The Importance of Inhibited Glycols

The Case of the Vanishing Contractor 

Daniel Cohen 
Market Developer - Dow Glycol Heat Transfer Fluids 

Using "inhibited" glycol fluid in its HVAC system without knowing the strength or weakness of the inhibitor, or even where the fluid came from, has been proven disastrous to a hospital. A contractor purchased 7,000 gallons of "ethylene glycol plus inhibitor" from a local distributor and was also contracted to return the fluid once a year to test and ensure that it retained the proper amount of inhibitor.

As it turned out, the fluid was rarely tested after the original fill. Years had passed without getting the annual fluid checkup and a concerned maintenance staff attempted to contact the contractor, only to find that the company had gone out of business. Because the defunct contractor was the only party to deal with the fluid distributor, the hospital had no way of determining where the fluid came from. The only identifying words on the drums were "ethylene glycol inhibited," with the word "inhibited" written in with a marker pen.

A new contractor was brought in; however, the origin of the fluid still could not be tracked down. Faced with an HVAC system running a mysterious fluid of unknown origin and quality, the new contractor called a local Dow distributor for help. The only thing the contractor knew for sure was that it wasn't a Dow fluid. However, the contractor valued the Dow distributor's experience with glycols.


Preventing Shutdowns with Dow Thermal Fluids

The Dow distributor recognized the drums as those of a small distributor known for making home brews - straight ethylene glycol and an inhibitor of its own - and marketing it as a product equivalent to Dow fluids. The home-brew distributor even went so far as to name its product "EG SR-1."

The Dow distributor sent a fluid sample to Dow's Thermal Fluids Testing Laboratory for analysis. In a week's time, the lab sent back a written report stating that the fluid was in poor condition and unable to provide adequate freeze and burst protection. In fact, the lab found enough sediment in the sample to confirm that the inhibitor content was virtually depleted.

If left undetected, the remaining straight ethylene glycol and water eventually would have corroded and rusted out the pipes, requiring replacement. A potential shutdown of the system was averted. All the analysis and reporting were done by Dow free of charge without any promise from the contractor to purchase a Dow fluid. Because there was too much scaling and sediment in the piping to allow partial draining and fluid replacement, Dow recommended a complete cleaning of the system and a total fluid change-out.

The new contractor handled the draining and flushing, then filled the system with a 40% solution of DOWTHERM™ SR-1 inhibited ethylene glycol-based fluid and 60% deionized water.

The Dow fluid has been in the system for three years. To ensure proper maintenance of the system, the fluid is analyzed every year by Dow, free of charge.

Just four years after filling its HVAC system with poorly inhibited ethylene glycol-based fluid, the hospital had been forced to incur the cost of another total fill. However, in the three years since DOWTHERM™ SR-1 fluid was put in, no problems have been reported. And in light of the confirmed ability of Dow glycol-based fluids to provide effective freeze, burst and corrosion protection for 20 years or more with proper inhibitor maintenance, no problems requiring another unexpected change-out are foreseen.

Why Choose a Dow Heat Transfer Fluid?

Dow Heat Transfer Fluids are made out of the highest quality ingredients, backed by detailed analytical and performance data from the world's leading chemical manufacturer.

DOWFROST™ is a specially formulated propylene glycol with highly engingeered inhibitor packages to prevent corrosion & galling in a range of closed loop heat transfer systems.  DOWFROST™ is widely used in water-based HVAC, process heating & cooling in both industrial & food manufacturing.  DOWFROST™ is made from DOW PuraGuard Propylene Glycol USP/EP with a specified purity of greater than 99.8%, allowing the fluid to last longer than the competition & reduce overall fluid expense. 

The quality of the glycol thermal fluid you select will have a direct bearing on the long term performance and maintenance of your systems. You can never be sure if you have both adequate freeze and corrosion protection which leads to inadequate maintenance and you may be compelled to replace your fluid frequently which eventually becomes expensive operationally

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