A unique consideration in controlling ____ substances is that the temperature of the released material may alter the properties of the surfaces or tools being used.

• A. Reactive
• B. Cryogenic
• C. Corrosive
• D. Toxic

Answer: (B)

Extreme cold from cryogenic substances means the released material can chill surfaces and tools so quickly that their properties change. Materials contract at very low temperatures, and metals can become brittle and susceptible to fracture under impact or stress. Coatings may crack, seals and gaskets can lose elasticity, and adhesives or elastomers may fail. Lubricants can solidify or become too viscous to function, making tools harder to operate. Condensation from the cold vapor can form ice on equipment, altering friction, grip, and heat transfer. These temperature-driven changes are unique to cryogenic hazards, which is why cryogenic considerations stand apart from reactive, corrosive, or toxic substances, where the main concerns are chemical reaction, material degradation, or health effects, respectively.