Thermaflo® Flushing Fluid
THERMAFLO® Flushing Fluid (TFF) is a low cost, aromatic oil, which functions as an excellent tar solvent. It is comparable in solvency to a flammable solvent such as toluene, without the safety and toxicity issues. TFF also breaks loose baked on carbon deposits, by ‘wetting’ the metal better and getting under the hard solids for removal from the hot oil system.
Using TFF is very simple: Drain the system (preferably while still warm), and fill with enough TFF to circulate to all parts of the system (usually 70 to 100% of fill volume), heat system to just below the flash point of 140°C (280°F), and circulate for 8-12 hours. The fluid should turn black, and get more viscous. Any TFF remaining in the system after draining is compatible with heat transfer fluids, and should vent from the system expansion tank when coming up to normal operating temperature.