Effectively using heat transfer fluids

Heat transfer fluids have been used in manufacturing for more than 70 years and have a strong safety record. However, as with every other thing in life, there are risks. Leaking heat transfer fluids present hazards that can affect not only your process but also your health. Being aware of these risks can only help make your experiences while working with heat transfer fluids safer.

With small leaks, the costs associated with fluid replacement are the first concerns that come to mind. But, issues related to fluid odor and employee discomfort also should be addressed. With larger leaks come health and safety issues. Not only is employee discomfort such as breathing difficulty an issue but so is employee exposure to chemicals, thermal burns and insulation fires. By looking at the risks associated with leaking heat transfer fluids, you may be able to keep a small leak from turning catastrophic or at the very least, prevent an injury. Although small fluid leaks may seem to be no more than an inconvenience, all leaks have the potential to become hazardous under the wrong conditions.

Ultraviolet photoionization detectors scan for leaks in heat transfer systems.

Different Fluids Present Different Risks

Undiluted glycols have the potential to ignite. Budd Lee, development engineer at Dow Chemical Co., Midland, MI, noted, however, because glycol heat transfer fluids are water-based and do not have a flashpoint at concentrations below 80% glycol, they are considered less of a fire risk than organic or silicone fluids.

Organic and silicone fluids are designed to be used above their flashpoints. Therefore, if a leak occurs, they pose a greater fire risk than glycols because they are capable of producing flammable vapor concentrations in the area of the leak. Fires involving organic fluids sometimes are caused by catastrophic equipment failure. However, the majority of fires involve improper installation, lack of maintenance on gauges or flow switches, and poor or lacking operating instructions.

Organizations such as the Occupational Safety and Health Association (OSHA), Washington, and National Fire Protection Association (NFPA), Quincy, MA, classify flammable liquids according to their flashpoint. A flashpoint within the operating temperature range of the system obviously is undesirable as any size leak would create an immediate fire hazard.

According to Ander Beain, senior fluids specialist at Solutia, St. Louis, people seem to be more concerned with the toxicity of a fluid presented on a material safety data sheet (MSDS) than the temperature of the fluid they are handling. Heat is more of a safety issue than toxicity in terms of personal safety. It is the temperature of the fluid that causes a thermal burn -- not the fluid's toxicity.

Because heat transfer fluids typically are used at temperatures above 500oF (260oC), thermal burns are a possibility. Fluid running overhead that drips onto an employee can cause an immediate burn. However, it should be noted that thermal burns are not exclusive to heat transfer fluids. Any fluid used at elevated temperatures has the potential to cause a thermal burn if it contacts unprotected skin. The best way to prevent a burn from occurring is to identify small fluid leaks and repair them. Using personal protective equipment such as gloves or long sleeves when repairing leaking equipment or handling fluids also may help prevent a leak from causing a burn. Face shields and respiratory equipment can ease breathing in areas where fumes are present. Prompt and appropriate action is needed if a burn occurs. Jim Oetinger, sales manager at Paratherm Corp., Conshohocken, PA, pointed out that washing vigorously can cause further damage. Instead, Oetinger said the affected body part should be immersed in cold water or gently flushed with cold water to remove any heat and minimize subsequent skin damage.

Employee Training

"It is very important to train employees on the risks associated with any chemicals used at the operating site," said Lee. The federal Right to Know laws require hazardous material training for employees. However, the amount of training provided to employees directly responsible for the heat transfer system is a decision left up to the plant manager. Conrad Gamble, product steward at Solutia, St. Louis, suggests reviewing MSDSs. They may not include all regulations, but will provide some important limits such as American Conference of Governmental Industrial Hygienists (ACGIH) exposure limits.

In some plants, response to a leaking heat transfer fluid is handled based upon the size of the leak. "In any leak situation, employees should be capable of identifying leaks and interrupting the necessary cleanup actions. They may want to rope off certain areas to limit the amount of traffic and reduce the potential for thermal burns. They also should consider fire prevention by shutting off equipment and reporting the leak point for repair," explained Gamble. Oetinger noted that mineral oil leaks are relatively easy to trace and clean up. "Follow the smoke to locate the leak and use an oil absorbent compound to soak up fluid."

Each leak situation is different and can be handled differently. If a small leak occurs, some companies will have plant operations personnel notify maintenance. Others will have outside contractors repair small valve leaks. For larger, catastrophic leaks, some companies may choose to assemble a response team; while others choose to rely on local fire officials. Any of these response methods can work effectively if training is available and current. There is more than one way to safely respond to a leaking fluid, but under no circumstances should a leak ever be ignored.

Although this column focuses on the hazards associated with thermal fluid leaks, it should be noted that thermal fluids are used safely everyday and present little risk to those handling them. Most thermal fluid leaks are small and are more of a housekeeping issue than anything else. Serious leaks, injuries or fires are rare. The best way to keep them from occurring is to clean up small leaks immediately and be aware of the risks associated with the fluids used in your operations.