GB/T 8019-2025Determination of gum content in fuels — Jet evaporation (English PDF)

1.2 This Standard specifies the determination method for the insoluble part of

n-heptane in non-aviation fuel residues.

1.3 This Standard adopts the units of International System of Units (SI).

1.4 This Standard involves certain hazardous materials, operations and

equipment, but it does not intend to make recommendations on all related safety issues. Therefore, it is necessary for users to establish appropriate safety and protection measures and determine an applicable management system before using this Standard. For special warning statements, see 6.4, 7.2 and 8.2.1 for details.

6.8 Thermometer: It shall meet the technical requirements of the thermometer

No. GB-29 in GB/T 514.

6.9 Graduated cylinder: 50 mL ± 0.5 mL in capacity.

6.10 Transferring tool: Brazier-head stainless-steel tweezers or stainless-steel

pliers, which are used to take out the beaker and the conical adapter.

9.1 Assembly of air jet apparatus

9.1.1 Assemble the air jet apparatus as shown in Figure 1. Adjust the air flow rate at the outlet of the test device to 600 (mL/s) ± 90 (mL/s) at room temperature. Check whether the air flow rates at the remaining outlets are consistent.

Note: The reading of each outlet at normal temperature and pressure of 600 (mL/s) ± 90 (mL/s) will ensure that the output is 1 000 mL/s ± 150 mL/s at a temperature of 155 °C ± 5°C.

9.1.2 Heat the evaporation bath (see 6.4), until the temperature of the bath

reaches 160 °C ~ 165 °C; introduce air into the apparatus, until the flow rate of each outlet reaches the flow rate that is required in 9.1. Use a thermometer (see 6.8) to measure the temperature of each hole. The temperature-sensitive bubble of the thermometer shall be inserted into the bottom of the beaker in the hole. This method does not apply to any hole whose temperature exceeds the range of 150 °C ~ 160 °C. in millimeters 10.1.2 A method to calibrate the air flow is to separate the calibrated flowmeter from the apparatus that is described in 6.5, and directly detect the flow of each outlet under normal temperature and pressure. To ensure the accuracy of the data, the back pressure of the flowmeter shall be less than 1 kPa.

10.1.3 Alternatively, another method of calibrating air flow is to measure and

adjust the corresponding total air flow that is supplied to all outlets. The total air flow is equal to the air flow of each outlet multiplied by the number of outlets (for example, if the apparatus has 5 holes, and the measured total flow is 3 000 mL/s, that is, the flow of each hole is 600 mL/s). When the total flow rate that is supplied to all outlets reaches an appropriate value after testing, compare the relative flow rate of each hole, to check whether it is consistent and meets the requirements in 10.1.1.

10.2 Steam flow correction

10.2.1 Check or calibrate the steam flow to ensure that all outlets reach 1 000 (mL/s) ± 150 (mL/s) under normal temperature and pressure. Refer to the manual of the apparatus to complete the steam flow calibration process.

10.2.2 A method to calibrate the steam flow is to connect a copper tube to the steam outlet and extend the copper tube into a mass-weighed 2 L graduated cylinder that contains crushed ice. Let the steam be discharged into the graduated cylinder for about 60 seconds. Adjust the position of the graduated cylinder, so that the end of the copper tube is immersed in water for less than

11.7 The beaker that contains the residue of motor gasoline shall be tested

according to the steps that are described in 11.8 ~ 11.12; the remaining beakers can be taken back for cleaning for reuse.

If a retained sample of the original finished gasoline is used for the reference test, the qualitative evidence of the contamination of motor gasoline can be obtained by weighing the residue. This reference test is important, because motor gasoline contains artificially added non-volatile substances. To prove the contamination, further research is required.

11.8 For non-aviation fuels whose unwashed gum content is less than 0.5

mg/100mL, it's unnecessary to perform this part of the washing step, nor to follow the steps of 11.9 ~ 11.12, because the solvent washed gum content is always less than or equal to the unwashed gum content. If the unwashed gum content is not less than 0.5 mg/100mL, add 25 mL of n-heptane to each beaker that contains the residue and rotate it gently for 30 s; let the mixture stand for 10 min. Process the tared beaker in the same way.

11.9 Pour out the n-heptane solution carefully, to prevent any loss of solid

residue.

11.10 Use the second 25 mL n-heptane; extract again according to the steps

that are described in 11.8 and 11.9. If the extract is colored, perform the third extraction again. Do not extract more than 3 times.

Z -- mass of the tared beaker that is recorded in 11.12, in grams (g);

13.2 For results, of which the non-aviation fuel solvent washed gum or

unwashed gum content is greater than or equal to 0.5 mg/100mL, report the solvent washed gum or unwashed gum content results, and round off the value according to GB/T 8170, to the nearest 0.5 mg/100mL; for results less than 0.5 mg/100mL, report as "< 0.5 mg/100mL". If the unwashed gum content is less than 0.5 mg/100mL, report the solvent washed gum content as "< 0.5 mg/100mL” as well.

13.3 For all samples, if a filtration step (see 11.4) is carried out before evaporation, indicate the words "after filtration" after the value of the gum content result.

14.1 Precision

See 14.1.1 and 14.1.2, as well as the curve in Figure 2, for the precision that is obtained from the statistical test results between laboratories (95% of confidence level).

Note: The precision of solvent washed gum content and unwashed gum content that is given in this method is statistically researched and measured between laboratories in 1997 with refined motor gasoline (including products that contain alcohol and ether oxygen-compounds and sediment inhibitor additives); the precisions of solvent washed gum content and unwashed gum content are respectively based on samples that contain 0 ~ 15 mg/100mL and 0 ~ 50 mg/100mL of gum content.

14.1.1 Repeatability (r): The difference between the results of two tests that are

performed on the same sample by the same operator using the same instrument under the same operating conditions. For aviation gasoline, the existent gum content shall not exceed the value that is specified by Formula (5);

for jet fuel, the existent gum content shall not exceed the value that is specified by Formula (6); for motor gasoline, the unwashed gum content shall not exceed ......

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