When considering a heat transfer fluid, you need to evaluate the heat transfer fluid's overall physical properties relative to performance, safety issues and operational issues. Any one of these could be the driving force to choose one fluid over another, but most of the time the physical properties drive most customers' decisions.

Physical properties dictate the design of the system. Design engineers look for such properties as a high specific heat, high thermal conductivity, high density, low viscosity and low vapor pressure. These factors allow the engineer to determine how many coils and the length of pipe they need to run to meet the application requirements, according to Jed Seybold, sales manager at MultiTherm in Devault, Pa.

Safety issues are important in creating a safe environment for your employees as well addressing any insurance constraints put on your facility by your insurance policy.

Operational Issues affect the day-to-day running of the system. You must consider things such as fluid pumpability at cold temperatures, low fouling temperature, good thermal stability, non-corrosiveness to system materials and low fluid price. These all play a role in how your system will function during startups, operation and shutdowns. But the biggest impact is from choosing a low cost fluid. This can be a potential area where one will sacrifice fluid characteristics to meet a price point. The photograph shows the potential difference between a heat transfer fluid from a Group 1 base stock relative to a Group 2 base stock. Almost all Group 1 fluids are yellowish in color and almost all Group 2 fluids are tech white or water clear. All Group 2 fluids are highly refined and most often offer better heat transfer characteristics then Group 1 fluids.

"We see that customers choose a Group 1 base stock heat transfer fluid because of price, but end up realizing that they have to clean out their systems within two to four years," says Mark Smith, MultiTherm's general manager. "The fluid has degraded to the point that it starts to coat the interior components of the heat transfer fluid system, and they recharge with a fluid that provides longer fluid life and better thermal properties".

In summary, the ideal fluid for a heat transfer system has all the physical properties and addresses all the safety issues as well as all the operational issues. You can find that a mineral-oil hydrocarbon heat transfer fluid offers the best solution depending on your system requirements. So when you are considering your next fluid change-out or designing a new system, contact a manufacturer/distributor of non-hazardous, non-toxic Group 2 hydro-carbon based heat transfer fluids.

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Considering Safety

Among the considerations of choosing a heat transfer fluid is safety. As you fit the fluid to your application, assess these five fluid properties that affect their safe use.

    1. Non-hazardous or non-toxic

    2. Low vapor pressure

    3. High boiling point

    4. High flash point

    5. High auto-ignition temperature

"Most of these properties impact each other and definitely have an effect on the fluid's performance," says Mark Smith, general manager at MultiTherm in Devault, Pa.

For more information

Contact MultiTherm. Call (800) 339-7549 or visit www.multitherm.com/ph.

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