The fan filter unit is abbreviated as “FFUâ€, which is a high-efficiency filter air supply port with a blower (without shell fan). It is combined with its special keel system, pressurized fan, cooling coil, fresh air system and special lamps to form the FFU system. . That is, a fan and a filter (high-efficiency filter or ultra-high efficiency filter) are combined to form an end-purifying device that can provide power. In the past, the air supply port, the self-cleaning device and the laminar flow hood of the high-efficiency filter with a fan commonly used in the clean engineering are all one of the FFU. The following issues should be noted when selecting and installing the FFU.
Noise control
FFU fans are generally used in parallel for several or even dozens of units. When designing, the stacking of FFU noise should be considered to ensure that the noise level (empty state) in the clean room is clearly defined in the Cleanroom Factory Design Code GB50073-2001. The unidirectional flow clean room should not exceed 60dB, and the unidirectional flow, mixed flow clean room should not exceed 65dB". Therefore, when selecting a fan, it is best to choose a high-performance, extrusion-type, direct-drive rear radial vane fan, which can reduce the overall noise.
Selection of fan casing
When selecting the structure of the FFU fan casing, it is necessary to consider not only to avoid the leakage of the fan and to eliminate the damage caused during transportation and handling, but also to consider the disinfectant disinfection and the environment used by the FFU, so it is best to use stainless steel or aluminum alloy. The material is used as the outer casing.
Skeleton selection
Since the fan filter unit of the FFU is directly installed between the ceiling frames, in order to make the filter easy to replace, it is necessary to balance the operation of the fan of the FFU and reduce the probability of installation imbalance. Therefore, the professional supporting dragon skeleton is generally considered. This kind of dragon skeleton is a steel which is mechanically cold-rolled into a special geometry (U-shaped). The metal surface is treated with anti-corrosion treatment according to its environment (such as electrostatic spraying, hot-dip galvanizing, epoxy, etc.), which can guarantee The strength of similar channel steel meets the requirements of FFU operation.
Choice of control method
At present, FFU generally adopts single-phase multi-speed AC motor, three-phase multi-speed AC motor and DC motor. The supply voltage of the motor is roughly 110V, 220V, 270V, 380V. The control methods are mainly divided into the following types:
(1) Multi-speed switch control system: This system only includes one speed switch and one power switch that the FFU comes with. Since the control elements are self-contained by the FFU and distributed in various positions in the ceiling of the clean room, the staff must adjust the FFU through the shift switch at the scene, which is extremely inconvenient to control, and the wind speed of the FFU can be adjusted within a limited range. . The advantages of using multiple-speed switch control methods are simple control and low cost, but there are many defects: for example, high energy consumption, smooth speed regulation, no feedback signal, and inability to implement flexible group control.
(2) Continuous speed adjustment control: Compared with the multi-speed switch control mode, the continuous speed adjustment control of this system has an additional continuous speed regulator, which makes the FFU fan speed continuously adjustable, but at the same time sacrifices the motor efficiency, enabling it to The consumption is higher than that of the multi-speed switch control.
(3) Computer control: Compared with the previous two methods, this system has advanced functions of computer control: not only can adopt distributed control mode, but also can realize centralized monitoring and control of FFU, and it can also realize FFU conveniently. Single, multiple and zone control. In addition, the control system can be set to reserve a communication interface, which can communicate with the host computer or the network, thereby realizing remote communication and management functions.
(4) Remote control: This system remote control mode is a supplement to the computer control mode. Each FFU can be controlled by the remote control, which is complementary to the computer control mode. These kinds of control methods should be selected according to the actual situation when selecting.
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