Often used in welding shops and oil refineries, the motor in these fans is rated as safe for use around flammable and combustible gas, vapor, and dust. As a belt-drive motor, it’s quieter than direct-drive motors and has a longer life span because its components are replaceable. The motor is totally enclosed for protection in dusty and damp environments. These fans are freestanding, so there’s no mounting required. They have wheels for rolling into place before they’re hardwired, but don’t allow for movement once they’re in use.