Equivalent to Therminol - 66

Diphyl-THT Heat Transfer Fluid

Product Overview

Diphyl® THT is a high-performance heat resistant synthetic HTF for use in the liquid phase in closed heat transfer systems. It is a clear, colourless to pale yellow liquid. Diphyl® THT Heat Transfer Fluid is odourless and, because of its polyphenyl structure (chemically: partly hydrogenated terphenyls), it has an extremely high thermal stability with a long operating life. Because of its high boiling range, Diphyl® THT Heat Transfer Fluid can be used in pressure-less systems over the entire operating range. The high purity i.e. absence of e.g. chlorine and sulphur contaminants, ensures that there is no corrosion whatsoever of the metals normally employed for heat transfer equipment. The application range is between 0°C and 345°C. The film temperature should not significantly exceed the limit of 370° C, nor exceed it for very long.

Characteristic Data

Parameter Unit Value
Appearance Clear, pale yellow liquid
Odour Inherent odour
Ditolyl ether content weight-% min. 97.5
Pour point °C -54
Boiling range °C 284-294
Flash point °C 135
Autoignition temperature °C 545
Maximum film temperature °C 340
Density (20°C) kg/m³ 1035
Kinematic viscosity (20°C) mm²/s 6.3
Surface tension(20°C) mN/m 37
Thermal conductivity (20°C) W/m.K 0.134
Mean specific heat (20°C) kJ/kg.K 1.58
Net caloric value HU MJ/kg 37.6
Coeff. of therm. expansion (-20 to 300°C) K⁻¹ 10.6 × 10⁻⁴


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To be a reliable supplier by providing innovative products in service solutions.


To be a Leader in Heat Transfer Fluids (HTF) Business and grow our portfolio of speciality chemicals.


To provide customers with top quality products and services in a most responsible manner.

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Diphyl THT Heat Transfer Fluid is a superior heat-resistant synthetic HTF known for its clear, colorless pale yellow liquid form. Its exceptional thermal stability, derived from a polyphenyl structure (partially hydrogenated terphenyls), ensures a prolonged working life. This unique composition makes it an ideal choice for demanding heat transfer applications.

The high boiling temperature of Diphyl THT Heat Transfer Fluid allows for its utilization in non-pressure systems across its working range. This characteristic of Diphyl THT Heat Transfer Fluid enhances its versatility, making it suitable for a wide range of applications without the need for pressurized systems.

Diphyl THT Heat Transfer Fluid has a broad application range, spanning from 0 °C to 345 °C. It finds widespread use in various processes within the chemical and petrochemical industry, including reactors, polymerization processes, distillation columns, and machinery for the production of synthetic resins, plastic raw materials, polyester films, fibers, and more. Additionally, it is employed for energy recovery in waste heat processes in the steel and petrochemical industries.

To maintain optimal performance, it’s crucial to ensure that the film temperature of Diphyl THT Heat Transfer Fluid does not significantly exceed the 370 °C limit and is within an acceptable range. Operators should monitor and control the working conditions to prevent prolonged exposure to high temperatures.

Yes, Diphyl THT Heat Transfer Fluid is commonly used in the production of chemicals like PBT, PET, and purified terephthalic acid (PTA). Its application is prevalent in fiber spinning mills globally, showcasing its effectiveness in critical processes within the chemical and petrochemical industries.


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