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Specialist Materials for Industry and Science



At M&I Materials, we refer to train-mounted transformers as ‘traction transformers’, and there are a number of compelling reasons why MIDEL 7131 has become the fluid of choice for many of these applications.

MIDEL 7131’s attributes make it well suited for use on rolling stock, chiefly its high performance, fire safety and environmental protection.

Its reliability has earned MIDEL 7131 a reputation as the “fill and forget fluid” within the industry, a testament to its ability to continue performing at a high level over a sustained period of time.

MIDEL 7131 is robust and can deliver long term stability at a wide range of operating temperatures, making it perfect for reducing the footprint of traction transformers while maintaining high power output.

Fire Safety

Fire safety is crucial in traction transformers, and MIDEL 7131 provides the reassurance of a high fire point, 100% fire safety record and FM Global® approval. Furthermore, the BS EN 45545 European Standard stipulates that only K-class fluids (i.e. those with a >300°C fire point) should be used on rolling stock.

Environmental Protection

MIDEL 7131 is readily biodegradable, non-toxic and non-water hazardous. This gives it an edge over competitors such as silicone liquid and mineral oil, which have been shown to have a negative effect on the environment.

This is an especially important consideration if your rolling stock needs to travel through environmentally sensitive areas.

Benefits of MIDEL 7131 in Traction Transformers

The advantages of using our synthetic ester fluid are summarised below:

Increased Fire Safety

High Performance

  • Robust and stable, conducive to lower levels of maintenance
  • High temperature performance allowing for compact transformer designs
  • Greater moisture tolerance than mineral oil, silicone liquid and natural ester
  • Excellent reliability, reputation as the ‘fill and forget fluid’

Greater Environmental Protection

  • Readily biodegradable according to OECD 301 and fully biodegradable according to IEC 61039
  • Non-toxic and non-water hazardous

You will also receive excellent customer service from our multilingual commercial team. Our transformer fluid experts will provide first-rate care and continued technical support to all M&I Materials customers. Please contact us for further information.

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Products of M&I Materials Ltd.