Séparateur flexible d'huile STPSéparateur flexible d'huile STP

STP flexible separators

The STP flexible separators for transformers, also known as “bladders”, “aircell” or “compensation balloons”, protect the dielectric oil in the power transformers. By compensating for their variation in volume, the STP handles the separation between the air and the oil inside the hydraulic conservator. This way the dielectric oil is protected from outside contamination.

Our compensation bladders are custom made (material, shape, dimensions, flange and mounting feed). Their tightness to gas, oil, and water as well as their high mechanical resistance make Pronal STP Bladders a high performing system to protect your electric power transformer.



  • No maintenance
  • Quick and easy installation
  • Dimensions and accessories custom made


  • Oil protection
  • 100% gas/oil/vapour-proof
  • Delivered with conformity certificates


  • Vulcanized flange
  • Resistant to temperature variations
  • Compatible with a wide range of oils

Detailed information

  • Material: high quality coated fabric
  • Manufacturing technique: hot vulcanization in a vacuum autoclave
  • Dimensions: custom made > contact us
  • Inflation: atmospheric pressure
  • Temperature resistance: -50°C to +120°C
  • Material options: compatible with new generation oils
  • Accessories:
    • Flange
    • Fixation lugs

You can not find your dimensions

Our design department employs the best project leaders and designers and will be pleased to develop and create a tailor-made product specially for your unique project.


Composition / Advice

Care during use
Avoid any contact with surfaces that are excessively abrasive or have cutting edges. Never walk on the product.
Maintenance advice
There are no fixed maintenance intervals. To check after prolonged storage or after use.
Storage advice
Store away from light, damp and temperature variations, in its original case.
Inflation advice
Tested at 0.105bar max. for 12 hours / in use at atmospheric pressure.

Standards / regulations

1 year against all manufacturing defects
ISO 9001, ISO 140001, ISO 45001
Product test
Product delivered with its conformity report.


Fact Sheets / Business Guides
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