Paratherm™ GLT Heat Transfer Fluid

Paratherm™ GLT Heat Transfer Fluid

Thermally Stable • Low-Temperature Start-Up

The Paratherm™ GLT heat transfer fluid is an alkylated aromatic based heat transfer fluid formulated for closed-loop liquid-phase heating systems to 550°F.

Applications Include…

Thermally Stable

Paratherm™ GLT Heat Transfer Fluid exhibited almost 40% less degradation when exposed to 600°F (316°C) for 500 hours than a widely used competitive fluid. Although very few heaters expose the fluid to the maximum film temperature for extended periods, this level of stability helps insure that your system operates trouble free during operating upsets.

Low Temperature Capability

Minimum startup temperature is a realistic measure of a fluid’s low temperature capability since 300 cps is the maximum viscosity that a centrifugal pump can handle. Paratherm™ GLT Heat Transfer Fluid has a lower minimum start-up temperature 18°F (-6°C) than any mineral-oil based fluids that cover a similar temperature range.

Comparison of Paratherm™ GLT with Therminol 55*

Performance Data: Paratherm™ GLT vs. Therminol 55

ASTM D6743 – Thermal Stability of Organic Heat Transfer Fluids

Fluid samples held at 316°C (600°F) for 500 hours to assess stability to continuous thermal stress
The total degradation is determined by the total mass percentage of high boilers, low boilers and other decomposition products found in the thermally stressed sample. This value reflects the overall thermal degradation of the stressed fluid as a direct result of thermal stress.

A lower degree of decomposition is directly proportional to the overall thermal stability of the heat transfer fluid relative to other samples tested under the same conditions


Side-by-side testing of Paratherm™ GLT vs. Therminol 55 provides evidence that the GLT fluid has significant thermal stability advantages under demanding operating conditions. The primary contributing factor to the total degradation of alkylated aromatics is the high boilers. High boiling degradation by-products are polyaromatics that lead to sludges, tars and varnishes, and a complete change in physical properties. High decomposition rates have a significant impact on the designed performance of the fluid and will increase the potential for lost production, shortened equipment life and frequent clean-out procedures due to fouling.

Results Matter

Paratherm™ GLT exhibits superior stability with nearly half the total degradation experienced by Therminol 55 under demanding conditions.

*Therminol 55 is a trademark of Eastman Chemical Company.

Typical Properties*

Chemical Name Alkylated Aromatic
Appearance  Clear Amber Colored
Odor Sweet
Maximum Recommended Film Temperature 600°F / 316°C
Maximum Recommended Operating Temperature 550°F / 288°C
Minimum Operating Temperature 20cPs (20 mPa-s) 95°F / 35°C
Minimum Start-Up Temperature 300cPs (300 mPa-s) 17°F / -8°C
Viscosity @ 60°F / 15.5°C cSt (mm2//sec) 63
Density @ 60°F / 15.5°C lb/gal (kg/m3) 7.4 (880)
Flash Point Pensky-Martens Closed Cup (D93) >340°F (171°C)
Boiling Point (14.7 psia/101 kPa) >700°F (371°C)
Vapor Pressure @ maximum Operating Temp. psia (kPa) 3.5 (25)
% Volume expansion over recommended operation temperature per 100°F (°C) 6.0 (10.8)
Average Molecular Weight 330


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