After the thickness of FFU filter is changed, why should we recheck the fan and maintenance structure?
Thickness changes are not just a matter of size
During FFU filter selection or replacement, filter thickness changes are sometimes encountered. For example, a 50 mm thick filter was originally used and was replaced with a 70 mm or 100 mm filter. Some projects believe that as long as the length, width and efficiency levels are the same, changes in thickness will not affect use.
This kind of thinking tends to ignore the knock-on effects of thickness changes. After the filter thickness is changed, the effective filter material area, resistance characteristics, sealing and compression method and replacement space may all change. These changes will affect the fan operating point, sealing effect and maintenance operations of the FFU.
Therefore, after the filter thickness is changed, the fan and maintenance structure need to be rechecked. Aili Industry has complete production capabilities in FFU complete machines and high-efficiency filters, and can provide matching confirmation on the interface between filters and complete machines. For the basic structure of the FFU machine, please refer toAili Industrial FFU fan filter unit。
How thickness affects effective filter media area and resistance
The increase in filter thickness usually means that more pleated filter media can be accommodated and the effective filtration area increases. Under the same air volume, as the filter material area increases, the wind speed passing through the filter material decreases, and the resistance may decrease. This may be beneficial to reduce FFU fan load and extend filter life.
However, as the thickness increases, the overall resistance characteristics of the filter will change. If the working point of the FFU fan is not rechecked, the air volume may be too large or too small. A larger air volume may increase energy consumption and air flow disturbance, while a smaller air volume may affect cleanliness.
When the thickness decreases, the effective filter material area may decrease and the resistance may increase. If the FFU fan static pressure margin is insufficient, the air volume may decrease. Therefore, whether the thickness increases or decreases, the working point of the FFU needs to be rechecked.
How thickness affects seal compression
The way the filter is sealed is related to its thickness. Gasket seals, liquid tank seals and knife edge seals have different requirements on the filter frame and thickness. If the filter thickness changes, the original pressing mechanism may not be able to press properly.
For example, when a 50 mm filter was originally used, the pressing mechanism was designed for 50 mm. If you change to a 70mm filter, the pressing mechanism may not be able to close, or the sealing strip may not be compressed enough. If you replace it with a thinner filter, the pressing mechanism may be over-tightened, causing deformation of the sealing strip or damage to the filter frame.
Sump seals are also sensitive to thickness changes. The knife edge insertion depth, liquid tank position and filter frame structure need to match the thickness. If the seal structure does not match after the thickness changes, leakage may occur.
How Thickness Affects Maintenance Space
Changes in filter thickness will affect the removal space inside the FFU. For pull-down FFUs, where the filter is removed from below, the increased thickness may require greater operating clearance. If the installation height of the FFU is limited, thicker filters may not be removed or installed smoothly.
For top-loading FFU, thickness changes may affect the operating space in the suspended ceiling mezzanine. If mezzanine clearance is limited, thicker filters may not be able to flip or move inside the FFU.
Therefore, when replacing the filter thickness, it is necessary to confirm the suitability of the FFU maintenance structure and installation space. If there is insufficient space, you may need to choose a different thickness or adjust maintenance methods. Please refer to the maintenance space check of the detachable FFU.Detachable FFU。
How to recheck the fan operating point
After the filter thickness changes, the fan operating point needs to be rechecked. The verification includes: the resistance of the filter under the target air volume; the static pressure capacity of the FFU fan under this resistance; the air volume and power at the actual working point; and the change in the working point after dust accumulation on the filter.
If the FFU adopts constant speed control, the air volume will change after the filter resistance changes. If constant air volume control is used, the fan power will change with the resistance. No matter which control method is used, it is necessary to confirm whether the working point is within a reasonable range.
For projects that require precise air volume, on-site air speed measurements can be performed after the filter is replaced to confirm that the actual air volume is consistent with the target. If the air volume deviation is large, it may be necessary to adjust the FFU speed or change the fan configuration.
How to confirm machine matching
After the filter thickness is changed, the matching of the whole machine needs to be confirmed from the following aspects. Whether the installation dimensions of the filter and FFU box match; whether the sealing method is compatible; whether the pressing mechanism adapts to the new thickness; whether the maintenance space is sufficient; whether the fan working point is reasonable; whether the performance of the filter after dust accumulation is acceptable.
If the project usesThe FFU is equipped with a ULPA ultra-high efficiency filter . You should confirm that the interface between the filter and the FFU is consistent. If the project also requires chemical filtration, you can refer toFFU Chemical Filters understand the stacking effects of thickness and resistance.
Issues that should be confirmed in advance during project communication
During the FFU filter thickness change stage, it is recommended to confirm the following with the manufacturer: filter length and width dimensions and efficiency level; filter thickness and frame structure; sealing methods and requirements; whether the pressing mechanism adapts to the new thickness; whether the maintenance space is sufficient; whether the fan working point is rechecked; the performance of the filter after dust accumulation; whether on-site wind speed retest is required.
If you are considering changing the FFU filter thickness, you can visitAili Industrial FFU fan filter unit to learn about the complete machine configuration, you can also refer toHEPA and ULPA filters Learn about filter products of different thicknesses and structures, or contact Aili Industrial for support in matching filters and complete machines.
in conclusion
After the thickness of the FFU filter is changed, the effective filter material area, resistance, sealing compression and maintenance space may all change. Filter elements with the same efficiency level and the same length and width do not mean they can be unconditionally interchangeable. After the thickness is changed, the fan working point, sealing structure and maintenance space need to be rechecked.
Aili Industry has complete production capabilities in FFU complete machines and high-efficiency filters, and can provide matching confirmation on the interface between filters and complete machines. If you need to know more about FFU filter matching, you can visitAili Industrial FFU fan filter unit , you are also welcome to contact Aili Industrial for project support.
