GB/T 509-1988 Determination of Existent Gum in Engine Fuels

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/T 509-88
• Chinese title: Determination of Existent Gum in Engine Fuels
• English title: Engine fuels—Determination of existent gum
• Replacement relationship: replaces GB 509-77
• First issued: 1965 year 1 month (see additional notes)
• Reference adoption: Soviet national standard ГОСТ 1567-56 "Determination of Gum in Engine Fuels" (see additional notes)
• UDC number: UDC 885.52 (as in the source text, requires confirmation against the source standard (source-text extraction))

2. Scope of application and non-applicability

• This standard specifies a method for determining the gum formed when fuel evaporates under the test conditions.
• This standard applies to gasoline, kerosene and diesel fuel.
• Not applicable: not provided in the available source.

3. Method principle

A 25mL test portion is evaporated under specified conditions of apparatus, temperature and air flow, and the resulting residue is weighed and expressed as milligrams of existent gum per 100mL of test portion (mg/100mL).

4. Reagents and materials (purity / preparation)

• Benzene: chemically pure.
• Acetone: chemically pure.
• Ethanol-benzene mixture: prepared from 95% ethanol (chemically pure) and benzene (chemically pure) in a volume ratio of 1:4.
• Sodium sulfate: chemically pure.
• Material: mineral oil, open-cup flash point not lower than 310℃.

5. Apparatus and equipment

• Oil bath (see figure): oval steel container 6, height about 200mm, major axis about 250mm, minor axis about 150mm. It is provided with a removable iron bath lid 5; under the lid there are two recesses 8 and 10 for placing beakers and a copper or brass coil 7, the coil having a total length of about 4.5m and an internal diameter of 6—8mm. One end of the coil 4 emerges beside the lid surface for introducing air; the other end 2 emerges at the center of the lid and is connected to a removable ground-glass three-way tube 3, through which air is supplied to the beaker by an air delivery tube. The air delivery tube has an internal diameter of about 6mm, each end faces the center of a recess, and is 50±5mm from the bottom of the recess. The bath lid also has two openings 9 and 1 for inserting a thermometer and a contact thermometer. The outer surface of the oil bath is insulated with an asbestos layer. The oil bath is equipped with an electric heating device capable of heating the oil in the bath to 150, 180 and 250℃, and of maintaining the temperature constant during the test period.
• Tall-form glass beaker without spout: capacity 100mL, outer diameter 47—48mm, height 85±2mm.
• Graduated cylinder: 25mL; or pipette: 25mL.
• Flowmeter: graduated to indicate an air flow rate of 60L per minute. Calibrated at least once every 300 tests.
• Air filter: containing cotton and glass beads.
• Thermometer: 0—360℃; optionally the open-cup flash point 1 thermometer of GB/T 514 may be used.
• Blower, air compressor, or air supply header: required to be capable of supplying the air flow rate needed for the test.
• Electric hot plate: with autotransformer.
• Chrome-plated crucible tongs.

6. Recommended operating conditions

• Oil bath temperature: 150±5℃ when determining gasoline; 180±5℃ when determining kerosene; 250±5℃ when determining diesel fuel.
• Contact thermometer setting: adjusted to 150℃ when determining gasoline; adjusted to 180℃ when determining kerosene; adjusted to 250℃ when determining diesel fuel.
• The thermometer mercury bulb is 40—50mm from the lid surface.
• Air flow rate: the initial rate shall be 20±2L per minute; during the first 8min when testing gasoline, or during the first 20min when testing kerosene or diesel fuel, it is gradually increased to 55±5L per minute and maintained until evaporation of the test portion is complete.
• The lower end of the air delivery tube is 30±5mm from the surface of the test portion.

7. Sampling and test portion preparation

• Filter the test portion with filter paper; if the test portion contains obvious traces of water, first add freshly calcined sodium sulfate to the test portion, shake for 10—15min, and then filter.
• Measure 25mL of test portion in two portions using a graduated cylinder or pipette.

8. Analytical procedure

• Preparation:
  • Pour an appropriate amount of mineral oil into the oil bath, such that after the bath lid is placed and the bath is heated to the test temperature, the oil bath is filled.
  • Insert the thermometer into the opening in the bath lid with a cork so that the mercury bulb is 40—50mm from the lid surface; if necessary, insert the contact thermometer into the other opening in the bath lid.
  • Before the test, the beaker used for determining existent gum must be carefully washed with any one of the solvents in Chapter 5. Then, on the oil bath preheated to the specified temperature, place the beaker in a recess for 15min, then place the beaker in a desiccator to cool for 30—40min, and then weigh the beaker to the nearest 0.0002g. Repeat the drying and weighing of the beaker until the difference between consecutive weighings does not exceed 0.0004g.
  • On the oil bath, the end of the coil that introduces air shall be connected to the air supply through a flowmeter and an air filter containing cotton.
• Test procedure:
  • 7.1 Measure 25mL of test portion in two portions using a graduated cylinder or pipette, respectively transfer them into beakers prepared as in 6.4, and then place the beakers in the oil bath recesses heated to the specified temperature. Thereafter, place the three-way tube at the end of the coil at the center of the bath lid, requiring the lower end of the air delivery tube to be 30±5mm from the surface of the test portion.
  • 7.2 When air is passed into the two beakers, the initial rate indicated by the flowmeter shall be 20±2L per minute. During the first 8min when testing gasoline, or during the first 20min when testing kerosene or diesel fuel, the air supply rate is required to be gradually increased to 55±5L per minute, while taking care not to cause splashing of the test portion. The above air supply rate shall be maintained until evaporation of the test portion is complete. Evaporation is considered complete when oil vapor stops escaping and the bottom and walls of the beaker show a dry residue or an oily residue that no longer decreases.
  • After evaporation is complete, continue passing air for 15—20min (gasoline and kerosene) or 30min (diesel fuel), then remove the beaker, place it in a desiccator to cool for 30—40min, and then weigh to the nearest 0.0002g. After weighing, place the beaker back into the oil bath recess, and with the same air rate and specified temperature as above, pass air again for 15—20min (gasoline and kerosene), or stop the air supply and dry at 250℃ for 30min (diesel fuel). Thereafter, place the beaker again in a desiccator to cool for 30—40min and then weigh. Repeat this treatment of the beaker containing gum until the difference between consecutive weighings does not exceed 0.0004g.
  • Note: After each operation, the beaker should be immediately washed with ethanol-benzene mixture to remove residue in the beaker.

9. Qualitative and quantitative determination and calculation formula

The existent gum X (mg) contained in the 100mL test portion is calculated according to the following formula:

X = (m₂ − m₁) × 100 / 25 = 4 (m₂ − m₁)

Where:

• m₂: mass of gum and beaker, mg;
• m₁: mass of beaker, mg;
• 25: volume of test portion, mL.

10. Precision

• 8.1 In the determination of existent gum in gasoline and kerosene, the difference between two results obtained by the same operator in repeat determinations shall not exceed the following values:

• 8.2 In the determination of existent gum in diesel fuel, the difference between two results obtained by the same operator in repeat determinations shall not exceed the following values:

11. Report

• 10.1 Take the arithmetic mean of two results from repeat determinations as the existent gum content of the test portion. The determination result shall be expressed as an integer.
• 10.2 When the existent gum content is less than 2mg/100mL, it is considered none.

12. Referenced documents

• GB/T 514 Technical conditions for liquid thermometers for petroleum product testing

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