The role of FFU air purifier in clean spaces

FFU air purifier is a mobile air filtration device. It is used to remove harmful air particles from circulating air, providing purified air for clean rooms, laboratories, medical facilities, or microenvironments. These units are installed within the ceiling or floor grid of the system. Large cleanrooms require a large number of FFUs, which may range from several hundred to several thousand in some cases. The device typically includes its own pre filter, HEPA filter, and internally controllable fan air distribution.

FFU is usually made of steel casing and can be placed in ceiling grid brackets of similar size. The device typically includes a pre filter as well as HEPA (High Efficiency Particulate Air), ULPA (Ultra Low Particulate Air), or other MERV (Low Efficiency Reporting Value) filters. Electric fans are used to extract air through filters for distribution to rooms or enclosed workstations, such as fume hoods. The fan speed is usually controlled by a stepper or variable resistor motor, and the required level of cleanliness determines the filter used: HEPA filters remove particles of 0.3 μ m or larger with 99.99% efficiency, while ULPA filters remove particles of 0.12 μ m or larger with 99.999% efficiency.

FFU is designed for laminar airflow, where controlled air flowing in a consistent direction and velocity (carrying particles) in the environment is cleaner than turbulent air flowing in multiple directions or at non-uniform velocities. The eddies generated by turbulent air can cause pollution particles to deposit on clean surfaces.
The FFU air purifier is designed to be placed in a ceiling grid bracket of similar size. A ceiling grid with standard sized compartments that match the FFU size is used to construct a cleanroom. According to the cleanliness requirements of the controlled space, more fan filter units can be added to the grid to meet the ISO standards for airflow velocity and air exchange rate per hour.

FFU air purifiers can be used to replace more traditional circulating air units, such as ducts or pressurized air systems. Due to the need for space above the ceiling grid for FFU (FFU modules are 13 inches in size, plus an additional 1-2 feet of “empty” inflation space), pressurized ventilation systems are typically used in cleanrooms with height restrictions; They are air systems in layouts with smaller internal floor sizes. In addition, when the number of filters installed in the room is less than 20, fan driven FFU air purifiers are generally considered cheaper than traditional duct supply systems.
When clean air is needed in a microenvironment, FFU air purifiers can be used to construct enclosed workspaces or laminar flow cabinets. Applying the same principle as larger cleanroom grids, FFUs can be directly placed in independent grids above spaces that require clean air. This method is commonly used in silicon wafer etching in the semiconductor industry.