Hot stuff: Keep industrial systems running smoothly
In industrial systems where temperature control is key, heat transfer oil is the quiet workhorse keeping things running smoothly. From heaters to high-performance machinery, thermal fluids carry heat where it’s needed – and when chosen wisely, they protect your equipment, improve efficiency, and extend service life.
What is Heat Transfer Oil?
Heat Transfer Fluid, also known as Thermal Fluid or Heat Transfer Oil, is a liquid designed to move heat (thermal energy) from one section of a system to another. These fluids play a vital role in many industrial and commercial applications requiring controlled heating or cooling — often in closed circuits and continuous cycles.
A common everyday example is the cooling system in a car engine. Here, the coolant absorbs excess heat from the engine and carries it to the radiator, where it is dissipated. This same principle applies on a much larger and more complex scale in industrial settings.
Why Water Isn’t Always the Answer
Water is the most commonly used heat transfer fluid due to its affordability, high heat capacity, and effective heat-carrying properties. However, its temperature range is limited — freezing at 0°C and boiling at higher temperatures depending on system pressure. When systems operate at elevated temperatures, water quickly reaches its limitations.
This is where mineral-based heat transfer oils come into play.
Oil: A Smarter Solution for High Heat
For higher temperature applications, mineral oil is a reliable alternative. A familiar example is the domestic oil heater — a portable heater with metal columns filled with heat transfer oil. A heating element warms the oil, which circulates by convection. The heat then transfers through the metal surface into the surrounding air, warming the room. The large surface area of the columns helps ensure even and safe heat distribution.
In industrial settings, thermal fluid systems are more advanced. These systems use pumps to circulate the oil (forced circulation), which is far more efficient than natural convection. Most industrial systems are closed-loop designs that prevent the oil from coming into contact with oxygen, thus limiting oxidation and extending oil life.
These closed-loop systems can distribute heat from a single source (such as a gas, oil, electric, or biomass-fired heater) to various stations, each with different temperature needs. Because these systems can contain hundreds of litres of thermal fluid, the oil must be high-performing and long-lasting.
What Makes a Good Heat Transfer Oil?
Choosing the right heat transfer oil is essential for maintaining system efficiency and reliability. Here are the key properties to look for:
- Low viscosity: Promotes smooth circulation and effective heat transfer.
- Good heat stability: Prevents thermal breakdown and sludge formation.
- High boiling point: Reduces the risk of fluid vaporisation at high temperatures.
- Large thermal capacity: Allows small volumes to move significant amounts of heat.
- High flash point: Improves safety by reducing fire hazards in open systems.
- Good solvency: Minimises deposit build-up and keeps heat exchange surfaces clean.
- Low volatility: Prevents pressure build-up in closed-loop systems.
- Noncorrosive formulation: Protects internal metal surfaces from rust and corrosion.
- High thermal conductivity: Ensures efficient heat transfer from the oil to system components.
Formulation and Maintenance Matters
Quality heat transfer oils are formulated using highly refined mineral base stocks combined with performance-enhancing additives. These formulations are designed to meet the demanding conditions found in industrial applications. A good rule of thumb is to always operate within recommended temperature guidelines for your specific system to maximise oil life and system performance.
A few simple maintenance checks and the right choice of oil can go a long way in ensuring your thermal fluid system runs trouble-free for years.