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Which dielectric fluids classifications are important to understanding fire safety? — Insulect

Written by Admin | 7 Apr 2026

ANSWER:

IEC 61039 identifies “less flammable fluids” as those with a fire point >300°C. These are designated as K class fluids.

According to IEC 61936 transformers filled with K-class fluids can have reduced fire protection measures.

In addition, certifiers such as FM Global provide a list of approved Less Flammable Transformer Fluids and guides for safe installation.

Using a high fire point fluid significantly reduces the chance of a pool fire.

What does this mean for MIDEL? There has never been an oil fire reported in the past 40 years in transformers using MIDEL ester fluids.

 

Fire Point Comparison: Dielectric Fluids

  • Mineral Oil
  • MIDEL 7131
  • MIDEL eN 1204
  • Mineral Oil
  • MIDEL 7131
  • MIDEL eN 1204
 
 

MORE READING:

The use of ester transformer fluids for increased fire safety and reduced costs.

 
 
 

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Retrofilling transformers with ester fluids