What should I do if the air volume is insufficient after using the H14 filter in the EFU?

After the equipment-side EFU is replaced with H14, the air volume is insufficient, which is a typical problem in semiconductor equipment matching. Different from the FFU on the ceiling of the clean room, the EFU is installed inside the equipment, and the space for moving is very limited, and the processing ideas are also different.

Let’s talk about the conclusion first: don’t rush to adjust the speed first. The EFU air volume is insufficient, and filter resistance is only one of the possible reasons. Equipment air inlet space, air outlet obstruction, and air duct path may all be limiting conditions. Looking in the wrong direction and adjusting the speed often just push the problem back.

First figure out what you need from the equipment

EFU serves local areas inside the equipment, such as the wafer transfer area and near the cavity opening. What these areas need is not 'large wind volume', but to maintain stable wind speed and airflow coverage at specific locations.。

Therefore, the first step is not to look at the air volume number of the EFU itself, but to go back to the equipment drawings to confirm: how much range the target area needs to cover, what surface wind speed is required, and what the allowed wind speed fluctuation is. Once these data are determined, we can infer how much air volume the EFU needs to provide and how much static pressure is required in this air path.

Many judgments of 'insufficient air volume' are actually due to the fact that the target itself is not quantified - we only know that it is smaller than the original, but we don't know whether it is small enough to be used.

The resistance of the filter element should be viewed along the entire air path.

H14 generally has higher resistance than H13, no doubt about that. But the actual available static pressure of EFU does not just look at the filter element.

For the EFU inside the equipment, the air inlet is often close to the rack, cables, moving parts and even the safety cover. The air outlet side may have a guide structure or directly face a sensitive area. These will eat up some of the static pressure. The resistance of the filter element plus the resistance of the box, air inlet, air outlet and equipment interface is the total resistance that the fan really has to overcome.

When calculating this account, you need to get the resistance data of H14 at the target air volume, and then compare it with the PQ curve of the EFU fan. If the new operating point has deviated from the range corresponding to the target wind speed, it means that the selection level does not match, and it is of little significance to discuss speed adjustment at this time.

Several directions when space is limited

The filter area of ​​the EFU is limited by the opening of the equipment, which is a hard constraint. When the air volume is not enough, the directions that can be evaluated are roughly as follows:

Replace with a filter element structure with a larger effective filtration area. Under the same dimensions, the resistance may be different by adjusting the pleats or structural form. Provided the internal depth of the equipment allows.

Adjust fan configuration. Under the allowable height and electrical conditions of the equipment, evaluate whether there are fan options with higher static pressure. However, it should be noted that increasing the fan capacity does not mean solving the problem - if the bottleneck is in the air inlet space or the air outlet is blocked, the effect of replacing the fan will be limited.

Optimize the internal air path of the equipment. Check whether the air inlet is blocked by cables or air pipes, and whether the air outlet side is facing the structural parts to form a backflow. This type of change usually does not require replacement of parts, but requires the cooperation of the equipment factory to adjust the structure.

Recheck the target area. If the equipment structure determines that the EFU can only cover some areas, you can consider narrowing the target range so that the EFU can focus on serving the most sensitive locations and handle the remaining areas separately.

No one of these paths is necessarily correct, it depends on the actual constraints of the equipment. The key is to first confirm where the bottleneck is and then choose a direction.

The processing logic is different from that of FFU

on the ceiling The FFU fan filter unit has relatively ample upper space, good air inlet conditions, and more means to deal with air volume issues. The EFU is installed in the equipment, and the available height, air inlet space, and maintenance path are all determined in advance, leaving much less room for modification.

Therefore, in the EFU selection stage, it is necessary to make it clear: how much height the equipment can provide, where the air inlet is, what obstructions are around, and what wind speed is required in the target area. The more complete these inputs are, the better it can be determined at the drawing stage whether the H14 can be used or whether the structure needs to be changed. There is no need to wait until the prototype is installed to discover that the air volume is insufficient.

About Aili Industrial’s EFU package

Ai Li industrial The EFU equipment-side fan filter unit supports ultra-thin structure and small size customization, and can be matched with HEPA/ULPA air filters are used, and fans, motors, control systems and filters are matched in the same manufacturing system. This means that filter element resistance, fan static pressure and available equipment space can be calculated together during the planning stage, instead of looking back to find problems after the entire machine is installed.

For equipment that is already in operation and needs to be switched to H14, equipment drawings, available heights, target air volumes and existing EFU parameters can be provided to facilitate judgment whether the filter element selection needs to be adjusted or the internal air path of the equipment needs to be optimized. Involving the position of the liquid tank sealing structure, the interface size can also be checked together. For details, please refer to Instructions for liquid tank sealing HEPA .