Performance Benefits

  • Experience - Therminol 66 is the most popular high temperature liquid phase heat transfer fluid in the world. No heat transfer fluid material in the world has a higher degree of customer satisfaction than Therminol 66.
  • Proven Fluid - In a wide variety of applications and thousands of systems around the world, Therminol 66 delivers excellent performance.
  • True 650° F (345° C) Performance - Therminol 66 sets the performance standard for high temperature liquid phase fluids. Users can expect many years of reliable, trouble-free operation, even when operating continuously at the recommended maximum temperature.
  • Fouling Resistant - Therminol 66 is specifically engineered to resist solids formation and system fouling, providing more reliable operation and potential cost savings.

Typical Properties

AppearanceClear, pale yellow liquid
CompositionModified terphenyl
Maximum bulk temperature345°C (650°F)
Maximum film temperature375°C (705°F)
Normal boiling point359°C (678°F)
Pumpability, at 300 mm2/s (cSt)11°C (52°F)
Pumpability, at 2000 mm2/s (cSt)-3°C (27°F)
Flash point, COC (ASTM D-92)184°C (363°F)
Flash point, PMCC (ASTM D-93)170°C (338°F)
Autoignition temperature (ASTM E-659)374°C (705°F)
Autoignition temperature (DIN 51794)399°C (750°F)
Pour point (ISO 3016)-32°C (-25°F)
Minimum liquid temperatures for fully developed turbulent flow (NRe > 10000)
10 ft/sec, 1 in tube (3.048 m/s, 2.54 cm tube)72°C (162°F)
20 ft/sec, 1 in tube (6.096 m/s, 2.54 cm tube)53°C (128°F)
Minimum liquid temperatures for transitional region flow, (NRe > 2000)
10 ft/sec, 1 in tube (3.048 m/s, 2.54 cm tube)35°C (96°F)
20 ft/sec, 1 in tube (6.096 m/s, 2.54 cm tube)26°C (78°F)
Coefficient of thermal expansion at 200°C0.000819/°C (0.000455/°F)
Kinematic viscosity at 100°C (ASTM D-445)3.80 mm2/s (cSt)
Kinematic viscosity at 40°C (ASTM D-445)29.6 mm2/s (cSt)
Liquid density at 15°C (ASTM D-4052)1012 kg/m3 (8.44 lb/gal)
Liquid density at 25°C (ASTM D-4052)1005 kg/m3 (8.40 lb/gal)
Total acidity (ASTM D-664)<0.2 mg KOH/g
Average molecular weight252
Pseudocritical temperature569°C (1056°F)
Pseudocritical pressure24.3 bar (353 psia)
Pseudocritical density317 kg/m3 (19.8 lb/ft3)
Copper corrosion (ASTM D-130)<<1a
Moisture content, maximum (ASTM E-203)150 ppm
Dielectric constant @ 23°C (ASTM D-924)2.61
Notice: Although the information and recommendations set forth herein are presented in good faith, Eastman Chemical Company and its wholly owned subsidiary Solutia Inc. make no representations or warranties as to the completeness or accuracy thereof. You must make your own determination of their suitability and completeness for your own use, for the protection of the environment, and for the health and safety of your employees and purchasers of your products. Nothing contained herein is to be construed as a recommendation to use any product, process, equipment, or formulation in conflict with any patent, and we make no representations or warranties, express or implied, that the use thereof will not infringe any patent. NO REPRESENTATIONS OR WARRANTIES, EITHER EXPRESS OR IMPLIED, OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR OF ANY OTHER NATURE ARE MADE HEREUNDER WITH RESPECT TO INFORMATION OR THE PRODUCT TO WHICH INFORMATION REFERS AND NOTHING HEREIN WAIVES ANY OF THE SELLER'S CONDITIONS OF SALE.

Safety Data Sheets providing safety precautions that should be observed when handling and storing our products are available online or by request. You should obtain and review available material safety information before handling our products. If any materials mentioned are not our products, appropriate industrial hygiene and other safety precautions recommended by their manufacturers should be observed.