Test Method for Water Content in Petroleum Products

Test Method for Water Content in Petroleum Products

Petroleum products refer to the general term for various commodities that meet specific quality standards, produced from petroleum or its components through refining processes such as distillation, cracking, and purification. These products are widely used in energy, chemical, transportation and other fields, including gasoline, diesel, kerosene, lubricating oil, liquefied petroleum gas, asphalt, etc.

Experimental Purpose

The presence of water causes various harms to the performance and application of petroleum products, so it is crucial to accurately determine its water content through experiments. The main purposes are summarized as follows:

1.Ensure product quality and performanceWater accelerates oil oxidation, promotes gum formation, reduces calorific value and affects combustion efficiency. In lubricating oils, water damages the lubricating film and increases mechanical wear. Testing allows timely control of moisture to ensure stability during storage and use.

2.Prevent equipment damage and operational accidentsWater in fuel oils tends to freeze at low temperatures, blocking fuel lines and filters. In aviation fuels, it may cause serious safety incidents such as fuel supply interruption. Excessive water in insulating oils (e.g., transformer oil) significantly reduces dielectric strength, endangering the safe operation of power systems.

3.Improve production and transportation efficiencyWater in crude oil or petroleum products increases energy consumption during transportation and refining, as water vaporization absorbs large amounts of heat, leading to higher system pressure and energy consumption. Water content testing helps optimize dehydration processes and reduce production costs.

Experimental Sample and Instruments

Experimental Sample: Petroleum product

Experimental Instrument: Model SD260B Dual-unit Petroleum Water Tester, in compliance with ASTM D95

Experimental Procedure

1.Preparation of instruments and reagentsPrepare distillation flask, condenser, water receiver (2 mL / 10 mL), heating mantle, and boiling chips.Use anhydrous toluene (or xylene). All glassware shall be dry and clean.

2.Sample weighingShake the sample thoroughly to ensure uniformity and representativeness.Weigh 50–100 g of sample (accurate to 0.1 g) and transfer it into the distillation flask.Add 100 mL of toluene and an appropriate amount of boiling chips, then mix gently.

3.Assembly of apparatusConnect the distillation unit in sequence: flask → water receiver → condenser.Pass cooling water through the condenser, and lightly plug the top opening with absorbent cotton to prevent moisture ingress.

4.Heating and distillationHeat the sample gradually, controlling the reflux rate at 2 to 5 drops per second.Continue distillation until no further increase in water volume is observed in the receiver within 30 minutes.Stop heating and allow the apparatus to cool to room temperature.

5.Reading and cleaningRead the volume of water V (mL) in the receiver, estimating to the smallest division.Use a copper wire to push any water droplets adhering to the tube wall into the water layer for accurate reading.Disassemble, clean and dry the instrument for future use.

Experimental Result

Tested in accordance with ASTM D95, the water content of the sample is 0.15%.