What risk is associated with Class K residue on floors or drains?

• A. It can increase traction hazards
• B. It easily dissolves in water
• C. It can be corrosive; avoid disposal down drains and follow proper cleanup procedures
• D. It evaporates harmlessly

Answer: (C)

Class K residue is caustic and can be corrosive. The potassium acetate-based extinguishing agent that remains after use can irritate skin and eyes and, more importantly, damage metal surfaces and drainage systems if it goes into pipes or sewers. Because of this, it should not be dumped down drains or into the sewer. Instead, clean up the residue with absorbent material, follow the manufacturer’s cleanup guidance, and dispose of the waste according to local regulations. The main concern here isn’t just slipperiness or how it behaves in water; the corrosive nature of the residue and its potential impact on plumbing make proper cleanup and disposal essential.