Industrial FFU is widely used in air purification in clean rooms. FFU (fan filter unit) is a combination of fan and filter, which can also be called "filter equipment with fan". FFU is usually installed at the air supply end of the clean room and is generally placed on the hoisting "dry" gasket sealing keel frame. The upper part of FFU is fan module and the lower part is filter.
According to the requirements of cleanliness, the air filter can be high efficiency (HEPA) or ultra high efficiency (ULPA) filters of different grades to provide clean air for the clean room. In addition to overcoming the resistance of the HEPA filter at the lower part of FFU, the fan module also needs to overcome the resistance of all channel components of the whole circulating air, so as to maintain the set operating wind speed. FFU system has the characteristics of simple design and construction, flexible wind speed regulation and easy change of clean area. It has become one of the popular system forms of industrial clean room.
First, flexibility. Because the FFU has its own power, it is not limited by the region. In a large clean workshop, it can be controlled by zones according to needs. Moreover, with the change of production process of the production line, the plant layout must be adjusted accordingly. The flexibility of FFU makes such adjustment easy and will not bring secondary investment.
Second, reusability. Theoretically, FFU equipment not used temporarily can be removed, sealed, properly kept and reserved for next use.
Third, negative pressure ventilation. This is the unique feature of FFU. Because it can provide static pressure, the air supply static pressure box has negative pressure relative to the clean room. So the particles in the static pressure box will not leak into the clean area under the action of pressure, making the sealing very simple and safe.
Fourth, shorten the construction cycle. The use of FFU saves the production and installation of bellows, because the air duct accounts for a large construction cycle in the cleaning project. Any investor hopes that the investment can bring benefits as soon as possible. The selection of FFU has become a better choice.
Fifth, reduce operating costs. Although the initial investment in the selection of FFU is higher than the use of air duct ventilation, in its later operation, it has the characteristics of energy saving and maintenance free, and the operation cost can be reduced by 40% with large circulation.
Key parameters of FFU system:
Module size: the spacing between the center lines of the ceiling keel. The standard module sizes commonly used by FFU are 1200 * 600 (4 '* 2'), 1200 * 900 (4 '* 3') and 1200 * 1200 (4 '* 4').
Actual size: the actual size of FFU filter = module size - (keel section width - 25mm), and the actual size of fan module is slightly 4mm larger than that of filter. For example, the end face width of the commonly used dome keel is 55mm, the module size is 1200, 900,600, the actual size of the corresponding FFU filter is 1170, 870, 570, and the actual size of the fan module is 1174, 874, 574.
External residual pressure: at a set wind speed, the external residual pressure (ESP) is the total static pressure (TSP) of the fan module minus the resistance of HEPA / ULPA filter. ESP is the ability of the FFU to overcome the circulating air resistance in the clean room. Whether it is to mark the external residual pressure of the FFU or the total static pressure tsp of the fan module, it must name the supply air speed or air volume, otherwise it is meaningless.
Input energy consumption: the product of input voltage and input current during normal operation of FFU. Obviously, the input energy consumption of FFU is different at different operating conditions, that is, at different operating air volume and total static pressure. Therefore, if the operating condition point is not specified, it is meaningless to enter the energy consumption value.
Noise: according to IES-RP-CC002, the noise value at 1.2m directly below the center of the air outlet surface during normal operation of FFU. The noise of FFU is different at different operating conditions, i.e. different operating air volume and total static pressure. Therefore, if the operating point is not specified, the noise value is meaningless.
Micro vibration: according to the standard IES-RP-CC002, the vibration amplitude and vibration rate of FFU at the maximum operating condition point.
Air supply uniformity: according to IES-RP-CC002, when FFU is in normal operation, measure the wind speed point by point on a horizontal plane 150mm (6 ") below the air outlet surface to obtain the average wind speed. The deviation ratio between the average wind speed and the maximum wind speed and the minimum wind speed is the air supply uniformity. IES-RP-CC002 requires that the deviation between the supply wind speed at any point of FFU and its average wind speed shall be within + / - 20%.
Filter efficiency grade: according to European standard EN1822, the filter grade is H10-H14, U15-U17, or the efficiency value of 0.3um according to American Standard MIL-282 (HEPA); According to American Standard IES-RP-CC007.1, for the efficiency value of 0.12um.