How is transformer oil sampling performed to avoid contamination?

Sampling is performed by cleaning the sampling point, flushing stagnant oil, and collecting in clean, dry, approved containers. For DGA, gas tight bottles are filled with minimal headspace and sealed immediately. Operators avoid splashing, shaking, or rapid flow that introduces bubbles. Gloves and clean tools prevent external contamination. Samples are labeled and stored properly, then transported quickly to the lab. Consistency in method and timing improves trend quality and reduces false alarms from poor sampling technique.