Final answer:
The multi-purpose fire extinguisher typically referred to is the ABC fire extinguisher, which uses a dry chemical formula suitable for various types of fires. Due to environmental and toxicity concerns, safer alternatives to historical substances like bromine-containing compounds are being researched.
Step-by-step explanation:
The multi-purpose fire extinguisher that is commonly used is known as an ABC fire extinguisher. This type uses a dry chemical formula consisting of monoammonium phosphate, which can extinguish class A (ordinary combustibles), class B (flammable liquids), and class C (electrical) fires. The extinguisher's chemical agent discharges as a fine powder that can blanket a fire, effectively smothering it. Historically, other substances such as bromine-containing compounds have been used in fire extinguisher systems, and foaming agents, which were once a common addition to fire protection strategies. However, due to their toxic impact on the environment, scientific efforts are ongoing to develop safer substitutes. This is in line with older materials such as fluorinated solutions, which could spread across burning surfaces to extinguish fire, but may also pose environmental challenges.