One of the most important aspects to consider when selecting a hot oil heater is the film temperature. Though this factor is incredibly important, many consumers do not ask about film temperature when selecting a design for a hot oil heater. They typically look at efficiency, burner turn down, controls and other aspects when evaluating the selection of industrial hot oil heaters they’re considering, but tend to overlook the film temperature.
So why is film temperature so important when it comes to industrial heating? Why should plant managers in the market for a new hot oil heating system inquire about film temperature when researching their options?
Why Film Temperature Matters in Industrial Hot Oil Heaters
Here are a couple of the key reasons why you should carefully consider film temperature when selecting a hot oil heater for your plant.
1. Hot Oil Heater Film Temperature Impacts The Type of Thermal Heating Fluid Required
The film temperature in a heater that has space between the tubes, such as American Heating Company’s Serpentine Coil Thermal Fluid Heater, is typically 50oF higher than the operating temperature. Most other industrial heater designs on the market use helical coils, which do not have space between the tubes. This lack of space causes uneven heat absorption in the pipe itself, creating a higher film temperature. The film temperature in a helical coil heater is typically 100oF higher than the operating temperature. So what does this mean?
It means that with a helical coil heater, you will most likely need to select a more expensive thermal heating fluid. If you are operating at 500oF, in a helical coil heater your film temperature will be 600oF or higher, requiring you to use a much higher grade fluid than you would need if you were utilizing a serpentine coil heater like those we manufacture here at American Heating Company.
At 550oF film temperature you can run a fluid in the $10-15/gallon range, but in the 600-650oF film temperature range you will need a synthetic fluid in the $40-55/gallon price range. This can have a significant impact when it comes to your facility’s expenses.
High film temperature 4,000 Gallon System x $55 per gallon of heating fluid = $220,000
Lower film temperature 4,000 Gallon System x $15 per gallon of heating fluid = $60,000
That is a $160,000 savings as a result of using a thermal fluid heater with a lower film temperature! Obviously this can vary depending on which brand of fluid you select, but you can see how it adds up!
2. Film Temperature Impacts Thermal Heating Fluid Life
The second aspect of having a lower film temperature is that the thermal heating fluid you select will last much longer than it would in a heater with a higher film temperature. The rule of thumb from fluid suppliers is that for every 10oC (18oF) increase in film temperature, the degradation rate in the fluid will double. Since the film temperature in an AHC hot oil heater with a serpentine coil is 50oF lower than its helical coil counterparts, you will see significantly less degradation in fluid.
As a result, many of our heaters are running with the same initial fill of fluid for 15-20 years, well past the estimated life of the heat transfer fluid!
For more details and to confirm these calculation, check out this article from Dow Chemical Company discussing film temperatures and how the grade of fluid has an effect on film temperature. In the article they calculate the film temperature of a helical coil heater and a serpentine coil heater that has space between the tubes, and confirm that heaters operate with lower film temperatures when a coil has space between the tubes.
Save Money Now and In the Future With Lower Hot Oil Heater Film Temperatures
There are many benefits that come from implementing an API style thermal fluid heater from American Heating Company in your facility. While mechanical benefits such as high efficiency, ease of repair, robust coil design, large combustion chamber, and longer coil life are all very important, perhaps one of the most significant benefits is the heater’s lower film temperature.
Interested in learning more about how our heaters with low film temperatures can help to save your facility money in the long- and short term? Give us a call today at (715) 748-5888 or contact us online for more information or to request a quote.
Additional Resources Related to Film Temperature:
Why Investing in High Grade Heat Transfer Fluid is a MUST – Learn about the value and benefits of high grade heat transfer fluid and why the added expense is worth it for most companies that rely on industrial heating equipment.
Why Your Hot Oil Heater is Burning Up Your Heating Fluid – Find out what’s causing your heating fluid to burn up in your thermal fluid heater and what you can do to prevent it moving forward.
Why Hot Oil Is Better Than Steam for Industrial Heating – Learn about the numerous benefits hot oil heating offers in comparison to steam boilers.