Why are special bottles used for transformer oil sampling?

Special bottles prevent contamination and preserve dissolved gases. For DGA, glass syringes or sealed glass bottles with tight caps minimize air ingress and prevent gas loss. For moisture and dielectric tests, clean dry bottles reduce moisture pickup and particle contamination. Many sampling containers are pre cleaned and sometimes amber colored to reduce light effects on certain additives. Using correct containers ensures lab results reflect true transformer condition rather than sampling errors, which could lead to wrong maintenance decisions.