Dielectric Oil Sampling for Dissolved Gas Analysis (DGA)

Standard procedure for collecting transformer dielectric oil samples for dissolved gas analysis, including sampling technique, bottle labeling, sealing, and chain of custody for accredited laboratory evaluation.

Steps

• Verify the work order and sampling requirements
  The supervisor or assigned technician confirms the work order, transformer identification, sample point, required test, and laboratory bottle specification before work begins.
• Inspect the sampling location and confirm safe access
  The technician verifies that the sampling point is accessible and that site controls are in place before approaching the equipment.
• Prepare the sample kit and verify bottle integrity
  The technician lays out the DGA sample kit, checks the bottle or syringe type against the lab requirement, and confirms that all containers are clean and undamaged.
• Purge the sampling point until the oil runs clear
  The technician purges the valve and discards the initial flow until the oil stream is stable and visibly clear, following site disposal controls for purge oil.
• Collect the oil sample using the approved technique
  The technician collects the sample using the lab-specified evacuated bottle or syringe technique, avoiding air entrainment, contact with the container opening, and overfilling.
• Seal and label the sample bottle immediately
  The technician seals the bottle immediately after filling and applies the required label information before leaving the sampling point.
• Complete the chain of custody documentation
  The technician completes the chain of custody form so the sample record matches the bottle label and documents custody transfer from collection to shipment.
• Package and dispatch the sample to the accredited laboratory
  The technician places the sealed sample into approved secondary containment and dispatches it to the accredited laboratory under the required handling conditions.
• Record deviations and escalate non-conformances
  The technician determines whether the sample can proceed or must be recollected and escalated, and records any deviation in the work order.
• Quarantine the affected sample and notify the supervisor
  The technician quarantines the compromised sample, documents the non-conformance, and notifies the supervisor or competent person.
• Close out the sampling record
  The supervisor or assigned reviewer confirms the sampling event is fully documented, traceable, and ready for laboratory follow-up and maintenance review.