The Fan Filter Unit (FFU) is a key purification device in clean rooms (controlled environments designed to minimize particulate contamination), dust-free workshops and other places. Its core function is to achieve local air purification by using a fan to push air through high-efficiency filters. These filters include HEPA (High-Efficiency Particulate Air, which captures very fine particles) or ULPA (Ultra-Low Penetration Air, which captures even smaller particles). According to different classification criteria, FFU can be divided into various types. The following are common classification methods and specific types: I. Classification by filter type
This is the most crucial classification method, which directly determines the filtering efficiency of the FFU:
Hepa-type FFU: Equipped with high-efficiency air filters (HEPA, which stands for High-Efficiency Particulate Air), it can achieve a filtration efficiency of over 99.97% for particles with a diameter of ≥0.3μm (micrometers, a micrometer is one millionth of a meter), and is suitable for most clean rooms (such as Class 1000 to Class 100,000, where the class indicates the maximum allowed particles per cubic foot).
ULPA type FFU: Equipped with ultra-high efficiency air filters (ULPA, or Ultra-Low Penetration Air), it can achieve a filtration efficiency of over 99.999% for particles with a diameter of ≥0.12μm (micrometers). It is suitable for scenarios with higher cleanliness requirements (such as Class 1 to Class 100 cleanrooms—lower numbers mean fewer particles, suitable for sensitive industries like semiconductors).
Ii. Classification by fan type
The fan is the power source of the FFU, and its type affects the energy consumption, noise and speed regulation performance of the equipment.
Centrifugal fan type FFU: It adopts a centrifugal fan, with relatively high air pressure and stable air circulation efficiency. It is suitable for large clean areas, but the noise is relatively slightly higher and the energy consumption is medium.
Axial flow fan type FFU: It adopts an axial flow fan, which has a large air volume but a relatively low air pressure. It is suitable for scenarios where the air pressure requirement is not high. It has lower noise and less energy consumption, but its filtration efficiency stability is slightly inferior to that of the centrifugal fan type.
Brushless DC fan type FFU: It adopts a brushless DC motor to drive the fan, featuring a wide speed regulation range (which can be controlled by PLC or stepless speed regulator), low energy consumption, long service life, and low noise. It is currently the mainstream high-end type and is widely used in precision electronics, medicine and other fields.
Iii. Classification by Installation Method
According to the layout and installation requirements of the cleanroom, it can be classified as:
Ceiling-mounted FFU: Directly embedded in the ceiling keel of the cleanroom, flush with the ceiling, it saves space and is aesthetically pleasing. It is the most common installation method and is suitable for standardized cleanrooms.
Bracket-type FFU: Fixed under the ceiling or above the ground through brackets, it is flexible to install, convenient for later maintenance and adjustment, and suitable for non-standardized clean areas or temporary clean requirements.
Laminar flow FFU: Multiple FFUs are combined to form a laminar flow hood, ensuring that a local area forms a vertical or horizontal unidirectional flow. It is suitable for workstations with extremely high requirements for local cleanliness (such as semiconductor wafer operation areas, operating rooms, etc.).
Iv. Classification by Control Mode
With the increasing demand for intelligence, the control methods of FFUs are becoming increasingly diverse:
Single manual control FFU: Each FFU is independently equipped with a speed control knob to manually adjust the air volume. It is suitable for small clean rooms or scenarios with low requirements for control accuracy, and has a relatively low cost.
Centralized control of FFU: Through a central control system (such as PLC, touch screen), the start, stop, and wind speed of multiple FFUs can be uniformly controlled. The operating status of each FFU (such as wind pressure, filter resistance, fault alarm, etc.) can be monitored in real time. It is suitable for large clean rooms and is convenient for management and energy conservation.
Intelligent interlocking FFU: It combines sensors (such as differential pressure sensors, particle counters) to achieve automatic regulation. When the cleanliness or differential pressure deviates from the set value, it automatically adjusts the fan speed to maintain a stable clean environment. It belongs to the high-end intelligent type and is widely used in precision manufacturing, biomedicine and other fields.
V. Classification by External Dimensions
The size of the FFU usually matches the ceiling module. Common standardized sizes include:
1200mm×600mm (most commonly used, suitable for most ceiling keel spacings);
1200mm×1200mm, 600mm×600mm, etc., can be combined and used according to the area of the clean room.
Different types of FFUs have their own advantages and disadvantages. When making a choice, factors such as cleanliness requirements, energy consumption budget, installation environment, and control needs should be comprehensively considered. For instance, semiconductor workshops typically opt for ULPA type + brushless DC fans + intelligent centralized control FFUs to meet the requirements of ultra-high cleanliness and precise control. In contrast, ordinary electronic assembly workshops may adopt HEPA type + centrifugal fan + single-unit controlled FFU to balance cost and performance.
This is the most crucial classification method, which directly determines the filtering efficiency of the FFU:
Hepa-type FFU: Equipped with high-efficiency air filters (HEPA, which stands for High-Efficiency Particulate Air), it can achieve a filtration efficiency of over 99.97% for particles with a diameter of ≥0.3μm (micrometers, a micrometer is one millionth of a meter), and is suitable for most clean rooms (such as Class 1000 to Class 100,000, where the class indicates the maximum allowed particles per cubic foot).
ULPA type FFU: Equipped with ultra-high efficiency air filters (ULPA, or Ultra-Low Penetration Air), it can achieve a filtration efficiency of over 99.999% for particles with a diameter of ≥0.12μm (micrometers). It is suitable for scenarios with higher cleanliness requirements (such as Class 1 to Class 100 cleanrooms—lower numbers mean fewer particles, suitable for sensitive industries like semiconductors).
Ii. Classification by fan type
The fan is the power source of the FFU, and its type affects the energy consumption, noise and speed regulation performance of the equipment.
Centrifugal fan type FFU: It adopts a centrifugal fan, with relatively high air pressure and stable air circulation efficiency. It is suitable for large clean areas, but the noise is relatively slightly higher and the energy consumption is medium.
Axial flow fan type FFU: It adopts an axial flow fan, which has a large air volume but a relatively low air pressure. It is suitable for scenarios where the air pressure requirement is not high. It has lower noise and less energy consumption, but its filtration efficiency stability is slightly inferior to that of the centrifugal fan type.
Brushless DC fan type FFU: It adopts a brushless DC motor to drive the fan, featuring a wide speed regulation range (which can be controlled by PLC or stepless speed regulator), low energy consumption, long service life, and low noise. It is currently the mainstream high-end type and is widely used in precision electronics, medicine and other fields.
Iii. Classification by Installation Method
According to the layout and installation requirements of the cleanroom, it can be classified as:
Ceiling-mounted FFU: Directly embedded in the ceiling keel of the cleanroom, flush with the ceiling, it saves space and is aesthetically pleasing. It is the most common installation method and is suitable for standardized cleanrooms.
Bracket-type FFU: Fixed under the ceiling or above the ground through brackets, it is flexible to install, convenient for later maintenance and adjustment, and suitable for non-standardized clean areas or temporary clean requirements.
Laminar flow FFU: Multiple FFUs are combined to form a laminar flow hood, ensuring that a local area forms a vertical or horizontal unidirectional flow. It is suitable for workstations with extremely high requirements for local cleanliness (such as semiconductor wafer operation areas, operating rooms, etc.).
Iv. Classification by Control Mode
With the increasing demand for intelligence, the control methods of FFUs are becoming increasingly diverse:
Single manual control FFU: Each FFU is independently equipped with a speed control knob to manually adjust the air volume. It is suitable for small clean rooms or scenarios with low requirements for control accuracy, and has a relatively low cost.
Centralized control of FFU: Through a central control system (such as PLC, touch screen), the start, stop, and wind speed of multiple FFUs can be uniformly controlled. The operating status of each FFU (such as wind pressure, filter resistance, fault alarm, etc.) can be monitored in real time. It is suitable for large clean rooms and is convenient for management and energy conservation.
Intelligent interlocking FFU: It combines sensors (such as differential pressure sensors, particle counters) to achieve automatic regulation. When the cleanliness or differential pressure deviates from the set value, it automatically adjusts the fan speed to maintain a stable clean environment. It belongs to the high-end intelligent type and is widely used in precision manufacturing, biomedicine and other fields.
V. Classification by External Dimensions
The size of the FFU usually matches the ceiling module. Common standardized sizes include:
1200mm×600mm (most commonly used, suitable for most ceiling keel spacings);
1200mm×1200mm, 600mm×600mm, etc., can be combined and used according to the area of the clean room.
Different types of FFUs have their own advantages and disadvantages. When making a choice, factors such as cleanliness requirements, energy consumption budget, installation environment, and control needs should be comprehensively considered. For instance, semiconductor workshops typically opt for ULPA type + brushless DC fans + intelligent centralized control FFUs to meet the requirements of ultra-high cleanliness and precise control. In contrast, ordinary electronic assembly workshops may adopt HEPA type + centrifugal fan + single-unit controlled FFU to balance cost and performance.
