Heat transfer fluids are substances used to transfer heat from one location to another. They come in various types, each offering unique properties suitable for indirect heating or cooling of equipment like process reactors, molds, or extruders. They are also utilized in portable oil heaters and temperature control units. These fluids are sometimes referred to as thermal oil, thermal fluids, hot oil, or heat transfer oil.

No, not all fluids are compatible. While most petroleum-based fluids are generally compatible, some glycol-based, aromatic chemical, or synthetic fluids may not be. It's important to consult your supplier's technical service department for recommendations. If you're switching from an incompatible fluid, ask your supplier for a compatible flushing fluid to avoid any issues.

It's normal for heat transfer fluids to change color after some use, especially in older equipment. If you're confident the system is relatively clean, the color change is likely due to the fluid's normal aging process and doesn't necessarily mean it needs to be changed. However, to be certain, the fluid should be analyzed.

The service life of heat transfer fluids varies based on their quality and the equipment they're used in. In extreme cases, a fluid might need to be changed after a few months; in other situations, it can last over ten years. The only way to accurately determine if your fluid is still effective is through specific laboratory analysis, a service your supplier should provide.

The effectiveness of a heat transfer fluid depends on the system it's used in. Some fluids perform better in closed systems, while others excel in open systems such as those used in plastic processing. While the base stock of the fluid is important, the additives—like oxidation inhibitors and rust and corrosion preventatives—play a crucial role in extending the fluid's life. Using a fluid with the appropriate additives can keep your system running longer and cleaner between oil changes, especially if the system is open to the atmosphere.