How to sample heat transfer fluids safely

Engineer Live News Desk

For the safe handling and sampling of thermal fluids the correct personal protective equipment (PPE) is crucial. Here research scientist Chris Wright from the Global Group of Companies explains.

Managing fluids at high temperatures (upwards of 200 degrees Celsius) presents a safety hazard especially considering that heat transfer fluids (HTFs) need to be routinely sampled by engineers to assess the condition of the fluid but also the system as a whole. The personal protective equipment worn by engineers is thus extremely important. 

PPE is defined as any equipment that offers protection against hazards to protect employee health and safety at work, in the UK this is based on the Work Regulations Act of 1992. This means that engineers sampling a thermal fluid will regularly come into contact with high temperature fluids or the chemical ingredients in a fluid. Engineers must therefore take appropriate precautions when entering potentially hazardous environments such as CSP plants or food processing plants. The safety measures that engineers need to consider are outlined in more detail below. 

Eye protection

Potential eye hazards are the first thing that must be considered. Risks can include the splashing of hot fluids and chemicals, as well as exposure to dust and gas. Best practice dictates that prior to entering a hazardous environment an engineer should put on safety spectacles. 


These spectacles are covered by a facemask to protect the eyes against any adverse vapours or splashes. The mask also protects the wearer’s skin and offers further protection when sampling HTFs. 

Hard hat

On entering any facility, it is compulsory that all relevant staff wear a hard hat to prevent any form of head injury. This includes bumping the head on stationary objects, hair entanglement or impact from falling or flying objects.


An engineer’s uniform should include a disposable filtering face piece or respirator (half or full-face), an air-fed helmet and breathing apparatus. For example, Global Heat Transfer’s engineers wear 3M respirators, which work to filter fumes from the HTF being sampled. 


Engineers should also consider wearing disposable Supertex coveralls and high-visibility clothing. 


Hazards to hands and arms include abrasion, temperature extremes, cuts, contact or contamination with chemicals. Hence, when taking a live HTF sample it is recommended that heat-rated gauntlets are worn. These need to be non-porous and to resist the fluid penetrating the gauntlet. A cotton inner glove is also recommended as this serves as an additional layer against the gauntlet should it come into contact with a live thermal fluid. Furthermore, the cotton glove helps to stop moisture from pooling in the gauntlet.


Much like hands and arms, the feet and legs also need protection from safety risks such as chemical splashes and falling objects. Hence, wearing tight fitting boots is recommended. These need to provide some heat resistance and must have a non-slip sole. Boots should also have a steel toecap to protect the toes and penetration-resistant mid-soles. Open-topped footwear, such as rigger boots, must not be worn when sampling HTFs as a fluid could potentially penetrate this type of boot. 

Ear defenders

In addition to the above, ear defenders should be worn to protect hearing.  

In conclusion

The safe sampling of hot HTFs is a fundamental part of the training procedures that an engineer must undergo prior to being able to sample a working HTF. Engineers need to be regularly trained on sampling procedures and these are needed to enforce the importance of safe handling and sampling of thermal fluids. Indeed, Wagner [1] states that “Relevant regular maintenance services of the system components are necessary and to be carried out by experienced personnel to ensure trouble-free operation of the plant over a longer period.” This needs to be done by experienced engineers, using suitable sampling equipment so that a representative sample can be obtained safely whilst the plant is still in operation [2] and to help extend the lifetime of manufacturing or processing plant [3]. 

Further reading:

[1] Wagner WO. Heat transfer technique with organic media. In: Heat transfer media, second ed. Graefelfing, Germany: Maria-Eich-Straβe; 1997. p. 4–58 [Chapter 2].
[2] Wright CI. Case study in CSP plant performance. Renewable Energy Focus 2015; 16 (2): 22-26.
[3] Wright CI, Picot E. Using routine sampling and chemical analysis of heat transfer fluid, early in a plant build, can help to extend the lifetime of CSP plants: A case study. Renewable Energy Focus 2015: Source:

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