figure include 20, 53, -0.6, etc. (original figure note, specific correspondence requires confirmation against the source standard (source-text extraction)).

6. Recommended operating conditions

• Extraction heating: add 200~250 milliliters of toluene to the conical flask and heat for extraction.
• Extraction endpoint: when the solvent dripping from the thimble becomes colorless, continue extraction for 30 minutes.
• Extraction rate: ensure that the extraction rate is such that the liquid level of the oil and toluene mixture in the thimble is not higher than 20 millimeters below the top edge of the thimble.
• Drying conditions: dry in an oven at 115~120 ℃ for 1 hours.
• Cooling conditions: cool in a desiccator without desiccant for 1 hours.
• Weighing accuracy: thimble weighed to the nearest 0.1 milligrams; sample weighed to the nearest 0.01 grams.
• Repeated extraction dripping time: allow the solvent to drip from the thimble for at least 30 minutes, but not more than 75 minutes.

7. Sampling and sample preparation

• 4.1 Sampling: the sediment in crude petroleum and fuel oils is unevenly dispersed. To ensure that the sample is well representative, before pouring the sample into the extraction thimble, the sample should be shaken vigorously so that all the sediment in the sample can be uniformly dispersed in the oil. Viscous samples may be heated appropriately to facilitate uniform mixing.
• 4.4 After the sample has been thoroughly mixed, immediately pour about 10 grams into the thimble, weighed to the nearest 0.01 grams.

8. Analysis procedure

• 4.2 A new extraction thimble shall be used for arbitration tests. For routine tests, the thimble may be reused. The constant weight value of the thimble after the previous determination may be used as the pre-extraction for the next determination. When a large amount of accumulated sediment on the thimble would affect the determination result, the thimble may be heated to dark red (preferably using an electric furnace) to remove combustible parts. However, a thimble that has been heat-treated must be pre-extracted.
• 4.3 Before a new thimble is used, wipe its outer surface with No. 180 sandpaper; then tap all parts of the thimble with a rigid brush or a small wooden stick with a rubber tip to remove all loose material. Pre-extract with toluene, allowing the solvent to drip from the thimble for at least 1 hours, then dry the thimble in an oven at 115~120 ℃ for 1 hours, then cool in a desiccator without desiccant for 1 hours, and weigh to the nearest 0.1 milligrams. Repeat the extraction until the difference in thimble weight after two consecutive extractions is not greater than 0.2 milligrams.
• 4.4 After the sample has been thoroughly mixed, immediately pour about 10 grams into the thimble, weighed to the nearest 0.01 grams. Place the thimble in the extraction apparatus, add 200~250 milliliters of toluene to the conical flask, and heat for extraction. When the solvent dripping from the thimble becomes colorless, continue extraction for 30 minutes. Ensure that the extraction rate is such that the liquid level of the oil and toluene mixture in the thimble is not higher than 20 millimeters below the top edge of the thimble.
• 4.5 When the sample has a high water content, the apparatus shown in Figure 1b shall be used. In this procedure, the water in the sample forms an azeotrope with toluene and is extracted and collected in the water cup. The water is separated in the lower layer, and the toluene layer overflows into the thimble. If the water cup becomes full of water, cool the apparatus, pour off the water, and continue the test.
• 4.6 After extraction is complete, dry the thimble in an oven at 115~120 ℃ for 1 hours, cool in a desiccator without desiccant for 1 hours, and weigh to the nearest 0.1 milligrams.
• 4.7 Repeat the extraction, allowing the solvent to drip from the thimble for at least 30 minutes, but not more than 75 minutes. Dry, cool and weigh the thimble as described in 4.6. If necessary, repeat the extraction for another 30 minutes until the difference in thimble weight after two consecutive extractions is not greater than 0.2 milligrams.

9. Qualitative and quantitative determination and calculation formula

• 5.1 The mass percentage of sediment in the sample X (%) is calculated according to formula (1):

  X = A / B × 100 ...... (1)

  Where: A—— sediment weight, grams; B—— sample weight, grams.

• 5.2 The result is calculated to the nearest 0.01%, as the mass percentage of extraction method sediment.

• Note: If the sediment value is reported on a volume percentage basis, calculate the volume of sediment and the percentage of the sediment volume relative to the original sample volume. When the main part of the sediment is sand (silicon dioxide, density 2.32) and a small amount of other naturally occurring substances (density less than sand), the assumed density 2.0 shall be used for the obtained sediment (original text "assumed density", requires confirmation against the source standard (source-text extraction)). To obtain the volume percentage of sediment, multiply the mass percentage of sediment by the 20 ℃ density of the crude oil (if known, use 0.85) and then divide by 2.0.

  Volume % = mass percentage of sediment / 2.0 × [crude oil density or 0.85 (if unknown)]

10. Precision

Use the following provisions to judge the reliability of test results (95% confidence level).

• 6.1 Repeatability: the difference between two results obtained consecutively by the same operator shall not exceed the following value:

  0.017 + 0.2555·S ...... (2)

  Where: S—— the mean of the two determination results, %.

• 6.2 Reproducibility: the difference between two results submitted by different operators in different laboratories shall not exceed the following value:

  Original formula missing (source-text extraction only "Where: — the mean of the two specified results, %" is seen, requires confirmation against the source standard (source-text extraction)).

  Note: The precision of this method was obtained statistically from interlaboratory test results in the range 0~0.4 (the range used to establish precision is unclear in the source transcription; verify its limits against the original).

11. Report

• Report as "extraction method sediment", expressed as a mass percentage, with the result calculated to the nearest 0.01% (see 1, 5.2).
• Other reporting requirements: not provided in the available source.

12. Referenced documents

• GB 684 "Toluene"
• GB 3406 "Petroleum toluene" 2 grade
• ISO 3735—1975 "Determination of sediment in crude petroleum and fuel oils (extraction method)" (equivalent adoption)

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