What is the substance called that is contained in a portable fire extinguisher and puts out the fire?

The term that describes the substance contained in a portable fire extinguisher that is used to effectively put out a fire is called the extinguishing agent. This agent can vary depending on the type of fire extinguisher and the specific class of fire it is designed to combat. Common extinguishing agents include water, foam, dry chemical, carbon dioxide, and other specialized materials, each selected for their effectiveness against different types of fires.

Understanding the role of the extinguishing agent is crucial for proper firefighting techniques, as each agent works differently to suppress flames. For example, water cools the fire, while dry chemical agents interrupt the chemical reaction occurring in the fire or displace oxygen.

The other terms may refer to different components of a fire extinguisher; for instance, a propellant is involved in expelling the extinguishing agent but does not itself extinguish the fire. The dry charge is a term often associated with the dry chemical extinguishing agents but does not encompass all types. Anhydrous materials typically refer to substances without water, which may be relevant in certain contexts but are not a general term for the active component that puts out fires in portable extinguishers.