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A heated debate on thermal fluid safety

24 June 2019

Food manufacturers must always prioritise hygiene when reviewing their processes. Clive Jones explains how using heat transfer systems can help improve efficiency and safety. 

Many food and beverage processing applications require consistent indirect heating and cooling processes. Often thermal fluid in heat transfer systems are used to complete these processes, such as pasteurising, heating fryers and ovens or brewing, safely and efficiently. While this method may be safer than more traditional methods, such as steam, a proactive approach should still be taken to ensure the safety of both staff and products. 

Contamination is one of the biggest issues facing food and beverage manufacturers. During production, food can come into direct contact with chemicals, bacteria or another food product, compromising quality. Cross-contamination can lead to costly recalls that also negatively impact brand reputation. Because many heat transfer fluids (HTFs) contain toxic chemicals that cannot be ingested the use of the wrong thermal fluids could dangerously contaminate products. 

Food grade
To prevent the risk of chemical cross-contamination the best solution is to invest in a food-grade thermal fluid – a fluids that is non-toxic, colourless and odourless so that food and beverage products would still meet food safety regulations if there was any incidental contact with the heat transfer fluid. 

Food grade fluids carry a HT-1 certificate, issued by governing bodies such as NSF International and the US Food and Drug Association (FDA). Any manufacturer that wants to sell into the US food market must abide by these standards. The supply of food grade HTFs is also highly regulated in Europe and companies must comply with Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) and Classification, Labelling and Packaging (CLP) regulations, which refer to the classification, labelling and packaging of substances and mixtures. 

Any manufacturer that wants to sell products to supermarkets or fast food chains must be aware of the strict requirements of these establishments. For example, in the UK, suppliers must adhere to the British Retail Consortium (BRC) standards to sell to supermarkets.

Food manufacturers operating heat transfer systems must also consider how workplace safety will impact both its products and its employees. After it is added to the system, a heat transfer fluid will steadily begin to degrade, especially when operating at high temperatures for long periods of time. As the fluid degrades, it can lead to a build up of carbon (heavy ends) in the system, causing inconsistent cooking due to increased insulating effects. and increasing the risk of more dangerous consequences such as leaks and fires. Light ends (fuel volatiles) are also consistently generated and should be ‘vented’ off. Due to this process, flash points and fire points will inevitably fall over time, changing the risk.

The Dangerous Substances and Explosive Atmospheres Regulation (DSEAR) sets out the employer’s minimum obligation to provide a safe working environment and protect employees from fire and explosion risks. By following this, manufacturers can safeguard their facility and the people working in it.

The best way to adhere to regulations and stay on top of maintenance is to work proactively. All employees should be trained on heat transfer regulations and thermal fluid management to ensure any issues are handled efficiently.

Regular visual checks of the system and the facility will allow engineers to address any potential issues before it impacts safety. For example, plant managers can look out for smoking flanges and leaking gaskets, as both are signifiers of a leak.

Plant managers should also ensure that employees can always access safety equipment. Spill kits, which include floor signs, hazard tape, pads, socks and a bin specifically designed for hazardous materials, should be replaced immediately after they have been used to ensure that one is always available in the event of a leak or oil spillage. 

Keeping a comprehensive record of completed maintenance work is a good way to keep track of all the maintenance activities taking place on the heat transfer system. Plant managers can use it to plan future activities to improve efficiency, manage safety or ensure regulatory compliance.  For example, the Dangerous Substances & Explosive Atmospheres Regulations (DSEAR) and ATEX regulations require employers to provide a safe working environment and minimise risks when working with hazardous materials. Keeping clear records of maintenance, educating all staff on heat transfer system safety and providing measures to eliminate risk helps facilities managers to maintain a safe work space. 

On the inside
Maintaining the thermal fluid inside the system is also vital to ensure employee and food safety in the plant. Engineers should regularly sample heat transfer fluid to monitor its condition and proactively look for any changes that imply the fluid needs attention. 

Taking a closed sample when the fluid in the system is circulating and hot is the only way to get an accurate representation of what is happening in the system. One important factor to consider during sampling is the flash points of the fluid — the lowest temperature at which flammable light end vapours will ignite under strict testing conditions and in accordance with ASTM guidelines. A gradual decline in flash point suggests that a system may not be venting effectively, indicating that highly combustible decomposition products are accumulating in the fluid. Regular fluid analysis allows plant managers to monitor fluid degradation and dilute, distil or flush the system before it negatively impacts the quality of food or puts workers at risk. 

Safety audits
Auditing a heat transfer system is a good way to maintain a high level of safety and check that a food manufacturer complies with the required legislation. A safety audit primarily focuses on the condition of the thermal fluid and the main components of the system, including the heater, expansion tank and pipework. The auditor may check the condition of the fluid, how often the company takes samples and whether the company stocks the right level of top-up heat transfer fluid and stores it correctly. 

Auditors should also review the maintenance programme at the facility, including how the plant manager tests and maintains both the fluid and the system. Next, they should check procedures surrounding health and safety — from identifying risks, to managing them and communicating them. Another area that should be looked at is how the company trains its staff in risk management and safety procedures so that everyone knows how to safely work with the system and correctly manage heat transfer fluid.

Plant managers should implement a preventative maintenance programme to clearly demonstrate to an auditor that the facility is safe and adheres to all regulations. It is important to pay attention to food and employee safety when working with potentially hazardous substances such as heat transfer fluid. Regular thermal fluid analysis and maintenance checks can help ensure products continue to be produced safely and efficiently. 

Clive Jones is managing director at Global Heat Transfer.

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