Water treatment glycol buying guide
September 13, 2023
By Shadi Salman

A Glycol Buying Guide for Closed Loops

Is All Freeze-Protection Made the Same? 

Most people know that you can use either Propylene or Ethylene glycol to freeze-protect a hot or chilled loop in their building. But there are other key differences to consider as well:

  • Should you use pure glycol or one that includes a corrosion inhibitor package?
  • What are the advantages of a concentrate vs. a product pre-mixed with water?
  • What kind of corrosion inhibitor should your product use?

Pure Glycol vs. All-in-One Products

Pure Glycol doesn’t have any additives. Some facilities will purchase pure glycol because they happen to find a cheap source, but then they need to supplement with inhibitors and buffers if they want to avoid corrosion and other issues.

All-in-One Products contain glycol plus corrosion inhibitors and pH buffers. If you choose the right blend for your system, you won’t need to purchase any extra additives to protect metal components or minimize the effects of glycol breakdown. 

Pre-mixed vs. Concentrate

Pre-mixed Glycol Solutions come already diluted with deionized water. This provides a potential shortcut to achieving the right percentage of glycol to water, but it has some practical downsides. You need to buy higher volume – up to 5 times as much – which means higher shipping charges and greater difficulty in transporting and storing. 

Concentrate Products are undiluted and pumped directly into your loop. It’s important to know your system water volume so you can use the right amount of concentrate. Assuming this prerequisite is met, concentrate product have some real advantages:

  • Easier and less expensive to transport
  • Easier to inject into your system
  • Allows you to dilute with hard water, providing both anodic and cathodic corrosion protection

Phosphate-based vs. Nitrite/Molybdenum-based Inhibitors

Phosphate-based inhibitors are widely used in glycol antifreeze. Phosphate is effective in preventing corrosion and providing a pH buffer, but it has its share of issues. The biggest is that it requires you to use soft or deionized water in your system. If you introduce hard water into your loop, the orthophosphate will interact with the calcium hardness to produce calcium phosphate scale.

Nitrite or Molybdenum-based inhibitors bring a greater level of versatility to glycol solutions. They provide corrosion protection and buffering levels comparable to phosphate, but can also be used with hard water, so a city water source is not an issue. 

Which Glycol Product is Right For You? 

Whatever product you choose, it’s a good idea to have someone knowledgeable assess the current condition of your closed loop system and your water/glycol solution before you spend additional money on freeze-protection. Glycol is rarely a set-it-and-forget-it kind of purchase – a trained eye to prescribe the right mix for the right variables, and then to help monitor solution stability and corrosion protection over time is always essential.

That being said, most facilities will find that an all-in-one glycol concentrate product with Nitrite/Molybdenum-based corrosion inhibitors provides the best combination of convenience, cost-efficiency, and long-term protection. HOH has designed their Pro-Kool and Gly-Kool product lines based on these specifications, making them an ideal product for a majority of closed loop needs. 

If you would like more information on HOH freeze-protection products, please don’t hesitate to contact us.