What is a fire extinguisher? What is the substance used in the modern type of fire extinguishers? How is it an improvement over the soda-acid and foam-type fire extinguishers?

Fire extinguishers are devices in which carbon dioxide is produced in different forms to be used as an extinguishing agent.

Liquid carbon dioxide is the substance used in the modern type of fire extinguishers.

Modern type of fire extinguisher is an improvement over the soda-acid and foam-type fire extinguishers in the following ways:

1. Soda-acid fire extinguishers cannot be used for oil fire as the solution ejected being heavier than oil sinks below oil and does not work whereas modern type of fire extinguishers can be used to put out both oil-fed fires and electrical fires.
2. Both the soda-acid and foam-type fire extinguishers solutions are prepared in water which conducts electricity. It might generate an electric shock leading to short circuit and another fire. But in modern type fire extinguishers, liquid carbon dioxide is used which does not conduct electricity. So, it can be used to put out electrical fires.