Determination Method for Pour Point of No. 0 Diesel Fuel
No. 0 diesel fuel belongs to light diesel oil, which is a mixture of complex hydrocarbons (with approximately 10–22 carbon atoms). Under normal conditions, it is a clear and transparent liquid with colors ranging from pale yellow, yellow to water-white, and has a greasy or pungent odor. At 20°C, its density is approximately 0.8400–0.8600 g/cm³, and its boiling point range is about 180–370°C. It features low energy consumption and low pollution, and is widely used in vehicles, ships, and construction machinery.
Experimental Objectives
In the fields of chemistry and scientific research, determining the pour point of No. 0 diesel fuel enables the evaluation of the diesel fuel’s fluidity and combustion performance under low-temperature conditions. It also helps monitor the introduction of impurities during the product’s production process to ensure product quality.
The experiment is conducted in accordance with the GB/T 510 standard. Shengtai Instrument’s SH113A-N Petroleum Pour Point Tester complies with this standard, so this instrument is selected for the experiment.
Experimental Instruments
①SH113A-N Petroleum Pour Point Tester (alcohol bath)
②Auxiliary components such as test tubes, sleeves, absolute ethanol, and thermometers.
Experimental Procedures
①Connect the power supply, press the power button, place the coolant in the bath, and add the standard amount of absolute ethanol.
②Take a sample in accordance with the GB/T 4756 standard, shake it well, cover the test tube with a stopper, and fix the thermometer at the center of the test tube.
③ Immerse the test sample vertically in a water bath and heat it to 50℃±1℃. Remove the test tube, wipe the outer wall dry, place it into the sleeve, let it stand vertically until the temperature drops to 35℃±5℃, then immerse it in the cooling bath.
④ After the sample reaches the preset pour point, manually tilt the test tube at a 45° angle, hold it for 1 minute, then remove the sample. Wipe the outer wall of the sleeve with absolute ethanol, place the test tube vertically, and observe whether the liquid level moves.
⑤ If the liquid level moves, re-preheat the sample and conduct the test at a temperature 4℃ lower (or more) than the previous test temperature, repeating until the liquid level no longer moves. If the liquid level does not move, re-preheat the sample and conduct the test at a temperature 4℃ higher than the previous test temperature, repeating until the liquid level moves.
⑥ Identify the temperature range of the pour point, then repeat the measurement at a temperature 2℃ lower than the liquid-moving temperature or 2℃ higher than the non-liquid-moving temperature, and finally determine the pour point.
Experimental Results
Through measurement and analysis, the actual measured pour point of this No. 0 diesel fuel is -4℃, which meets the standard requirements.