How thick of HEPA can be installed on ultra-thin EFU?

If you answer this question directly with a number, you are probably wrong.

The available height of the EFU on the equipment side is determined by the equipment structure, and within this height, the fan, air duct, filter, sealing structure and installation tolerance must be inserted at the same time. How thick HEPA can occupy depends on how much space is left and whether the remaining space can meet the target air volume requirements. So the real question is not 'how thick can it be installed', but 'what filter element can be installed at this height to achieve the target wind speed'.

Do the height allocation first, don’t choose the filter element first

After getting the equipment drawings, the first thing is to disassemble the available total height:

The thickness of the bottom plate and top plate of the box, the height occupied by the fan and impeller, the air inlet and outlet diversion space, the thickness of the filter body, the required height of the sealing structure (gasket or liquid tank), and the required operating margin during disassembly and assembly.

The sum of these items must be less than the total height allowed by the equipment. A common approach is to determine the fan and air duct first, because they are subject to aerodynamic constraints and have little room for compression; the thickness of the filter element is relatively flexible - but flexibility does not mean choosing randomly.

One thing is easily overlooked: Just because the filter element can be put in, doesn't mean it can be taken out. Equipment covers, cables, safety doors, and moving parts may block the replacement path. If the core size is only statically assembled during the design stage, the prototype can be installed, but the filter element cannot be replaced on site by the customer. This situation is not uncommon in equipment-side projects.

The filter element is thin, what’s the cost?

Under the same external dimensions, making the filter element thinner means that the effective filtering area is reduced and the pleat space is compressed.

As the area decreases, the passing wind speed of the filter material will be higher under the same air volume, the resistance will increase, and the dust holding capacity will decrease. The performance is as follows: the initial wind speed may be okay, but after a period of operation, the resistance climbs quickly, the wind speed attenuates significantly, and the replacement cycle is shortened.

Therefore, a thin filter element is not as simple as 'flattening a thick one'. It requires targeted design in filter material selection and pleated structure. Some solutions try to maintain the effective area within a limited thickness by switching to low-resistance filter materials or adjusting the pleat density; some solutions accept higher resistance and use fans with higher static pressure to compensate.

Which one is suitable depends on how much height the equipment can give, what the target wind speed is, and how long the maintenance cycle is required. If any one of these conditions is missing, the selection will be impossible.

The thickness of the filter element and the target wind speed should be calculated together.

After determining the candidate thickness, you need to get the resistance data of the filter element at the target air volume, and then compare it with the available static pressure of the fan.

A common misunderstanding in this step is to only look at the initial resistance of the filter element. The resistance will rise after running for a period of time. If the initial resistance is just stuck at the edge of the fan's capacity when selecting the model, the wind speed will attenuate significantly in the later period. A reasonable approach is to leave a margin and include the final resistance conditions in the calculation.

If after calculation, it is found that no matter what filter element is selected within the available height, the target wind speed cannot be reached, then the problem is not with the filter element, but with the space provided by the equipment for the EFU itself which is not enough to support this goal. At this time, it is necessary to discuss again with the equipment side: whether the target area can be narrowed, whether the wind speed requirements can be relaxed, or whether there is room for adjustment in the equipment structure.

Different devices, different answers

The internal structures of semiconductor cleaning equipment, EFEM, and glue coating and development equipment are very different, and the available heights and air inlet conditions are different. Some devices have enough space reserved at the top to accommodate filters of regular thickness; some have tight space and can only use ultra-thin solutions.

Therefore, the question of 'how thick HEPA can be installed in ultra-thin EFU' can only be answered by placing it on specific equipment drawings. The general experience value is: first confirm the total height limit and the air inlet space, then back-deduct the required effective area of ​​the filter element based on the target air volume, and finally determine the feasible filter element structure at this height.

About Aili Industrial’s ultra-thin EFU package

Ai Li industrial The EFU equipment-side fan filter unit supports ultra-thin structure and small size customization, and can be matched according to the equipment drawings. HEPA/ULPA air filter . Since fans, motors, control systems, sheet metal and filters are in the same manufacturing system, height allocation and air volume calculations can be completed at the same time during the planning stage, eliminating the need to first determine the filter element and then find the fan.

For locations where space is particularly tight, the total height limit of the equipment, the position of the air inlet, the target surface wind speed, and the disassembly and assembly direction can be provided together to facilitate the judgment of whether the ultra-thin solution is feasible and the appropriate thickness of the filter element. When it comes to the sealing structure of the liquid tank, the tank body and knife edge dimensions also need to be checked at the same time. For details, please refer to liquid tank seal HEPA . Interface description of