Where Are Fan Filter Units (FFUs) Suitable for Use?

A Fan Filter Unit is a modularised end-of-line air purification device with a built-in power unit that performs filtration. The fan draws in air to be purified from the top of the unit, which is then filtered through the filter and evenly distributed through the outlet, thereby meeting the air quality requirements of clean rooms.

FFU Fan Filter Unitsare widely used in clean rooms, clean benches, clean production lines, modular clean rooms, and other locations, as well as in semiconductor, electronics, flat panel display production lines, and other locations with strict requirements for controlling airborne contaminants.

Components of an FFU

An HEPA Fan Filter Unit typically consists of a centrifugal fan, a filter (high-efficiency particulate air (HEPA) filter or ultra-low-pass air (ULPA) filter), a housing, a controller, and other components.

Housing

The housing is primarily made of materials such as cold-rolled steel with baked paint, stainless steel, and aluminium-zinc-coated steel. Different materials are selected based on the specific application environment. The housing comes in two shapes: one with a sloped top, which primarily serves to guide airflow, facilitating the smooth and even distribution of incoming air, and the other in a rectangular prism shape, which is aesthetically pleasing and allows incoming air to come into contact with the filter surface over the largest possible area.

Coarse-efficiency filter

The coarse filter is primarily designed to prevent debris generated during construction, maintenance, or other activities from damaging the high-efficiency filter. It is typically made of washable polyurethane fibre.

Fan Impeller

Fan impellers come in two forms: forward-curved and backward-curved. Forward-curved impellers enhance the radial flow of air, improving dust removal efficiency; backward-curved impellers reduce energy consumption and minimise noise.

High-efficiency filter High-efficiency filters are primarily used to capture particles ranging from 0.1 to 0.5 µm in size, as well as various suspended particles.

Electronic components

The control of FFU Fan Filter Unit can be broadly categorised into multi-stage control, stepless control, continuous adjustment, and computer control. These systems also enable single-unit control, multi-unit control, zone control, fault alarms, and historical record functions.

During operation, the fan draws air in from the top of the FFU and filters it through a coarse filter and a high-efficiency filter using a unique air duct.

The filtered clean air is uniformly discharged across the entire outlet surface at a wind speed of 0.45 m/s ± 20%. Key design parameters include: surface wind speed, power consumption, wind speed uniformity, external static pressure, total static pressure, noise, vibration rate, etc.

FFU Classification

FFUs are categorised into the following major types based on differences in enclosure material, motor type, control method, unit static pressure, and filter efficiency:

FFUs are categorised by enclosure material into standard coated steel plates (including galvanised, aluminium-zinc coated, and powder-coated) (code G), stainless steel plates (code S), aluminium plates (aluminium alloy plates) (code A), and other materials (code O).

Based on motor type, they are divided into AC motors and brushless DC motors. Single-phase AC motors are designated as A1, three-phase AC motors as A3, and brushless DC motors as EC. Based on control method, they are divided into single-condition units (designated as S) and multi-condition control units (designated as M).

Based on unit static pressure, they are classified into standard static pressure type (designation S) and high static pressure type (designation H). Based on filter efficiency, they are classified into high-efficiency filters (designation H) and ultra-high-efficiency filters (designation U). If the unit inlet is equipped with a coarse-efficiency pre-filter, it is designated as P.

FFU Features

• Flexibility

• Small footprint

• Cost-effective

• Uniform and stable airflow

• Negative pressure sealing

Therefore, FFU Fan Filter Units are suitable for use in medical clean rooms, semiconductor, electronics, and flat panel production lines.