Maintenance Best Practices for Heat Transfer Fluid

Heat transfer fluid (HTF) plays an important role in thermal management. It helps keep indoor environments, production equipment, industrial facilities, and products within safe or desirable temperature ranges. However, its proper performance doesn’t just depend on choosing the right HTF for your application. You also need to pay careful attention to maintenance best practices.

 

In this discussion, we're joined by Old World Industries (OWI) product specialist Vache Soghomonian to discuss maintenance best practices for heat transfer fluid systems. Vache is a senior account executive at OWI and one of the company's top HTF experts.

 

Vache delivered these insights as part of Understanding Glycol-Based Heat Transfer Fluids, an informative webinar. His insights cover:

 

• The importance of regular testing
• How to prevent HTF system leaks
• Recommended system flushing practices
• Guidelines for safe HTF storage

 

Vache's guidance can help businesses save money by extending the lives of both their fluids and their HTF systems. His advice is specific to heat transfer fluid systems that use ethylene glycol (EG) or propylene glycol (PG) formulations. For some background info on these products, see our earlier post on heat transfer fluid and how it works.

 

 

The importance of regular testing

"I always equate HTF systems to the human body," Vache says. "You go to the doctor and get a physical, and it's almost the same idea with these systems." 

 

Testing involves having a lab analyze a sample taken from an active HTF system. "The more data points you have, the closer an eye you'll have on the system," Vache explains. "This will help you identify and understand where problems are occurring, and what you can do to correct those problems." 

 

As a best practice, Vache recommends testing your system every six months — once in spring and once in fall. At minimum, you should conduct lab testing at least once a year. If you opt for annual testing, have a sample analyzed before your system's peak operating season. This will help you identify and correct any potential issues before they have a chance to cause major problems.

 

 

HTF testing parameters

Lab tests analyze at least five different aspects of your heat transfer fluid:

 

Glycol concentration

Your HTF's glycol concentration target will usually fall between 30% and 70%, but it varies depending on manufacturer recommendations. The lab will test both your HTF's glycol concentration and its freeze point. These checks ensure your HTF is providing proper freeze and burst protection, and that it won't freeze at your system's minimum operating temperatures.

 

pH levels

"This is where you're going to bounce around between an acidic and a basic side," Vache explains. You don't want your pH levels to become too acidic at the lower end of the pH scale, as this can cause corrosion. You also don't want them becoming too basic at higher pH readings since it can cause scaling.

 

Target pH ranges usually fall between 8.0 and 10.5, depending on manufacturer recommendations.

 

Reserve alkalinity

Reserve alkalinity readings indicate how well your system is able to resist changes in pH levels. Specific reserve alkalinity targets vary, depending on product formulation. In any event, reserve alkalinity testing acts as a kind of early warning system that can identify deteriorating performance.

 

Inhibitor concentration

"Inhibitor concentration is super important as well," Vache stresses. "You don't want to have your inhibitor levels dropping and essentially running raw glycol through your system." Lab tests verify that your HTF's corrosion protection additives are still active and present in high enough quantities to do their job.

 

This test varies. Some products use a "pass or fail" system. For others, you'll need to check specific concentration levels to ensure they're within recommended ranges.

 

Visual inspection

As a final standard check, the lab will visually inspect your HTF. This is a check you can also do yourself, if you know what to look for.

 

Vache explains: "When you draw a sample out, is there any junk in there? Any scaling? Any orange or rust-colored deposits? If your fluid is dyed, you want to see it's still the color it's supposed to be."

 

Your HTF should be clear and free of particles or sludge. If it's cloudy or discolored, your system may be contaminated or heading toward a breakdown.

 

What should you do if testing reveals problems?

Here are immediate next steps Vache recommends if testing uncovers problems with your heat transfer fluid system:

 

Problem	Recommendation
Low glycol percentage	Add a concentrated HTF formula to restore proper gylcol levels The amount of concentrate you'll need depends on your lab results
Low pH levels	Flush and replace the fluid If the problem is minor, you can also recondition the fluid by:  Adding an inhibitor booster or compatible concentrate Removing dissolved oxygen from the system Filtering or flushing out particulates
Low inhibitor levels	Add an inhibitor booster or partially drain and refill the system with fresh fluid
Contamination	Perform a full system flush and fully replace your HTF

 

On the topic of system contamination, Vache says, "Whether it's bacteria growth or just a large amount of scale or rust that's occurring, you will certainly need to flush out the system with an acid wash, Then, cycle some water through it and reintroduce the glycol."

 

Once you've reintroduced the glycol, take a sample of the new fluid and have a lab analyze it to make sure it maintains its integrity.

 

 

How to prevent heat transfer fluid system leaks

A simple visual inspection can help you prevent serious leaks by detecting problems early. "Walk around the system. If you see any drips, take data points on them," Vache advises. Note the locations of the leaks and the color of the leaking fluid.

 

"We recommend installing a dyed fluid in the system," Vache says. "This helps you identify fluid leaks more easily."

 

As a general rule of thumb, you should have a qualified engineer or inspector perform this check at least once a week. If you're running a critical or high-temperature application, daily checks are safer. Some guidance even recommends having someone check for leaks during every work shift.

 

Recommended practices for flushing heat transfer fluid systems

When flushing out systems, different guidelines apply. The procedure you'll follow depends on whether your heat transfer system is new, or whether you're doing a drain-and-refill flush on a system that's been running for a while.

 

"For new constructions, use an alkaline-based chelating cleaner," Vache explains. "These are really good at getting out greases, solder, and any type of machine oils that may be in the system."

 

Systems that have a longer operational history need a different flushing agent known as mild acid chelating cleaner, or "acid wash." Simply run the acid wash through the system according to manufacturer recommendations, then reintroduce your glycol immediately afterwards.

 

Guidelines for safe heat transfer fluid storage

By packaging and storing your heat transfer fluid properly, you can extend your HTF's shelf life while also protecting its performance characteristics.

 

"If you receive the product in bulk, you can store it in bulk storage tanks," Vache says. "You can find tanks as small as about 3,000 gallons, or as large as 18,000 to 20,000 gallons." Vache also endorses using black steel drums to protect the HTF from ultraviolet (UV) light, which can degrade the fluid.

 

For smaller bulk quantities, Vache recommends tote bins — also known as intermediate bulk containers (IBCs). "Tote bins come in a variety of sizes," Vache notes. "They start as low as 275 gallons, and you choose from plastic or steel totes." 

 

No matter which bulk storage solution you choose, keep the product out of direct sunlight and in a well-ventilated area. Indoor storage is recommended whenever possible, but especially when outdoor temperatures fall below 10°F (-12°C).

 

Several special considerations apply to your various storage options, as summarized in the table below:

 

Storage Container Type	Consideration
Steel Tank	Rust may occur in the vapor space, since oxygen is present and there is no active inhibitor where condensation occurs. To prevent rust, you can keep the tank topped off at maximum levels or choose a tank with an epoxy or polymer interior coating.
Steel Drum	Ensure the drum's cap is always tightly secured to prevent air exposure. Air exposure can change your HTF's pH levels, inhibitor effectiveness, or freeze protection profile.
Tote bins/IBCs	Indoor storage is strongly recommended. Ensure the bin is not exposed to direct sunlight, and that its seal cap is applied tightly.

 

Charge forward with PEAK's state-of-the-art Thermal Charge HTF

To choose the right heat transfer fluid, you need to carefully consider your intended application and the performance characteristics your HTF must have. If a glycol HTF is the right choice for your needs, you can buy with confidence knowing that PEAK's Thermal Charge line of heat transfer fluids is available in affordable bulk quantities.

 

PEAK Thermal Charge heat transfer fluids deliver a long list of performance benefits, including:

 

• Advanced corrosion protection through specially engineered inhibitor packages
• Reduced system maintenance and fluid replacement needs
• Superior freeze and burst protection characteristics
• Excellent pH stability
• Extended product lifespans that protect fluid integrity for longer to deliver a superior return on your HTF investment

 

PEAK Thermal Charge allows you to customize your HTF solution with color options that make it easy to identify your heat transfer fluid in field settings. OWI can also create precise dilution percentages to optimize fluid performance for your specific application.

 

Finally, remember that OWI offers a fluid analysis program. Simply collect some fluid in an OWI-supplied sampling kit and send your HTF to our state-of-the-art lab for analysis. We'll provide a detailed explanation of the results that will eliminate guesswork and lay out clear next steps to follow if you encounter a problem.