Which hazard is described as dangerous when wet?

Which hazard is described as dangerous when wet?

• A. Flammable Solids Division 4.2
• B. Flammable Solids Division 4.3
• C. Toxic Substances Division 6.1
• D. Infectious Substances Division 6.2

Answer: (B)

Some hazmat solids are labeled dangerous when wet because water triggers a chemical reaction that releases a flammable gas. This describes the group of flammable solids that, upon contact with water, emit flammable gas. An example is calcium phosphide reacting with water to produce phosphine gas, which is both flammable and toxic, creating a dangerous situation when the material is wet. Other categories—solids that ignite spontaneously in air, or substances that are simply toxic or infectious—do not specifically describe this moisture-triggered gas release, so they aren’t the hazard described as dangerous when wet.

Some hazmat solids are labeled dangerous when wet because water triggers a chemical reaction that releases a flammable gas. This describes the group of flammable solids that, upon contact with water, emit flammable gas. An example is calcium phosphide reacting with water to produce phosphine gas, which is both flammable and toxic, creating a dangerous situation when the material is wet.

Other categories—solids that ignite spontaneously in air, or substances that are simply toxic or infectious—do not specifically describe this moisture-triggered gas release, so they aren’t the hazard described as dangerous when wet.