What type of explosions is caused by fuel gases or dusts?

The correct answer refers to non-seated explosions, which are typically caused by the combustion of fuel gases or dusts. Non-seated explosions occur when a flammable mixture, such as gas or dust suspended in the air, ignites and rapidly expands. This type of explosion does not require a confined space or the presence of an ignition source to be seated; instead, it results from the quick reaction of the combustible material with an oxidizer.

Fuel gases, such as natural gas or propane, and combustible dust, like that from wood or grain, can create an explosive atmosphere under the right conditions. When mixed with air and ignited, they can create a powerful shock wave resulting from the rapid release of energy. The atmosphere needs to reach a specific concentration of these gases or dusts along with an adequate source of ignition for a non-seated explosion to occur.

In contrast, other types of explosions, such as BLEVE explosions, involve the failure of pressurized vessels exposed to heat, leading to the violent release of superheated liquid vapor. Mechanical explosions are typically associated with the physical failure of machinery, not requiring combustion of gases or dust. Seated explosions generally refer to those that occur in confined spaces where the explosive mixture is “seated