What are the requirements for transformer oil sampling bottles?

Transformer oil sampling bottles must be clean, dry, and made of non-reactive materials, such as glass or high-density polyethylene, to prevent contamination. They should be airtight to avoid moisture ingress and should have a capacity of 1 to 2 liters for adequate sample size. Additionally, the bottles must be clearly labeled with the date, location, and type of transformer to ensure traceability and proper analysis.