How to take electrical oils via glass bottle

Glass sample containers are used instead of plastic to reduce to prevent loss of gases dissolved in the oil. Usually 500ml is of sufficient volume for most suites.


The oil under examination should be used to flush the sample valve by running one to two litres of oil to waste.


It is helpful to use rubber tubing fitted to the transformer drain tap to assist obtaining a representative sample and avoid introducing air into the oil. Ideally this tubing should be a short as possible and be made of Silicone rubber, which will not be affected by the oil or easily weather or perish in time. However this option is not always possible, so normal rubber tubing or even a copper metal pipe will prove suitable.


After flushing the valve the bottle should also be flushed with oil then filled to leave a gap of 1 to 2 mm from the top to allow for expansion, but reduce loss of gases to the headspace. Replace the top and return the bottle to the shipping container.


The form accompanying this sample bottle should be filled-in to ensure all the information required by the lab, is provided. The sample should then be despatched to the lab asap.  


Note that transformer oils may contain Poly-Chlorinated Biphenyl compounds (PCB’s), which maybe harmful to the person and the environment, so this waste oil should be disposed of in a responsible manner, i.e. kept safely until the oil has been tested for PCB’s. If the oil is found to contain PCB’s the oil should be disposed of separately to other waste oils, inline with current legislation.


Most sample bottles will withstand fluids at temperatures up to 85 Centigrade. However we strongly recommend temperatures do not exceed 80C to reduce the risk of burns to the skin with hot fluids. Always use protective gloves and face mask. It is best to confirm with your bottle provider the best safety practices before using.