by Grant Lobdell, General Manager

Freezing temperatures can wreak havoc on installations not designed to handle such conditions.  Beyond inspecting the equipment for damage and proper operation, the performance of the foam concentrate itself is often questioned after freezing temperatures.

Freezing of foam concentrate should be avoided but if it occurs, in most cases, the product will maintain its performance once thawed.  However, foam products that have been frozen should be inspected for signs of separation as some ingredients may come out of solution as a result of the freezing and/or thawing process.  If separation is observed, the product should be mechanically mixed if possible.  If mixing does not return the product to a homogenous state or mixing is not possible*, the product may need to be replaced.  If there is ever any doubt in the performance of the product after such an event, laboratory testing to verify foam quality may prove beneficial even if not required.  The manufacture’s technical datasheet can also be consulted for more specific details on storage and handling recommendations.

If there continues to be concerns over freezing temperatures where the foam concentrate is stored, consider utilizing a foam concentrate listed for use at low temperatures if possible**.  At Underwriters Laboratories Inc. (UL) using UL 162 Foam Equipment and Liquid Concentrates as the standard for the evaluation of foam concentrates, UL categorizes foam products into one of the following minimum storage temperatures:

·        -20°F (-28.9°C)

·         0°F (-17.8°C)

·         20°F (-6.7°C)

·         35°F (1.7°C)

As part of the listing process, UL verifies that the product can flow through the equipment at its categorized minimum storage temperature to achieve not less than 85% of the quantity produced from the same equipment at 60°F (15.6°C) or higher.  The UL listing information or manufacturer’s technical data can be consulted to determine the minimum storage temperature for any product.

If you have any questions regarding this article, please contact Dyne Fire Protection Labs at or (800) 632-2304.

*Mineral oil, often placed on the top of foam concentrate stored in atmospheric tanks to prevent solvent evaporation, should not be mixed into the concentrate.

**Bladder tank type proportioners are only tested at 35°F (1.7°C).

©Dyne Fire Protection Labs 2021