Health, safety and heat transfer systems

13 February, 2024

Manufacturing facilities in a range of industries rely on heat transfer systems and thermal fluid to indirectly heat products. From foods to pharmaceuticals, various applications require precise temperature control during the manufacturing process to enable desired reactions to occur.

Heat transfer systems containing thermal fluid are safer than the alternative — steam-based systems — mostly because they do not need to be operated at high pressure to maintain a constant temperature. However, companies that use thermal fluid-based systems must proactively maintain them to reduce the risks associated with explosive atmospheres. DSEAR and UKEX (formerly ATEX) provide the overarching regulation that health and safety managers must comply with, what follows are some practices which will help ensure compliance.

Managed risk

Perhaps the most significant aspect of a heat transfer system is the one most easily overlooked. Once inside the system, heat transfer fluid is invisible, so a potentially hazardous issue could easily go unnoticed. For example, fluid degradation — caused over time by oxidation and thermal cracking — can lower a fluid’s flash point, which can increase the risk of fire.

As health and safety managers cannot see the fluid, understanding the outcome of regular sampling by engineers helps them determine the fluid’s condition over time and can inform decisions that can extend fluid lifespan. To provide a representative sample, heat transfer fluids must be sampled while the system is closed, hot and circulating.

The sample can then be sent to a lab for expert analysis. Tests include total acid number (TAN) for carbon levels and a flashpoint test for volatile light ends (VLEs) produced during degradation. If parameters are suboptimal, it’s possible to take remedial action, such as system optimisation, fluid dilution or installation of a light ends removal kit (LERK). By understanding fluid condition, health and safety managers can adapt procedures accordingly to reduce the risk of unplanned downtime caused by using degraded fluid.

Safe site

Another key consideration is the management of the system itself, particularly preventing leaks. A leak might produce a fine mist of fluid, putting employees at risk.

Flange guards can help mitigate the risks associated with mists of fluid in two ways. Firstly, by converting the mist into a visible drip of fluid, they reduce the risk of fire as the drip is less flammable. Secondly, dripping fluid is much more visible than a fine spray, which makes it easier for staff for identify leaks.