We all know that during the operation of the FFU or laminar flow hood, how to properly protect it is a very important issue. Actually, properly maintaining and caring for the FFU laminar flow hood can effectively increase the lifespan of the FFU fan filter unit and save certain costs for the company.
Nowadays, Clean Workshop has listed the relevant maintenance precautions for the FFU laminar flow hood as follows:
1. Based on the cleanliness level of the environment, the FFU fan filter unit should replace the filter (initial efficiency usually lasts for 1-6 months, high efficiency usually lasts for 6-12 months, and high-efficiency filters cannot be cleaned).
2. Regularly (usually every two months), use a dust particle counter to measure the cleanliness of the clean area that has been purified by this product. When the measured cleanliness does not match the required cleanliness, the cause should be identified (whether there is leakage, whether the high-efficiency filter is ineffective, etc.). If the high-efficiency filter is ineffective, a new high-efficiency filter should be replaced.
3. When replacing the high-efficiency filter and the initial filter, the machine should be shut down for the replacement.
4. When replacing the high-efficiency filter of the FFU fan filter unit, pay attention to the following matters:
1. When replacing the high-efficiency filter of the FFU filter unit, pay special attention to ensuring that the filter paper is intact during unpacking, transfer, and installation. Do not touch the filter paper with your hands to avoid damage.
2. Before installing the FFU, inspect the new high-efficiency filter with your eyes to check if it is damaged due to transportation or other reasons. If there are gaps in the filter paper, it cannot be used.
3. When replacing the high-efficiency filter of the FFU, first lift the box, then remove the failed high-efficiency filter, replace it with a new high-efficiency filter (make sure the airflow arrow mark of the high-efficiency filter is in the same direction as the air flow direction of the purification unit), and ensure that the frame is sealed before putting the box cover back in place.
Proper maintenance of the FFU laminar flow hood can save a lot of costs for replacing high-efficiency filters, so owners should pay attention.
The FFU is a laminar flow outlet with its own fan (unenclosed fan). It is combined with its dedicated bracket system, pressurizing fan, cooling coil, fresh air system, and dedicated lamps to form the FFU system. That is, the fan and filter (high-efficiency filter or ultra-high efficiency filter) are combined to form an end purification device that can provide power itself. In the past, the efficient filter outlets, self-cleaning devices, laminar flow hoods, etc. commonly used in clean engineering were all types of FFU. When choosing and installing FFU, pay attention to the following issues.
1. Noise control
The fan of the FFU is usually operated by several or even dozens of parallel units. When designing, it is necessary to consider the cumulative noise of the FFU to ensure that "the noise level (in idle state) in the clean room should not exceed 60 dB, and for unidirectional flow, mixed flow clean rooms, it should not exceed 65 dB" as stipulated in the "Clean Room Factory Design Specification GB50073-2001". Therefore, when choosing the fan, select high-performance, pressure-out type, direct-drive radial blade fans, which can reduce the overall noise.
2. Selection of the fan housing
When choosing the structure of the FFU fan housing, not only should the avoidance of fan leakage and the elimination of damage during transportation and transfer be considered, but also the ability to be disinfected with disinfectants and the environment in which the FFU is used should be considered. Therefore, stainless steel or aluminum alloy materials should be used as the housing.
3. Selection of the bracket
Because the fan filter unit of the FFU is directly installed in the ceiling bracket, in order to make the filter easy to replace and ensure the balance of the FFU fan operation while reducing the probability of installation imbalance. Therefore, professional matching bracket systems should be considered. This dragon frame is made by mechanically cold-rolling special geometric shapes (U-shaped) of steel plates. The metal surface is treated for corrosion prevention according to different environmental conditions (such as electrostatic spraying, hot and cold galvanizing, epoxy, etc.), which ensures the strength similar to that of channel steel and meets the requirements of FFU operation.
4 Selection of control methods
Currently, FFU usually adopts single-phase multi-speed AC motors, three-phase multi-speed AC motors and DC motors. The supply voltages of the motors are approximately four types: 110V, 220V, 270V, and 380V. The control methods mainly include the following types:
(1) Multi-speed switch control system: This system only includes an on-off switch and a power switch provided by the FFU. Since the control elements are provided by the FFU and distributed in various positions within the clean room ceiling, the staff must adjust the FFU on-site by turning the switch to control it, which is extremely inconvenient and the adjustable range of the FFU's wind speed is limited to a few levels. The advantage of the multi-speed switch control method is that the control is simple and the cost is low, but it has many drawbacks: for example, high energy consumption, inability to smoothly adjust speed, no response signal, and inability to achieve sensitive group control.
(2) Continuous speed adjustment control: This system is compared with the multi-speed switch control method. It adds a continuous speed controller, allowing the FFU fan speed to be continuously adjustable. However, it also sacrifices the motor power, making its energy consumption higher than the multi-speed switch control method.
(3) Computer control: Compared with the previous two methods, the computer control method has the following functions: it can not only adopt distributed control methods but also conveniently complete the centralized monitoring and control of FFU, and can conveniently complete the single-unit, multi-unit, and zone control of FFU. In addition, it can set the control system's reserved communication interfaces to communicate with the upper computer or network, then complete remote communication and management functions.
(4) Remote control: This remote control method as an addition to the computer control method can be used to control each FFU with a remote controller, complementing the computer control method. When choosing these control methods, they should be selected based on the actual situation.
5 Maintenance and management of FFU
When using the FFU air supply method, usually not a single device but dozens or hundreds of FFUs are installed on the ceiling. Therefore, it brings certain difficulties to maintenance and management. Usually, the high-efficiency filters are replaced from the clean room, while the fans mostly need to be protected at the top of the dragon frame (inside the static pressure box). However, if the static pressure box does not have sufficient height to protect the fan from the inside, then it is necessary to consider the feasibility of protecting the fan from the inside of the clean room. In conclusion, when using FFU, it is necessary to think according to the actual situation to retain its characteristics and reduce costs.
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