FFU, an abbreviation for Fan Filter Unit, is a self-contained air filtration system equipped with a powered fan. It serves as a highly efficient filtration and air supply device, representing a modular type of terminal air supply unit. FFUs are typically equipped with both preliminary and high-efficiency filters. Air is drawn in from the top through the fan, passes through these filters, and is then delivered as clean air at a uniform velocity.

Structurally, FFUs can be classified based on their motor type, including AC motors and brushless DC motors. AC FFUs often utilize five-speed regulators or stepless speed regulators, while DC systems incorporate control chips within the motor, allowing for remote control via specialized software, computers, control gateways, and network lines.

FFUs are widely used in various applications requiring high-level cleanliness, such as dust-free rooms, dust-free operation benches, dust-free production lines, assembled dust-free rooms, and localized Class 100 cleanliness areas. They are also essential in environments with stringent air quality requirements, including data centers, hospital operating rooms, and biological laboratories.