Therminol® 59 Heat Transfer Fluid


Therminol 59 is a synthetic heat transfer fluid with excellent low temperature pumping characteristics and thermal stability.

  • Heating or Cooling Operation—Therminol 59 has surprisingly low viscosity for a high-temperature heat transfer fluid. It is ideally suited for combination heating and cooling applications, delivering great heat transfer rates even at 20°C (70°F). Batch processes will benefit from the excellent cooling performance Therminol 59 delivers.
  • Superb Low viscosityAt exceptionally cold temperatures makes this an ideal fluid for colder climates. In fact, Therminol 59 was originally developed for use on the North Slope in Alaska, a supreme test of low-temperature pumpability.
  • Long Life Means Low Cost—High reliability, trouble-free operation, even when operating continuously at the recommended upper temperature limit of 315°C (600°F). Long life means fewer fluid change-outs, and that means low operating cost.

Typical Properties

PropertyTest MethodTypical Value, Units
AppearanceClear yellow to dark amber liquid
Composition Alkyl substituted aromatic
Maximum bulk temperature315 °C (600 °F)
Maximum Film Temperature345 °C (650 °F)
Normal Boiling Point289 °C (553 °F)
@ 300 mm2/s (cSt)
@ 2000 mm2/s (cSt)

-37 °C (-35 °F)
-49 °C (-56 °F)
Autoignition TemperatureASTM E659
DIN 51794
372 °C (702 °F)
404 ºC (760 ºF)
Flash Point


146 °C (295 °F)
132 ºC (270 ºF)
Pour PointISO 3016
-68 °C (-90 °F)
-61 ºC (-78 ºF)
Minimum liquid temperatures for fully developed turbulent flow (NRe > 10000)
10 ft/s, 1-in. tube (3.048 m/s, 2.54-cm tube)
20 ft/s, 1-in. tube (6.096 m/s, 2.54-cm tube)

17 °C (63 °F)
0 °C (32 °F)
Minimum liquid temperatures for transitional region flow, (NRe > 2000)
10 ft/s, 1-in. tube (3.048 m/s, 2.54-cm tube)
 20 ft/s, 1-in. tube (6.096 m/s, 2.54-cm tube)

-16 °C (4 °F)
-24 °C (12 °F)
Coefficient of thermal expansion @ 200°C0.000946 /°C (0.000525 /°F)
Heat of Vaporizationa227 kJ/kg (97.5 Btu/lb)
Viscosity, Kinematic
@ 100ºC
@ 40ºC

ASTM D 445
ASTM D 445

1.44 cSt, mm2/s
4.00 cSt, mm2/s
Liquid Density
@ 15ºC
@ 25ºC

ASTM D 4052
ASTM D 4052

978 kg/m3 (8.16 lb/gal)
971 kg/m3 (8.10 lb/gal)
AcidityASTM D 664<0.2 mg KOH/g
Pseudocritical temperature514 °C (957 °F)
Pseudocritical pressure22.3 bar (323 psia)
Pseudocritical density287 kg/m3 (17.9 lb/ft3)
Molecular Weight (Average)207
Moisture Content, maximumASTM E-203200 ppm
Dielectric Constant @ 23°CASTM D-9242.52
Copper CorrosionASTM D 130<<1a
Properties reported here are typical of average lots.

Key Attributes

  • Heating or Cooling Operation
  • Long Life Means Low Cost
  • Superb Low Temperature Pumpability


  • htf – production of biodiesel
  • Biomass – orc
  • Desalination
  • Gas to liquid (gtl)
  • Natural gas purification
  • Oil or gas processing
  • Polymer & plastic
  • Specialty chemicals
  • Waste heat recover + orc

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