Paratherm™ HR Synthetic-Aromatic Heat Transfer Fluid

Paratherm™ HR Synthetic-Aromatic Heat Transfer Fluid

High Temperature • High Thermal Stability


Paratherm HR Heat Transfer Fluid is an alkylated-aromatic based heat transfer fluid formulated for closed loop liquid phase heating to 650°F in fired heaters and 675°F in waste heat recovery and full convection heaters.

Applications Include:

  • Gas Processing
  • Chemical Processes
  • Waste Oil Recovery
  • Biodiesel Production
  • Plastic Processing
  • Biomass

Note: If you are experiencing short supply, or long lead times for your currently specified synthetic/aromatic 650°F (terphenyl or alkylated aromatic) heat transfer fluid, call Paratherm for a point-by-point comparison of physical properties. We have product available, and may have just the fluid for your application. +1 (610) 941-4900. Or, use the links on the left side of this page to compare properties with Therminol 66.

High Temperature Stability

Paratherm HR Heat Transfer Fluid offers greater thermal stability than competitive aromatic based fluids that cover similar temperature ranges. Testing (ASTM D6743) shows that, compared to its closest competitor, Paratherm HR Heat Transfer Fluid experiences 1/2 the amount of fluid degradation when maintained at 700°F for 500 hours. Less degradation means less maintenance and longer fluid life.

Low Temperature Startup

Centrifugal pumps are generally specified around the fluid viscosity at the desired operating temperature (usually less than 2 cps). Capacity falls off significantly above 300 cps. So the actual minimum start-up temperature of a fluid is where the viscosity curve crosses the 300 cps line. Paratherm HR Heat Transfer Fluid’s lower cold start-up temperature of 13°F (-11°C) offers a significant advantage over other high temperature fluids.

Comparison of Paratherm HR with Therminol 66*

PropertyParatherm HRTherminol 66
Chemical CompositionAlkylated AromaticModified Terphenyl
Maximum Operating Temperature650°F (343ºC)650°F (343°C)
Maximum Film Temperature700°F (371 C)705°F (374°C)
Minimum Start-up Temp (300 cSt)11.0°F (-12°C)52.0°F (11°C)
Kinematic Viscosity @ 40 C11.0 cSt29.6 cSt
Kinematic Viscosity @ 100 C2.4 cSt3.8 cSt
Density @ 25 C7.98 lb/gal (956 kg/m3)8.39 lb/gal (1005 kg/m3)
**Degree of Decomposition (ASTM D6743)0.150.56

*Therminol 66 is a trademark of Solutia Inc.

**The Degree of Decomposition, measured through ASTM D6743, reflects the overall thermal degradation of a thermally stressed fluid at a specific test temperature. It is determined by adding the total mass percentage of all decomposed products found in a thermally stressed sample. These values were found after both fluids were tested side-by-side at 370ºC (698ºF) for 500 continuous hours. A lower Degree of Decomposition reflects superior relative Thermal Stability of a fluid.

Typical Properties*

Chemical NameAlkylated Aromatic
OdorSlight Odor
Maximum Recommended FilmTemperature700°F / 371°C
Maximum Recommended Oper. Temperature-Fired Heaters650°F / 343°C
Maximum Recommended Oper. Temperature-All Others675°F / 357°C
Minimum OperatingTemperature 20cPs (20 mPa-s)78°F / 26°C
Minimum Start-upTemperature 300cPs (300 mPa-s)11°F / -12°C
Viscosity @ 60°F / 15.5°C cSt (mm2//sec)36
Density @ 60°F / 15.5°Clb/gal (kg/m3)8 (964)
Flash Point Pensky-Martens Closed Cup (D-93)>300°F (149°C)
Autoignition Temperature (Maximum 10 second ignition delay)>780°F/416°C)
Boiling Point (14.7 psia/101 kPa)638°F/337°C
Vapor Pressure @ Maximum operating temp psia (kPa)28.8/195
% Volume expansion over recommended operating temperature per 100°F (°C)5.5 (9.9)
Average Molecular Weight240

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