
To protect performance in onsite applications ranging from pharmaceutical manufacturing to solar energy collection selecting the correct heat transfer fluid (HTF) is critical, however it’s merely the first step.
Making certain that you deploy the optimal fluid for the role required needs annual fluid sampling and analysis, but also understanding when the HTF needs replacing.
High-quality HTFs from leading brands like Paratherm are specially formulated to supply years of uninterrupted service. However, fluid lifespan is impacted by many factors including the operating temperatures present, time and design; these factors can vary greatly between systems.
When necessary, changing HTFs is vital to maintain system performance and dependability. Over time, fluids degrade because of factors like oxidation, temperature fluctuations, contamination and organic growth. This degradation has many unwanted outcomes including decreased thermal efficiency, system blockages and potential harm to essential components.
Neglecting to replace the HTF on schedule can cause a buildup of particulates, sludge, and other deposits that block internal passages, putting strain on the compressor or pump and reduce heat transfer. Over time, such a maintenance failure can drastically cut the lifespan of your equipment, resulting in unexpected downtime for expensive repair work.
When to change Heat Transfer Fluid
The frequency of HTF changes can vary widely depending on the fluid type used and process conditions present. However, there are some key signs that can help users determine the best time to replace fluids.
HTF appearance
Carrying out a visual inspection of the HTF in use is among the most straightforward ways to work out if a fluid requires replacement. As a rule, fresh HTF is clean and completely free of particulates. However, as it starts to degrade, it can become discoloured and form suspended particles. Finding sediment or sludge in the system is another warning sign that the HTF is no longer performing its role effectively.
Elevated levels of high-molecular weight degradation matter nearing or, in worst case scenarios, exceeding their solubility limit in the HTF and contamination of the HTF with foreign compounds, are both indicators to look for.
HTF odour
Fluid smell can also indicate that HTFs have degraded. Many fluids, like those with an oil or glycol base, can give off a noticeable odour when they start to break down. Detecting an unusual smell is a strong sign that the HTF has overheated or oxidized and should be immediately replaced. The development of acids caused by oxidative degradation often leads to corroded internal components, resulting in further system issues when not dealt with promptly.
Operating temperatures
When the heat transfer system and HTF can’t maintain the right operating temperature for the process, it is an indication that the fluid has degraded and requires replacing. Onsite engineers may notice this issue if they find they are turning up the system’s temperature frequently, but flow rates remain reduced.
The temperatures at which systems operate have a substantial impact on the longevity HTFs. Processes with temperatures near room temperature usually have slower fluid degradation, resulting in less frequent fluid changes. However, under more extreme temperatures, like the high end of the HTFs rated range, rapid breakdown can occur. Operating higher than the HTFs recommended temperature can permanently alter its chemical formulation and performance levels.
Increased energy costs
When an HTF requires replacing, increased cost onsite can be an indicator. Aged fluid can result in increased energy costs at the heater but also see a rise in pumping energy costs. A loss of efficiency in heat transfer at process heat users can potentially impact throughput rates and an elevation in HTF viscosity results in decreased pumpability.
Why fluid sampling and analysis is key
Users should collect a representative sample of the HTF in use to determine its current condition before replacing. HTF sample data can detail high total acid number/ acidity and data on carbon residue. Results can show likely levels present of system fouling but also particulate quantity and viscosity results. If suspended, matter in an HTF reaches more than 5% of the system’s total volume, it is not suitable for use.
Advantages of Paratherm HTFs as replacement fluids
Paratherm supplies a wide range of specialised HTFs designed for different applications and operating conditions making it easier to ensure your fluid choice has optimum active service life. Offering best-in-class heat transfer efficiency and stability fluids are specially formulated to resist thermal decomposition at higher temperatures. For extreme applications Paratherm also provides sludge resistant HTF that inhibit oxidation, resist sludge and fouling and offer extended fluid lifespan in environments prone to oxidation.