Paratherm™ OR Heat Transfer Fluid

Paratherm™ OR Heat Transfer Fluid

Sludge Resistant, Non-Fouling, Non-Toxic

The Paratherm OR sludge-resistant heat transfer fluid has substantial oxidation resistance and extended service life. This zero-pressure fluid provides precise, uniform temperature control to 500°F in closed-loop thermal oil systems where the heat transfer fluid is more than occasionally exposed to air. The OR fluid is comprised of a unique high-stability base plus high-performance oxidation inhibitor/stabilizer. Performance of the OR fluid is particularly impressive under the same grueling conditions that quickly cause severe oxidation, and sludge formation in conventional heat transfer fluids.

Designed for:

  • Extruders
  • Die temperature control units
  • Easy on quick-connects
  • Safe, easy disposal


Heavy fluid oxidation occurs when supplies of fresh air come into intimate contact with hot heat transfer fluid (during frequent tool changeout, for example). The resulting reaction converts fluid molecules to organic acids. Soon the acids themselves begin to degrade thermally. The fluid becomes thicker, darker and more odorous, and its heat transfer capabilities drop dramatically.


As an oxidized fluid becomes more viscous, it becomes more difficult to pump and more susceptible to overheating. Remaining in contact with the heated surfaces too long, the fluid picks up more heat than its chemical bonds can stand. As they break down, the fluid’s molecules release their carbon forming an acidic, carbonaceous sludge that precipitates out and adheres to the system’s interior surfaces. Much of this sooty, sticky carbon bakes on to the heated surfaces where it was produced. The OR Heat Transfer Fluid contains an additive system that inhibits sludge and carbon formation. Even under prolonged exposure to air, the fluid won’t foul heated surfaces.


Due to its low viscosity, the OR sludge resistant fluid provides unusually high thermal efficiencies — higher than most synthetics. The lower in viscosity (the thinner) a heat transfer fluid is, the less energy is required to pump it through the system. In addition, a smaller pump and motor can be specified, and the lower power consumption will continue to produce savings year after year.

Typical Properties*

Feedstock Hydrotreated Natural hydrocarbon
Color  Transparent, Water-White
Taste & Odor None
Optimum Use Range 175°F to 550°F
(79°C to 288°C)
Maximum Recommended Film Temperature 600°F (316°C)
Flash Point (coc) ASTM D-92 350°F (177°C)
Fire Point (coc) ASTM D-92 395°F (202°C)
Atmospheric Boiling Point, 10% Fraction, ASTM D-1160  631°F (333°C)
Vapor Pressure, psia @ 500°F (260°C) 0.948
Pour Point ASTM D-97 -35°F (-37°C)
Specific Gravity, 60/60 ASTM D-1298 0.8863
Thermal Expansion** 0.0004/°F
Density @75°F (24°C)
ASTM D-4052
7.23 lb/gal
Viscosity @ 40°C  ASTM D-445 40.12 cSt
Average Molecular Weight ASTM D-2502 360
Total Acid Number (TAN)
Heat of Vaporization, Calculated 93 BTU/lb
Electrical Properties
Dielectric Strength kV/cm (disk) ASTM D-877 >35
Dissipation Factor @ 25°C, 60 Hz ASTM D-924 0.0002

Paratherm Heat Transfer Fluids

Critical Temperature, Tc(Calculated)
Units HR™ NF© HE© OR© MR™ LR™ CR™
ºR 1465 1453 1580 1524 1358 1174 1168
ºF 1005 993 1120 1064 899 714 709
K 814 807 878 847 755 652 649
Critical Pressure, Pc(Calculated)
Units HR™ NF© HE© OR© MR™ LR™ CR™
ATM 18.7 11.1 26.5 13.3 12.9 10.7 28.6
PSIA 274 163 389 196 190 157 421
Critical Volume, Vc(Calculated)
Units HR™ NF© HE© OR© MR™ LR™ CR™
cm3/g-mole 816 1579 720 1380 987 1327 493
ft3/lb 0.037 0.072 0.033 0.063 0.045 0.06 0.023
Heat of Vaporization,DH vap
Units HR™ NF© HE© OR© MR™ LR™ CR™
BTU/lb 110 91 77 93 115 113 148
Molecular Weight avg
Units HR™ NF© HE© OR© MR™ LR™ CR™
MW 239 350 445 360 230 160 133
k=Cp/Cv = 1.01
C’ = 316.5
R = 82.06 cm3*atm/mol*K
Fb = 1.0


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