Fan Filter Unit With Laminar Flow Hood
Fan Filter Unit With Laminar Flow Hood Based on considerations of production costs and system cleanliness effects and stability, the construction of Class 100 clean laminar flow areas in the modern pharmaceutical industry is basically built Fan Filter Unit With Laminar Flow Hood. Laminar flow hoods, due to a series of disadvantages and defects that are difficult to solve, have almost withdrawn from the mainstream of clean system construction.
----------------------------The clean system configured with a fan system has the following disadvantages----------------------------
Produce laminar flow. When a fan supplies air, due to the distance between the filter and the fan, the wind speed on the outlet surface will be very different. The air flow generated is turbulent and it is difficult to achieve laminar flow. The 100-level area requires air flow to flow strictly in the direction of laminar flow, so this method is difficult to make the system achieve perfect 100-level and laminar flow effects.
Fan aspect. The entire system has only one fan, which places very high demands on the fan! Once the fan fails, the entire system will be paralyzed and unable to operate. At this time, production must be stopped for maintenance. This will cause huge losses to manufacturers in the peak production season! The investment in the entire clean system cannot be compared with this loss. The high requirements for fans in Class 100 clean areas make it almost impossible to guarantee the reliability of the fans, and problems are inevitable.
Life span. In this system, the filter can only be installed in the press block type. Coupled with the influence of unstable wind speed and pressure, the traditional installation method will greatly reduce the life of the high-efficiency filter. The investment in system maintenance and cost is not worth it.
Sealing. Whether it is a medium-efficiency device in the box or a high-efficiency device at the end, leakage is easy to occur due to the limitations of the fixation method. There is no way to make up for the leakage of air flow. It is a fatal flaw for the entire system. It will directly affect the cleanliness of the system and increase the production cost of the manufacturer. Once a leak occurs, there is no point in installing a differential pressure gauge in the system.
Noise. Due to the high-intensity operation of the fan, the noise is very loud, reaching up to hundreds of decibels, affecting the production environment and workers' work, and even endangering the workers' health. This is undoubtedly a problem that cannot be ignored for enterprises where people are the first productivity. .
Maintenance. The high-efficiency filter adopts a pressure block fixation method. In order to ensure its sealing, it is not easy to replace the filter in the box. In order to protect the high efficiency, it has to be replaced frequently, so maintenance is not as simple as imagined.
----------------------------Hepa filter ffu has the following obvious advantages----------------------------
Each module is supplied with air by a fan. Due to the unique internal air duct design, it can ensure that the air flow speed on the outlet surface is between 0.35~0.45m/s, forming a stable laminar flow. If it is full in a hundred-level area, It can fully meet the cleanliness requirements of level 100.
Because each module has its own air supply part, even if one of them fails, it will not affect the operation of the entire system. Only the faulty module needs to be repaired. For manufacturers, maintenance is quick, does not affect the normal operation of the system, and its reliability and stability are very high.
Due to the unique structure and sealing method of each FFU, the filter does not need to bear other external forces during fixation and use, so the life of the filter will not be compromised. Our company's FFU modules use Swedish Camfil high-efficiency filters, which are generally used in 10,000-level environments and can last for 5 to 6 years without replacement. The extension of life saves system maintenance costs.
A fan corresponds to a high-efficiency filter, and a sealing device can be installed for the filter. The filter in the FFU is in close contact with the fan housing, will not leak, and can achieve a good sealing effect. No need to worry about a series of problems caused by leaks.
The fan has a relatively small burden. Coupled with the unique air duct silencer design, the noise generated during operation can be reduced to less than 53 decibels, which will not affect the normal production of line workers.
FFU adopts self-weight sealing, which not only achieves the sealing effect but also simplifies the installation and replacement time. You only need to lift the shell to replace the filter. The outer shell is only about 20 kilograms, which is light and easy to operate. Coupled with the low frequency of replacement every 4 to 5 years, it saves maintenance work.
For high-efficiency filters, especially in Class 100 clean areas, there is no need to install a differential pressure gauge. You only need to ensure that the air flow speed is between 0.35 and 0.45m/s to ensure cleanliness, so you only need to perform regular tests on this item. , simple and effective.
----------------------------Features----------------------------
FFU is the most ideal component of the clean room system in the electronics industry. It ensures cleanliness through air circulation filtration. It has the characteristics of mature product technology, convenient design and construction, and flexible operation and maintenance.
FFU product technology is relatively mature, the module is standardized, and it can better adapt to the size of ceiling keels; high-quality, high-efficiency, low-noise fans combine the high-efficiency filtration performance of HEPA/ULPA, which greatly extends the service life of FFU; large-scale group control The system makes FFU remote monitoring, centralized management, energy consumption control and other functions more complete.
FFU is easy to design and construct. When the cleanliness in the clean factory is adjusted regionally due to process changes, it can be adjusted by changing the FFU layout rate. FFU has its own power and can act as a negative pressure seal, so that the air supply static pressure box layer has a negative pressure relative to the clean factory building, and the particles in the static pressure box will not be affected by the pressure and leak into the clean area; compared with RCU+ HEPA system, MAU+FFU+DCC system occupies less floor height in the air supply static pressure box and basically does not occupy the clean room space; at the same time, it saves a lot of air duct production and installation projects and shortens the clean room construction cycle.
The FFU system is flexible in operation and maintenance. The FFU is a modular unit and the supporting filters are easy to replace. It has strong adaptability to process changes and the installation, replacement and movement of the FFU are flexible and simple. Group control adjusts the FFU fan speed and reasonably controls the frequency of filter replacement, which can effectively reduce FFU energy consumption reduces operation and maintenance costs.
----------------------------Main performance parameters----------------------------
The main performance parameters of FFU are: size (mm), surface wind speed (m/s), external residual pressure (Pa), noise (dBA), power consumption (W), vibration (mm/s), lifespan (hours), etc. .
Size
Module size (ceiling modular size), the spacing between the center lines of the ceiling keels. The commonly used standard module sizes of FFU are 1200x600mm (4"x2"), 1200x900mm (4"x3"), 1200x1200mm (4"x4"), among which The thickness is mostly 300-400mm.
The actual size of the FFU filter = module size - (keel section width - 25mm). The actual size of the fan module is slightly larger than the filter by 4mm. If the commonly used ceiling keel end face width is 55mm and the module size is 1200x600mm, the corresponding actual size of the FFU filter is 1170x570mm and the actual size of the fan module is 1175x575mm.
Face wind speed
The face wind speed of FFU is generally controlled at 0.3~0.5m/s.
Residual pressure outside the machine
The residual pressure outside the machine is the ability of the FFU to overcome the resistance of the circulating wind in the clean room. The residual pressure is related to the service life of the FFU and is closely related to the fan. At a certain wind speed, it can generally be calculated as follows: external residual pressure (ESP, the static pressure provided by FFU to overcome the resistance of external pipes and return air ducts) = total static pressure (TSP) - filter pressure loss (filtration pressure at this wind speed device resistance value).
The total static pressure, that is, the static pressure value that the FFU can provide when the maximum power and wind speed is zero, generally the AC FFU is around 300Pa, and the DC FFU is between 500-800Pa. High-efficiency filter pressure loss, according to the "High-efficiency Air Filter GB-T13554-2008" regulations, its maximum initial resistance at rated air volume is 250Pa. When the face wind speed is 0.35m/s, the residual pressure outside the FFU machine is about 100Pa. When the face wind speed is 0.45m/s, the static pressure outside the machine is not less than 90Pa.
Noise
According to the "Clean Factory Design Code GB50073-2013", it is clearly stipulated: "The airborne noise level in the clean room should not be greater than 60dB (A) in non-unidirectional flow clean rooms, and should not be greater than 65dB (A) in unidirectional flow and mixed flow clean rooms. A)". When considering the superposition of noise from multiple FFUs, it is not easy to ensure that the noise meets the specification requirements. At present, the noise of large-area unidirectional flow and mixed flow clean rooms using the FFU method generally exceeds 65dB (A) and is as high as 68-70dB (A).
Power consumption
The power consumption of AC FFU system is generally 100-300 watts; the DC system is about 50-220 watts. DC systems consume 30-50% less power than AC systems.
Vibration
The vibration rate is generally less than 1.0mm/s.
----------------------------Determine the air supply volume of the clean room----------------------------
Calculate the clean room air supply volume. Calculate the air supply volume determined based on heat and humidity load calculations and the total air volume that meets the air cleanliness level requirements, and take the maximum value.
| air cleanliness | air pattern | average wind velocity(m³/h) | ventilation rate |
| 1-3 | unidirectional flow | 0.3≈0.5 | ------ |
| 4-5 | unidirectional flow | 0.2≈0.4 | ------ |
| 6 | non-unidirectional airflow | ------ | 50≈60 |
| 7 | non-unidirectional airflow | ------ | 15≈25 |
| 8-9 | non-unidirectional airflow | ------ | 10≈15 |
Determine the FFU surface wind speed
Assuming the FFU surface wind speed, you can temporarily take the common surface wind speed values of 0.35m/s and 0.45m/s for FFU clean workshops in the electronics industry, and bring them into the calculation respectively.
Determine the FFU area area
Calculate the FFU area based on the assumed FFU surface wind speed and clean room air supply volume. The specific formula is: FFU area area = total circulating air volume/FFU section wind speed.
Determine the number of FFU
Combined with the professional decoration FFU ceiling layout, determine the FFU keel size and FFU module size, and then determine the FFU quantity. Number of FFU (N1) = FFU area area/FFU module size.
FFU typesetting
According to the layout of the FFU keel, arrange the clean area FFU reasonably. According to other professional conditions, avoid clean lamps, smoke exhaust outlets, etc., and consider the principle of aesthetics when layout the FFU.
----------------------------The economy of FFU choosing AC and DC modes----------------------------
FFU selects AC and DC forms, which is a requirement for the optional motor of FFU. FFU motors are divided into two types: AC (alternating current) and DC (direct current).
Comparison of initial power distribution costs
The operating current of the AC FFU fan filter unit is 1.5A-2.0A. A set of 4 square wires is connected to a 20A switch for 4 FFUs, while the operating current of the DC FFU fan filter unit is 0.2A-0.6A. A set of 4 square wires Connect 8 FFUs and save half the power distribution price.
Comparison of air-conditioning cost consumption
The average power of the AC FFU fan filter unit is 160W, and the average power of the DC FFU fan filtration unit is 60W. The average power of the DC FFU is 100W less than the AC FFU. Based on the conversion of 5% of the fan power into heat, the air conditioning consumed by the AC motor FFU is: The weight is 160X5^=0.008KW, and the amount of air conditioning consumed by the DC motor FFU is 60X5%=0.003KW.
----------------------------Fan Filter Unit With Laminar Flow HoodSummary----------------------------
Generally speaking, AC FFU is commonly used in Class 1000~100,000 clean rooms, while DC FFU is used in areas with higher cleanliness. High-grade clean rooms have stricter requirements for temperature and humidity. With DC FFU, software control can be applied with higher accuracy. Motors using three-phase AC power supply are prone to phase loss and motor burnout. Using a single-phase AC power motor will cause large size and unbalanced load. The use of DC motors has high construction costs and high operation and maintenance costs. FFU is the main engineering component of electronic clean rooms. With the rapid development of the electronics industry, it will surely drive the popularity of FFU applications.
Through the economic comparative analysis of the AC and DC modes used by FFU, it can be seen that the DC mode is more energy-saving than the AC mode. For Fan Filter Unit With Laminar Flow Hood with the same type of fans, FFU systems using PTFE filters are more energy-efficient than FFU systems using glass fiber filters. Calculated based on a face wind speed of 0.45m/s, in DC form FFU, the FFU system using glass fiber filters has 46w more power than the FFU system using PTFE filters, that is, the energy consumption is 30.8% higher.
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