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  • Excellent thermal stability

  • Improved resistance against oxidation

  • Resists deposit formation

  • Extended oil life

  • Low vapour pressure

  • Does not affect seal materials

  • Non-Toxic

  • High specific heat and thermal conductivity

  • Gives rapid heating in a circulating systems

  • Non-Corrosive

    The system should be thoroughly tested for leaks prior to filling with fluid and commissioning. If the system is suspected of being contaminated with excess levels of debris which would not normally be being picked up by a suitable strainer, or if it has previously been filled with a fluid which is considered to be at the end of its working life, consideration should be given to flushing it with an OIL-UK Flushing Oil or OIL-UK Flushing Additive Concentrate to remove varnishes and oxidised materials. Water must not be used. If flushing is to be applied, the system should thereafter be drained completely and filled with new OIL-UK Therm 32 heat transfer fluid up to a level in the expansion chamber which represents 30-45% of the level expected at operating temperature. All air must be evacuated from the system prior to the temperature reaching operating level. Mineral oil expands when heated so an expansion chamber must be incorporated in the system and a suitable low level alarm switch is strongly recommended to be fitted on the expansion tank. This is the only location where the oil is likely to be in contact with the atmosphere. Precautions must be taken to ensure that exposure to air is minimised, especially if the temperature of the oil in the expansion chamber is likely to exceed 50°C. A floating cover can be used or the oil can be blanketed with inert gas.



OIL UK THERMALFLUID D is a high viscosity heat transfer fluid based on specially selected highly refined mineral oils that provide superior performance in indirect closed heat transfer systems. This product is also non-corrosive and non-toxic, and is suitable for customers requiring a Shell Thermia D type product.

Thermalfluid D has been specially formulated to provide excellent thermal stability and to prevent the formation of deposits and varnishes which can build up over time resulting in reduced system efficiency.

Thermalfluid D exhibits high specific heat and thermal conductivity for rapid heat dissipation, and flows rapidly at low temperatures ensuring excellent start-up circulation. It also exhibits low vapour pressures at elevated temperatures, greatly reducing evaporation, vapour lock and cavitation.


OIL UK THERMALFLUID D is designed for use in closed and sealed secondary heating systems with or without an inert gas blanket where the oil is circulated under atmospheric pressure. Typical applications are Chemical process industries, textile manufacturing and process plants.

OIL UK THERMALFLUID D can be used up to a bulk temperature of 325°C and will stand peak temperatures up to 340°C. The application limits of heat transfer oils depend firstly on circulating speed, and secondly on temperature in closed circuit systems.


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