Which factor increases the risk of a dust explosion when a solid is finely divided?

Which factor increases the risk of a dust explosion when a solid is finely divided?

• A. Larger particle size
• B. Decreased ventilation
• C. Smaller particle size
• D. Higher moisture

Answer: (C)

The main idea is that how finely the solid is divided controls how easily it can form a combustible dust cloud. When particles are very small, they have a much larger total surface area and can remain suspended in air more readily. That combination—a fine dust cloud in the presence of oxygen and an ignition source—lets the reaction propagate rapidly and cause an explosion. So, smaller particle size increases the risk because it creates a more easily ignitable, more reactive mixture. Larger particle size reduces that risk because there’s less surface area exposed and less tendency for the dust to stay suspended as a cloud. Higher moisture would dampen the dust and make ignition harder, while decreased ventilation can increase risk by allowing dust to accumulate, but the direct, primary driver here is the small particle size.

The main idea is that how finely the solid is divided controls how easily it can form a combustible dust cloud. When particles are very small, they have a much larger total surface area and can remain suspended in air more readily. That combination—a fine dust cloud in the presence of oxygen and an ignition source—lets the reaction propagate rapidly and cause an explosion. So, smaller particle size increases the risk because it creates a more easily ignitable, more reactive mixture.

Larger particle size reduces that risk because there’s less surface area exposed and less tendency for the dust to stay suspended as a cloud. Higher moisture would dampen the dust and make ignition harder, while decreased ventilation can increase risk by allowing dust to accumulate, but the direct, primary driver here is the small particle size.