Flash Point Management

The flash point of a thermal fluid is the minimum temperature at which the vapours will ignite, or flash off, in the presence of oxygen and an ignition source.

The flash point of a liquid is an indicator of susceptibility to ignition, as it is directly related to the liquid’s ability to generate vapour, that is its volatility. Since it is the vapour of the liquid, not the liquid itself that burns, vapour generation becomes the primary factor in determining the fire hazard. Consequently, the lower the flash point, the higher the risk of fire and explosion.

Managing the flash point of your heat transfer fluid is extremely important from a safety perspective, as prescribed by the DSEAR and ATEX Health and Safety Regulations.

Over time, all heat transfer fluids (HTFs) degrade due to operating at extremely high temperatures. One of the effects of thermal degradation is the formation of light ends, which are lower-boiling, volatile thermal oil components generated at high operating temperatures.

At high operating temperatures, the bonds between hydrocarbon chains start to break, forming light ends in the heat transfer fluid. As the chain length decreases, so does the weight of the molecules, meaning less energy is required to accelerate them to a velocity where they will escape liquid phase.

Being short-chained hydrocarbons, light ends have a lower boiling point and ignition temperature. As a consequence, if they are not managed they will expose the system to fire hazards and lead to operational problems such as cavitation in thermal oil pumps.

Because the system is closed, it is very difficult to know if the flashpoint of your thermal fluid is dropping. If this were the case, the consequences could range from having a less performing thermal fluid, which would negatively impact production, to fire and explosion hazards.

As a consequence, regular thermal fluid testing and analysis is crucial to guarantee the system’s safety and efficiency, as it will indicate if there’s a need for light ends removal. Global Heat Transfer offers a suite of eleven approved thermal fluid tests, including a flash point test, to help you realise in a timely manner if the flashpoint temperature of your thermal fluid is dropping.

The only way to ensure system and workforce safety is through frequent condition monitoring. It is important to apply maintenance strategies and manage the thermal fluid proactively, as suggested by the results of the tests and analysis carried out when monitoring the condition of your thermal oil. Managing and mitigating risks is mandatory, as clearly laid out by the DSEAR and ATEX Health and Safety Regulations.

By using a light ends removal kit as part of a proactive management plan, such as Thermocare, you can extend the life of your thermal fluid and ensure production consistency by avoiding expensive downtime. This can lead to savings up to 75 per cent on maintenance costs, as well as protecting you and your employees from fire and explosion hazards.

Global Heat Transfer provides tailored light ends removal kits (LERKs) designed in accordance to system size, specifications and oil type. To cater for different system layouts, Global Heat Transfer supplies, installs and manages both passive and active LERKS. The difference is that passive LERKs use gravity to return the oil to the circuit, while active ones use a frequency-controlled pump.

Both types can be fitted to new or existing heat transfer systems and can be used on systems of all sizes, since the distiller unit on the kits come in different sizes for systems with a thermal oil volume of anywhere between 2,000 and 100,000 litres. Additionally, the condensators can be air-cooled or water-cooled for systems operating in particularly hot environments

A level control and operator alert system are available for large systems. To better monitor and manage the operations, the electrical control system can be stand-alone or integrated into the Programmable Logic Controller (PLC) of the thermal oil primary system, such as a Siemens S7300 or Allen-Bradley Compact Logix, making it more user-friendly and respondent.

If using an active pump fed unit, you can use LERKs for a fixed duration on a temporary basis. Otherwise, you can use LERKs as a permanent installation to manage light ends on a continuous basis.

The kit works when the hot thermal fluid flows through a distillation vessel and the gaseous light ends are collected in the liquid phase of a condenser. The light ends are drained either automatically or manually from the system. The system is not open to atmosphere as a hot expansion tank would be, which protects the oil against oxidation ageing.