Which of the following is NOT considered an obsolete extinguisher type?

Water mist fire extinguishers are a newer technology designed to combat various classes of fires, making them a valid and effective option for modern firefighting needs. They work by discharging fine water particles that absorb heat and displace oxygen, suppressing the fire without causing additional damage. This type of extinguisher is now commonly used in many environments, especially where equipment or materials may be sensitive to water, like in data centers or museums.

In contrast, the other types mentioned are considered outdated. Soda acid and chemical foam extinguishers have largely fallen out of favor due to advancements that provide improved effectiveness and safety. Vaporizing liquids are also seen as less modern and can pose additional risks due to their flammability and handling requirements. This context underscores why water mist is not obsolete, but rather a current and viable option in fire safety.