This standard is a guide to the maintenance of silicone liquids in transformers with rated voltages up to 35 kV and is intended to assist the equipment operator in assessing the quality of the liquid during use in the equipment and maintaining it in serviceable condition. Methods for reconditioning silicone transformer liquid are outlined. It deals only with silicone liquids used in equipment where liquid sampling is practicable and which has not previously been filled with any other liquid.