Which method is used for taking oil samples for gas-in-oil testing?

The method used for taking oil samples for gas-in-oil testing is ASTM D3613. This standard provides detailed procedures for collecting and handling oil samples to ensure accurate analysis of the gas content in the oil. Proper sampling techniques are crucial because they help minimize the introduction of contamination or loss of gas, which could potentially skew the results of the testing.

ASTM D3613 specifically addresses the sampling conditions and preservation techniques that are pivotal when dealing with gas content. This standard ensures that the physical and chemical characteristics of the oil are retained from the time the sample is taken until it is analyzed. In gas-in-oil testing, it is important to capture the actual state of the oil, along with any dissolved gases, for a reliable evaluation of the system's condition.

The other methods listed deal with different aspects of oil testing. For example, ASTM D5001 focuses on specific gravity measurements, ASTM D877 is concerned with the breakdown voltage of insulating liquids, and ASTM D1920 addresses the determination of the viscosity of oils. While these are important tests in the field of substation maintenance, they do not apply to the specific requirements for gas-in-oil testing, making ASTM D3613 the correct standard for oil sampling in that context.