What kind of oil is inside a submersible pump?
2 Answers
The oil inside a submersible pump is transformer oil. Transformer oil primarily serves the functions of insulation, heat dissipation, and arc suppression. Functions of transformer oil: Insulation: Transformer oil has a much higher insulation strength than air. Heat dissipation: Transformer oil has a high specific heat capacity and is commonly used as a coolant. Arc suppression: In oil circuit breakers and on-load tap changers of transformers, arc is generated when contacts are switched. Composition of transformer oil: Transformer oil is a fractional distillation product of petroleum. Its main components are compounds such as alkanes, cycloalkane saturated hydrocarbons, and aromatic unsaturated hydrocarbons. Commonly known as insulating oil, it is a light yellow transparent liquid with a relative density of 0.895 and a freezing point of <-45 degrees Celsius.
The oil filled in submersible pumps is actually an insulating oil, with transformer oil or specialized pump oil being the most common. I've repaired this type of pump many times, and the oil mainly serves to seal and cool, ensuring the components run smoothly without water ingress. If you casually pour motor oil into it, it's a disaster—motor oil corrodes rubber seals, leading to leaks in no time. Many auto repair shops use No. 25 transformer oil, which is both pressure-resistant and cheap. Extra attention is needed in hot weather, as high oil temperatures can easily cause carbonization, and a buzzing noise is a warning sign. Remember to check the oil level every two years; if it's cloudy or black, it's time for a change.
