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Freez-Kontr'l HD

  • Heavy-duty 70% propylene glycol-based heat transfer formulation
  • Specifically designed for a higher operating temperature (325°F maximum)
  • Formulation provides better stability when mixed with water containing up to 350ppm total hardness in a closed loop application
  • Pink colored formulation to assist in system leak detection


Freez-Kontr’l HD is a heavy-duty 70% propylene glycol-based heat transfer fluid formulated for hydronic applications where its multi-component inhibitor formulation provides added robustness for better service life. The specially developed formulation achieves a higher maximum operating temperature of 325°F, higher reserved alkalinity, better thermal stability and added stability when mixed with water containing up to 350ppm total hardness in closed loop applications. Freez-Kontr’l HD is a pink colored solution to aid in system leak detection.

IMPORTANT: Due to ingredients used in its formulation, Freez-Kontr’l HD should NOT be used in refrigeration applications where there is a possibility of incidental contact with potable water or food. For these refrigeration applications, Nu-Calgon’s Freez-Kontr’l, Freez-Kontr’l 95/5, Freez-Kontr’l FG or Freez-Kontr’l 35 formulations must be selected due to their low acute oral toxicity.

Packaging Size Part Number Additional Info
Freez-Kontr'l HD - 5 gallon pail 4188-12


This product must be used in accordance to the following directions by HVACR professionals only.

  1. Clean new or lightly corroded existing systems with Nu-Calgon System Cleaner (4370-08) prior to installation of Freez-Kontr’l. Do not use with galvanized steel.
  2. Extensively corroded existing systems should be cleaned using an inhibited acid such as Season Start Scale Remover or Liquid Scale Dissolver. Job should be handled by an experienced serviceman. All necessary replacements and repairs should be made.
  3. The concentration of required glycol-based Freez-Kontr’l will depend on the kind of protection needed. There are two types of protection: burst protection and freeze protection. Burst protection prevents bursting or other mechanical damage, but it is not enough to keep solution pumpable. Freeze protection requires more glycol, and it prevents the formation of ice crystals at the lowest temperature experienced by the fluid. This assures fluid can be pumped at the lowest experienced temperature.
  4. Typically, ice storage systems, fire sprinkler systems and intermittently run hydronic systems may be fine with burst protection while chilled water and lawn sprinkler systems need freeze protection.
  5. See the chart and select the lowest expected ambient temperature, then go to a temperature 5ºF colder to assure protection. Decide on type of protection, and identify the solution percentage that must be made up of Freez-Kontr’l.
  6. Calculate or establish system volume in gallons, and multiply this volume by the percentage identified above. This will tell you the number of gallons of Freez-Kontr’l required.
  7. For optimum corrosion protection, a minimum concentration of 30% is recommended.

Product Information:

Literature Downloads

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Product Safety

RTK Information

2611 Schuetz Rd. St. Louis, MO 63043
  • Telephone: 800.554.5499
  • Email:
  • Hours: Mon–Fri: 8:00am - 5:00pm (Central Time)

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