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Specialist Materials for Industry and Science

Oil-filled Transformers

Oil-filled Transformers

When choosing the best product for use in oil-filled transformers, Midel fluids are proven to offer a higher performance alternative to competing products such as mineral oil.

For instance, Midel transformer oils provide 100% fire safety. This is vital for the safety of workers, particularly in small or enclosed spaces such as indoors, underground or offshore. In contrast, mineral oil is highly flammable and so less suited to these applications.

Midel’s improved moisture tolerance has been found to prolong the lifespan of oil filled transformers, particularly when compared with other options including mineral oil and silicone oil.

Discover more about the advantages of our synthetic and natural ester-based transformer fluids:

MIDEL 7131

MIDEL 7131 is our synthetic ester, and is equally suited to sealed and breathing transformers. Its fire safety and environmentally friendly properties make it ideal for offshore and underground applications, particularly because it has a high fire point of >300°C.

It is very low maintenance, and as such has developed a reputation as a ‘fill and forget’ fluid due to the minimal amount of attention it requires to keep performing at a high level. Additionally, it is non-corrosive and is overall a safer and more reliable option than previously widely used mineral oil options.

MIDEL eN

We also manufacture a natural ester. MIDEL eN, that offers another high performance ester for a wide range of transformers. Made using renewable materials, its effect on the environment in the event of a spillage is minimal thanks to its ready biodegradability and non-corrosive properties.

Like MIDEL 7131, it has a 100% fire safety record, while MIDEL eN works best when used in sealed transformers only. For instance, a distribution transformer in a busy area, or inside a building, would be the ideal situation to use MIDEL eN.

If you would like to know more about why Midel fluids the highest performing product for oil-filled transformers, contact our team today.



  • Apiezon
  • Metrosil
  • Midel
  • Wolfmet

Products of M&I Materials Ltd.