How should a transformer oil sample be collected and stored?

To collect and store a transformer oil sample, first ensure the sampling equipment is clean and free from contaminants. Use a clean, dry glass or plastic container, and fill it to about 80% capacity to allow for expansion. Seal the container tightly to prevent moisture ingress. Label the sample with relevant details, including date and location. Store the sample in a cool, dark place, away from direct sunlight and extreme temperatures, to maintain its integrity for analysis.