Determination of Demulsibility of Petroleum Products (Water Separability)

Determination of Demulsibility of Petroleum Products (Water Separability)

Overview

During the service of petroleum products and synthetic fluids, they inevitably come into contact and mix with water, forming stable emulsions. This reduces the lubricity, cooling performance and insulating properties of the oils, accelerates their oxidative deterioration, and affects the normal operation of equipment. Demulsibility (water separability) is a key indicator to measure the ability of oils to separate rapidly from water, which is directly related to the service life and equipment safety of industrial oils such as turbine oils, hydraulic oils and gear oils.

Experimental Purpose

In accordance with GB/T 7305-2003 Method for Determination of Water Separability of Petroleum Oils and Synthetic Fluids and GB/T 7605-2008 Method for Determination of Demulsibility of In-Service Turbine Oils, this experiment determines the demulsification time and layering state of petroleum products, evaluates the demulsibility of oils, and provides reliable data support for oil quality judgment and equipment oil selection.

Experimental Samples and Instruments

- Experimental sample: Petroleum product to be tested (turbine oil, hydraulic oil, etc.)

- Experimental instruments: SH122 Petroleum Demulsibility Tester, glass graduated cylinders

Operating Procedures

1. Add water to the specified liquid level in the constant-temperature glass bath of the tester, connect the power supply with reliable grounding, and check the instrument status.

2. Clean the glass graduated cylinders until no water droplets adhere to the inner wall. Measure 40 mL of sample and 40 mL of distilled water separately, and add them into the cylinder to the 80 mL mark.

3. Place the cylinder into the constant-temperature bath of the tester and let it stand for about 10 minutes (maximum 30 minutes) to equalize the temperature of the oil-water mixture with the bath temperature.

4. Power on the tester to enter the main interface. Set the test temperature (commonly 54℃ or 82℃) and stirring time (standard 5 minutes) in the setting interface, and fine-tune the temperature as required.

5. Enter the test interface. After the tester automatically stabilizes at the set temperature, press the Start button of the corresponding channel. The head will automatically descend for stirring, rise automatically after completion, and start timing.

6. Observe the layering state. Press End and record the separation time when the volume of the emulsified layer is no more than 3 mL. If complete separation is not achieved after 30 minutes, record the volumes of the oil layer, water layer and emulsified layer.

7. After the experiment, reset the head, clean the graduated cylinders and the tester, and drain the water only after the bath liquid cools down.

Data Analysis and Result Evaluation

Under the specified temperature, the sample forms an emulsion with water after stirring. Rapid layering with an emulsified layer ≤ 3 mL indicates excellent demulsibility of the oil. If a distinct emulsified layer remains after 30 minutes, the water separability is poor and fails to meet the application standards. This method features stable test data and good repeatability, and can accurately reflect the demulsibility of petroleum products.