Final answer:
The operating principle of a fire extinguisher is often described with the acronym PASS (Pull, Aim, Squeeze, and Sweep). The extinguishers utilize fluorinated solutions or foaming agents to spread across and extinguish fires, especially those involving organic liquids.
Step-by-step explanation:
The acronym commonly used to describe the operating principle of a fire extinguisher is PASS, which stands for Pull, Aim, Squeeze, and Sweep. However, when discussing the chemical principles involved, fire extinguisher systems usually rely on a fluorinated solution or other fire-suppressing agents to spread across a burning surface and extinguish the fire. Traditional fire-fighting foams work well against fires of organic liquids. It is important to note that certain substances like dry-cleaning solvent previously used in fire extinguishers are no longer recommended due to health and safety concerns. Additionally, foaming plastics can be part and parcel of fire extinguisher systems, aiding in quelling flames by cutting off the oxygen supply to the fire.