Foams are defined by expansion and subdivided into what three ranges?

Foams used in fire suppression are characterized by their ability to expand and fill spaces, which is crucial for effectively smothering fires and preventing re-ignition. The classification of foams into low, medium, and high expansion is based on the ratio at which air is introduced into the foam solution.

Low expansion foams typically create a dense blanket of foam that can adhere to surfaces and is effective for smothering liquid fires, such as those involving flammable liquids. Medium expansion foams offer a balance, generating a foam that can cover larger areas but still maintain enough density to stay in contact with surfaces to provide protection and extinguishment. High expansion foams produce large volumes of foam that are useful for filling spaces, such as basements or cargo holds, where the foam can blanket the fire and cut off the oxygen supply.

This classification is essential for firefighters and facility fire brigades, as the specific type of foam used can significantly impact the effectiveness of fire suppression efforts based on the fire scenario. Understanding these distinctions allows facility fire brigade members to select the appropriate foam for varying environmental and fire conditions, ensuring a more effective response to fire incidents.