What type of fire extinguisher shall be used when servicing LOX?

• A. Water extinguisher
• B. Dry chemical extinguisher
• C. 125-150 lb PKP or equivalent placed within 50 feet
• D. CO2 extinguisher

Answer: (C)

When servicing liquid oxygen, the surrounding atmosphere is highly oxidizing, so any ignition source must be knocked down quickly with a non-aqueous extinguishing agent. A large dry chemical extinguisher using PKP (125–150 lb) or an equivalent agent, kept within about 50 feet, provides the fastest and most reliable fire suppression in this setting. PKP works by interrupting the chemical reactions occurring in the flame and forming a barrier between fuel and oxidizer, which is ideal for fires that could involve hydrocarbons or energized equipment. Water-based extinguishers are avoided around LOX because water can react violently with liquid oxygen, increasing risk, and CO2 extinguishers, while useful in some situations, are less effective for rapid knockdown in an oxygen-enriched environment and pose asphyxiation hazards in enclosed areas.