Heat transfer fluid is the thermal oil circulated through a closed-loop heating system — a fired heater, calorifier or electric thermal fluid unit feeding jacketed vessels, presses, dryers, calenders or reactors — carrying heat at atmospheric pressure instead of the high pressures steam would need for the same temperature. Harlow Lubricants Supplies is an authorised distributor for Shell, Mobil, Fuchs and TotalEnergies, with 35 years in lubricant supply, and we stock mineral and food-grade thermal fluids in 20 L pails, 205/208/209 L drums, 1,000 L IBCs and bulk for UK delivery and export to Nigeria, Ghana, Kenya and South Africa.
Need a quote or a data sheet? Tell us the system, the bulk operating temperature and the volume, and we reply with stock and lead time.
Every drum is genuine, manufacturer-sealed stock supplied with its technical and safety data sheets. Quotes go out the same working day with stock position and lead time against them.
What is heat transfer fluid and how does it differ from other oils?
A thermal fluid is engineered for one job: to absorb heat at the heater, carry it to the process and give it up, thousands of times over, without breaking down. That means high thermal stability, good flow at start-up temperature, and resistance to the cracking and polymerisation that produce light ends and carbon.
It is not a lubricant and should never be substituted with hydraulic or gear oil. The additive packages that make a hydraulic oil good at protecting a pump are exactly what degrade and foul a thermal loop.
Which heat transfer fluid grade do I need?
Grade selection is driven by your maximum bulk temperature and the heater’s maximum film temperature, both of which the system manufacturer specifies. Running a fluid beyond its rated film temperature is the single most common cause of premature degradation — the fluid does not fail gradually, it cokes on the heater tube.
The lighter grades flow better on cold start and suit systems that cycle; heavier grades suit steady high-temperature duty. If the system is being recommissioned or you have inherited it without documentation, tell us the heater make and model and we will work from that rather than guessing.
Which thermal fluids do you stock?
- Shell Heat Transfer S2 — 20 L, 209 L drum, 1,000 L and bulk delivery.
- Mobil Mobiltherm 605 — 20 L and 208 L drum.
- TotalEnergies Seriola 22 and Seriola 2100 — 1,000 L and bulk delivery.
- Aztec Heat Transfer Oil 22, 32, 46, M46 and 68 — 20 L, 205 L drum and 1,000 L IBC across the range.
- Fuchs 610T Heat Transfer Oil — 20 L.
- Fuchs Cassida FM Heat Transfer Fluid 32 — food-grade, for systems where incidental food contact is possible.
Do you supply food-grade heat transfer fluid?
Yes. Fuchs Cassida FM Heat Transfer Fluid 32 is formulated for food and beverage processing where a thermal loop runs near product. If your site is audited to a food safety standard, specify the food-grade fluid even where contact seems unlikely — retrofitting after an audit finding is considerably more expensive than specifying it correctly up front.
How often should thermal fluid be tested or changed?
Thermal fluid should be sampled and analysed on a regular schedule rather than changed on a fixed interval. Analysis looks at viscosity shift, acidity, flash point and the build-up of carbon and light ends, and it tells you whether the fluid is degrading and why — usually overheating, oxidation from air ingress, or contamination.
Catching degradation early matters because a degraded fluid attacks the system as well as itself: light ends lower the flash point and create a safety issue, while carbon fouls the heater and reduces efficiency long before anything stops working.
What pack sizes can I buy?
20 L pails for top-up, 205/208/209 L drums, 1,000 L IBCs and bulk road tanker delivery for a full system fill or a change-out. A first fill is usually bulk or IBC; routine top-up is usually drums. Tell us the system volume and we will quote the format that makes sense.
Prices are quoted per enquiry, the same working day; orders over €10,000 receive a 10% discount and we price-match like-for-like genuine product. UK deliveries normally arrive within 2–5 business days, and we export with the data sheet and safety data sheet in the shipment.
Related ranges: hydraulic oil, industrial gear oil and transformer oil.
