GB/T 260-2016 Determination of water content in petroleum products — Distillation method

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Card type: Test method

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

• Standard number: GB/T 260—2016
• Chinese title: Determination of water content in petroleum products — Distillation method
• English title: Test method for water in petroleum products—Distillation method
• Replacement relationship: replaces GB/T 260—1977 "Determination of water in petroleum products"
• Adoption relationship: modified adoption using the redrafting method of ISO 3733:1999 "Determination of water content in petroleum products and bituminous materials — Distillation method" (MOD)
• Previous versions: GB/T 260—1961, GB/T 260—1977
• Publication/implementation: published on 2016-12-13, implemented on 2017-07-01

2. Scope of application and non-applicability

• Applicable to petroleum products, tar and its derivative products.
• Water content determination range: not greater than 25%.
• Samples with water content exceeding 25% can be determined, but their precision has not been investigated.
• If volatile water-soluble substances are present in the sample, they will be determined as water.
• Differences from ISO 3733:1999: this standard does not include the determination of water content in bituminous materials; the content on emulsified products in ISO 3733:1999 has also not been adopted.

3. Method principle

The test sample and a solvent immiscible with water are heated together under reflux; the solvent can carry out the water in the sample. The continuously condensed solvent and water are separated in the receiver, the water settles in the graduated receiver, and the solvent flows back into the distillation flask.

4. Reagents and materials (purity / preparation)

• General requirements: different extraction solvents are used according to different samples (see 8.3, refer to Table 3). The solvent should be dehydrated and filtered before use; determine the water content of the solvent according to steps 8.6 to 8.9, and the determination result should be "none".
• 5.1 Aromatic solvent, the following may be used:
  • a) Industrial grade or above xylene (mixed xylene);
  • b) A mixed solvent of industrial grade toluene with volume fraction 20% and industrial grade xylene (mixed xylene) with volume fraction 80%;
  • c) Petroleum fraction tested according to GB/T 6536, with a distillate amount at 125 ℃ not exceeding volume fraction 5%, and a distillate amount at 160 ℃ not less than volume fraction 20%, and a density at 20 ℃ not lower than 852 kg/m³.
• 5.2 Petroleum fraction solvent: tested according to GB/T 6536, with a distillation temperature at volume fraction 5% within 90 ℃ to 100 ℃, and a distillation temperature at volume fraction 90% below 210 ℃.
  • Note: Petroleum ether meeting GB/T 15894—2008, 90 ℃ to 120 ℃ may be selected, or petroleum ether with 90 ℃ to 120 ℃ may be blended in an appropriate proportion with No. 1 or No. 2 solvent naphtha meeting GB 1922—2006 to prepare a petroleum fraction solvent meeting the above requirements.
• 5.3 Paraffinic solvent, the following may be used:
  • a) Petroleum ether (light petroleum hydrocarbon), with a boiling point range between 100 ℃ and 120 ℃;
  • b) 2,2,4- trimethylpentane (isooctane), with purity above 95%.
• Table 3 Test samples and their matching extraction solvents:
  • Aromatic solvent → tar, tar products
  • Petroleum fraction solvent → fuel oil, lubricating oil, petroleum sulfonate, emulsified oil products
  • Paraffinic hydrocarbon solvent → lubricating grease

5. Apparatus and equipment

• 4.1 Overview: The apparatus includes a glass distillation flask, a graduated glass receiver, a reflux condenser and a heater. The distillation flask, receiver and condenser should be sealed and connected in an appropriate manner, preferably with ground-glass joints. Typical assembly diagrams are shown in Figure 1 and Figure 2.
  • Note: It is recommended that glass apparatus joints uniformly use 19/24# ground joint (the source text elsewhere has the expression "19/21# ground joint", requires confirmation against the source standard (source-text extraction)); other joint numbers meeting the determination precision requirements may also be used.
• 4.2 Distillation flask: short-neck glass container, the short-neck joint is suitable for connecting to the reflux tube of the receiver, the capacity is generally 500 mL, and containers of 1 000 mL and 2 000 mL may also be used.
• 4.3 Receiver: specifications are listed in Table 1. Select the distillation flask and receiver model according to the expected sample amount and water content. If the received water amount exceeds 25 mL, a 25 mL receiver with stopcock may be used, and the water exceeding the scale is put into a 10 mL graduated cylinder. 10 mL conical receivers are divided into precision conical and standard conical types; the 10 mL precision conical receiver is suitable for samples whose product specifications have trace indicators, with ten equal divisions below 0.3 mL; seven equal divisions are provided between 0.3 mL and 1.0 mL; each division between 1.0 mL and 10 mL is 0.2 mL (see Figure 3).
• 4.4 Condenser: a straight water condenser with a recommended length of 100 mm is recommended.
• 4.5 Heater: an electric heater may be used for the glass distillation flask; an electric heater equipped with magnetic stirring can prevent bumping of the solution.
• 4.6 Balance: sensitivity 0.1 g (the source text "0.18" is suspected to be source-text extraction noise, requires confirmation against the source standard (source-text extraction)).
• 4.7 Graduated cylinder:
  • 4.7.1 10 mL graduated cylinder: division value 0.2 mL.
  • 4.7.2 100 mL graduated cylinder: division value 1 mL.
• Table 1 Specification requirements for receivers (the source table source-text extraction is garbled; the following is the recognizable content, requires confirmation against the source standard (source-text extraction)):
  • Receiver volume 2 mL: scale range 0 to 2 mL, minimum division value 0.05 mL, maximum scale error 0.025 mL, bottom shape round;
  • Receiver volume 5 mL: scale range 0 to 5 mL, minimum division value 0.05 mL, maximum scale error 0.05 mL, bottom shape round;
  • Receiver volume 10 mL: scale range 0 to 0.3, >0.3 to 1, ≥1 to 10 mL, minimum division value 0.03, 0.1, 0.2 mL, maximum scale error 0.03, 0.05, 0.1 mL, bottom shape precision conical (see Figure 3);
  • Receiver volume 10 mL: scale range 0 to 1, >1 to 10 mL, minimum division value 0.1, 0.2 mL, maximum scale error 0.05, 0.1 mL, bottom shape standard conical;
  • Receiver volume 10 mL: scale range 0 to 10 mL, minimum division value 0.1 mL, maximum scale error 0.1 mL, bottom shape round;
  • Receiver volume 25 mL: scale range 0 to 1, ≥1 to 25 mL, minimum division value 0.1, 0.2 mL, maximum scale error 0.05, 0.1 mL, bottom shape conical;
  • Length of the graduated portion of the receiver: 85 to 105, 120 to 140, 120 to 110 (suspected source-text extraction), 120 to 140, 140 to 160 mm (correspondence requires confirmation against the source standard (source-text extraction)).
• Figure 1 Distillation apparatus with receiver without stopcock: 1— distillation flask, 2— receiver, 3— condenser.
• Figure 2 Distillation apparatus with receiver with stopcock: 1— condenser, 2— receiver, 3— distillation flask, 4— stopcock.
• Figure 3 10 mL precision conical receiver (unit is millimeters; the specific dimensions in the source text source-text extraction are unclear, requires confirmation against the source standard (source-text extraction)).

6. Recommended operating conditions

• Heat the distillation flask and adjust the boiling rate of the sample so that the distillation rate of the condensate in the condenser tube is 2 drops/s to 9 drops/s.
• Continue distillation until no more water is present in the distillation apparatus (except in the receiver), and the volume of water in the receiver remains constant within 5 min.
• If there is a water ring on the condenser tube, carefully increase the distillation rate, or turn off the circulation of cooling water for a few minutes.
• Insert loose cotton at the top of the condenser tube to prevent moisture from the atmosphere from entering; pass circulating cooling water through the condenser jacket.
• Magnetic stirring can effectively prevent bumping; glass beads or boiling aids may also be added to the distillation flask.

7. Sampling and sample preparation

• 7.1 Overview: Sampling is defined as all the steps required to obtain a representative test sample from a pipeline, tank or other system and place it in a laboratory test container (see Annex A).
• 7.2 Laboratory sample: Unless otherwise specified, sampling shall be carried out in accordance with GB/T 4756, GB/T 27867 or SH/T 0229. The amount of test sample is determined according to the expected water content, and it is required that the water yield should not exceed the upper scale limit of the receiver; unless the receiver has a stopcock, the water exceeding the scale may be put into a 10 mL graduated cylinder.
• 7.3 Preparation of the test sample: in addition to proceeding as specified in GB/T 4756, GB/T 27867 or SH/T 0229, it is also necessary to prepare according to the following steps:
  • 7.3.1 For friable solid samples, they must be completely ground and mixed uniformly, and the sample used for the test is to be obtained from this.
  • 7.3.2 Liquid samples must be mixed uniformly in the original container, and heated to mix uniformly if necessary. The mixing time, mixing intensity (speed) of the sample, and the height of the stirrer from the bottom of the sample container shall all be operated in accordance with Annex A, so that the sample meets the analysis requirements. Neither the volume of the sample nor the water content shall exceed the maximum values specified in Annex A.
  • Note: If there is doubt about the uniformity of the sample after mixing according to 7.3.1 or 7.3.2, when determining the sample, if the sample amount is compatible with the expected water content, the entire sample may be determined in one go; if the sample amount is too large to be determined in one go, then at least 3 test portions shall be taken, and the results of 3 determinations shall be recorded in the test report, with the average of the results serving as the result for the water content of the sample.
• Annex A (Normative Annex) Sample handling: contains A.1 overview, A.2 homogenization of the sample, A.3 verification of mixing time, A.4 transfer of the sample (for specific clauses see Annex A of the original text).

8. Analysis steps

• 8.1 Before testing the sample, it is necessary to mix uniformly according to the steps in 7.3.
• 8.2 According to the type of sample, take an appropriate amount of sample, accurate to ±1%, and transfer it into the distillation flask as required by 8.3 or 8.4.
• 8.3 For flowing liquid samples, measure an appropriate amount of sample with a graduated cylinder. Using one portion of 50 mL and two portions of 25 mL of the selected extraction solvent (see Chapter 5 and Table 3), rinse the graduated cylinder in portions, and transfer all of the sample into the distiller. After the sample is poured into the distiller or after each rinse, the graduated cylinder shall be completely drained.
• 8.4 For solid or viscous samples, weigh the sample directly into the distillation flask, and add the extraction solvent selected in 100 mL (see Table 3). For samples with low water content, the weighed sample amount needs to be increased, so the amount of extraction solvent also needs to be greater than 100 mL.
  • Note: When using the 10 mL receiver to test the sample, if the water content is greater than 10%, the sample amount may be reduced so that the amount of water distilled out does not exceed 10 mL.
• 8.5 If the sample being tested has a product specification requirement of "trace", it is recommended to use the 10 mL precision conical receiver (see Figure 3). The sample amount is 100 g or 100 mL, and the amount of solvent added is 100 mL.
• 8.6 Magnetic stirring can effectively prevent bumping, and glass beads or boiling aids may also be added to the distiller to reduce bumping.
• 8.7 Assemble the distillation apparatus according to Figure 1 or Figure 2, select an appropriate receiver by estimating the water content in the sample, and ensure the seal at the contact between vapor and liquid. The condenser tube and receiver need to be cleaned thoroughly to ensure that the distilled water does not stick to the tube wall and all flows into the bottom of the receiver. Insert loose cotton at the top of the condenser tube to prevent moisture from the atmosphere from entering. Pass circulating cooling water through the jacket of the condenser tube.
• 8.8 Heat the distillation flask, adjust the boiling rate of the sample so that the distillation rate of the condensate in the condenser tube is 2 drops/s to 9 drops/s. Continue distillation until there is no more water in the distillation apparatus (except in the receiver), and the volume of water in the receiver remains unchanged within 5 min. If there is a ring of water on the condenser tube, carefully increase the distillation rate, or turn off the circulation of cooling water for a few minutes.
• 8.9 After the receiver has cooled to room temperature, use a glass rod or polytetrafluoroethylene, or another suitable tool, to move the water adhering to the condenser tube and the walls of the receiver into the water layer. Read the water volume, accurate to the scale value.
• 8.10 If a new batch of solvent is used, it is necessary to determine the solvent required for the test according to the steps in 8.6 to 8.9, and the water content determination result shall be "none".

9. Qualitative and quantitative determination and calculation formulas

According to the method of measuring the sample, calculate the volume fraction of water in the sample φ (%) or the mass fraction w (%) according to formula (1), formula (2) or formula (3).

• Formula (1): φ = V₁ / V × 100%
• Formula (2): φ = V₁ / (m/ρ) × 100%
• Formula (3): w = V₁ρ* / m × 100%

Where:

• V —— the volume of the sample, in milliliters (mL);
• V₁ —— the water in the receiver when determining the sample, in milliliters (mL);
• m —— the mass of the sample, in grams (g);
• ρ —— the density of the sample 20 ℃, in grams per cubic centimeter (g/cm³);
• ρ* —— the density of water, taken as 1.00 g/cm³.

Note: If volatile water-soluble substances are present in the sample, they will also be determined in the form of water.

10. Precision

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

• 11.1 Repeatability r: For the same operator, using the same instrument, determining the same sample, the difference between two repeated determination results obtained shall not be greater than the value specified below or shown in Table 4.
  • When using the 10 mL precision conical receiver to determine water content, when the amount of water received in the receiver is 0.3 mL (inclusive) or less, the difference between the two determination results obtained shall not exceed one scale division of the receiver.
• 11.2 Reproducibility R: For different operators, in different laboratories, determining the same sample, the difference between two single and independent results obtained shall not be greater than the value shown in Table 4.
• Table 4 Precision (in milliliters):
  • Amount of water received 0.0 to 1.0: repeatability 0.1, reproducibility 0.2;
  • Amount of water received 1.1 to 25: repeatability 0.1 mL or 2% of the average amount of water received, whichever is greater; reproducibility 0.2 mL or 10% of the average amount of water received, whichever is greater.
  • Note: When using the 10 mL precision conical receiver to determine water content, for the precision when the amount of water received in the receiver is 0.3 mL (inclusive) or less, see 11.1.

11. Report

• 10.1 Report the water content result as volume fraction or mass fraction.
• 10.2 For samples of 100 mL or 100 g, if a receiver of 2 mL or 5 mL is used, report the water content determination result accurate to 0.05%; if a receiver of 10 mL or 25 mL is used, report the result accurate to 0.1%.
• 10.3 When using the 10 mL precision conical receiver, when the water content is less than (inclusive of) 0.3%, report the water content determination result accurate to 0.03%; when the water content is greater than 0.3%, report the result accurate to 0.1%. If the water content of the sample is less than 0.03%, report the result as "trace". If no water is present in the receiver after the apparatus is disassembled, report the result as "none".
• 12 The test report shall at least include:
  • a) indicate the number of this standard;
  • b) the type of product tested and related information;
  • c) the test results (see Chapter 10);
  • d) indicate any differences from the specified test steps due to agreement or other reasons;
  • e) the test date.

12. Normative references

• GB 1922—2006 Solvent naphtha for paints and cleaning
• GB/T 4756 Petroleum liquids — Manual sampling (GB/T 4756—1998, eqv ISO 3170:1988)
• GB/T 6536 Determination of distillation characteristics of petroleum products at atmospheric pressure
• GB/T 15894—2008 Chemical reagent — Petroleum ether (ISO 6353-3:1987, NEQ)
• GB/T 27867 Petroleum liquids — Automatic pipeline sampling (GB/T 27867—2011, ISO 3171:1988, IDT)
• SH/T 0229 Sampling method for solid and semi-solid petroleum products
• Reference: [1] ISO 3734:1997 Petroleum products — Determination of water and sediment in residual fuel oils — Centrifuge method

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