Direct answer: Uneven air speed at the EFU outlet is usually not caused by a single reason. It needs to be checked in the order of 'fan position → filter status → structural shielding → system resistance'. If the fan is positioned eccentrically or too close to the filter, it will cause a local high-speed zone; if the filter resistance is unevenly distributed or poorly sealed, it will cause wind speed deviation on the windward side; if the internal structure of the box, bracket or cable is blocked, it will change the direction of the airflow; if the system resistance is abnormal, it will affect the overall working point of the fan. During the investigation, it is recommended to measure the wind speed distribution first, and then confirm it item by item based on the structure.

Uneven air outlet speed will directly affect the air supply coverage effect of the clean area. In severe cases, it may also cause local cleanliness to be substandard. The analysis will be carried out from three main directions below.

1. First confirm the manifestations of uneven wind speed

Before investigating the cause, it is recommended to first clarify the actual manifestations of uneven wind speed. Different manifestations often correspond to different causes:

After clarifying the manifestations, we can then investigate the three aspects of fan, filter and structure in a targeted manner.

2. The influence of fan position on wind speed uniformity

The position of the fan is one of the important factors that affects the wind speed distribution of the EFU outlet. Frequently asked questions include:

1. The fan is installed eccentrically : the center of the fan does not coincide with the center of the filter, and the air outlet is biased to one side;

2. The fan is too close to the filter : the air flow has no time to diffuse, forming a local high-speed area;

3. Uneven layout of multiple fans : The spacing between multiple fans is unreasonable, and the air supply overlaps or interferes with each other;

4. The air outlet direction of the fan does not match the box : the air flow forms eddy currents or biased flows in the box;

5. Inconsistent fan speeds : When multiple fans are configured, differences in the speeds of each fan lead to uneven wind speeds.

Improvement directions include: adjusting the installation position of the fan to align it with the center of the filter, increasing the diffusion distance between the fan and the filter, optimizing the layout spacing of multiple fans, and unifying the speed of multiple fans through the control system. For equipment that requires speed adjustment, please refer toThe DC EFU equipment fan filter unit solution matches the fan operating status through the control system.

3. Effect of filter on wind speed uniformity

The status of the filter directly affects the wind speed distribution on the windward side. Common problems include:

1. Uneven filter resistance distribution : The filter material is unevenly folded or partially damaged, resulting in local resistance differences;

2. Poor filter sealing : the edge sealing is not tight, and the airflow passes through the gap in a short circuit;

3. The filter installation is uneven : the fitting surface between the filter and the box is uneven, causing local air leakage;

4. The filter grade does not match the fan : a high resistance filter is equipped with a low static pressure fan, and the overall wind speed is low and unevenly distributed;

5. The filter size does not match the box : the filter is too small or too large, affecting the airflow distribution on the windward side.

Improvement directions include: confirming that the filter specifications match the box, checking the compression amount and fitting surface of the sealing strip, and replacing the filter with even resistance distribution if necessary. For equipment that requires frequent filter replacement, please refer toThe snap-on EFU filter fixing structure ensures that the sealing surface can still remain stable after repeated disassembly and assembly.

4. The impact of structural shading on wind speed uniformity

Structural obstruction inside the equipment and inside the EFU box is also a common cause of uneven wind speed:

1. Brackets or ribs inside the box : change the direction of local airflow;

2. Cables and pipes pass through the air outlet area : causing local turbulence;

3. The internal mechanical structure of the equipment is blocked : the air outlet surface is partially blocked by the mechanical arm and module;

4. The air inlet is restricted : the air inlet area is insufficient or the position of the air inlet is offset, resulting in uneven air intake;

5. The air outlet surface does not match the device interface : the air outlet surface is partially blocked, and the actual effective air supply area is reduced.

Improvement directions include: optimizing the internal structural layout of the box, moving cables and pipes out of the air outlet area, adjusting the EFU installation position to avoid obstruction, and redesigning the air outlet interface if necessary. For equipment with limited space, please refer toStructural ideas of the fan filter unit of small-sized EFU equipment , confirm whether the internal diffusion space meets the requirements.

5. System resistance and fan working point inspection

If the above three aspects are confirmed to be normal and the wind speed is still uneven, you need to check the system resistance and fan operating point:

1. Whether the final resistance of the filter is high : the resistance rises after dust collection, and the working point of the fan deviates;

2. Is the air inlet resistance too large ? The air inlet area is insufficient or the protective net is too dense;

3. Whether the air outlet is blocked : whether there is additional resistance between the air outlet surface and the device interface;

4. Whether the fan speed is stable : whether there are fluctuations in the power supply, control signal or the fan itself;

5. Whether there is air leakage in the system : there is air leakage from the box welds, interfaces or sealing surfaces, resulting in low local wind speed.

During the investigation, it is recommended to measure the air volume, static pressure and electrical parameters in the complete machine state to confirm whether the actual working point of the fan meets the design expectations.

6. Summary of methods to improve uneven wind speed

7. Suggestions for acceptance of wind speed uniformity

For wind speed uniformity issues, the acceptance method should be agreed upon during the design stage to avoid deviations after delivery:

1. Measurement plane : a section at a certain distance from the air outlet surface, the specific distance is agreed upon by the project;

2. Number of measuring points : calculated based on air supply area, at least 1 measuring point for each filter;

3. Judgment value : clarify the average wind speed and allowable deviation range;

4. Measure working conditions : confirm the actual operating status of the equipment and filter status;

5. Recording method : Record wind speed and unevenness at each measuring point for easy traceability.

8. Information required for troubleshooting EFU wind speed unevenness

It is recommended to provide: when communicating with the project:

1. Equipment installation space and EFU installation method;

2. Target air supply area and allowable wind speed;

3. Measured wind speed distribution data;

4. Filter specifications and usage time;

5. Fan model and control method;

6. Box structure and internal layout;

7. Internal occlusion of the equipment;

8. Acceptance measurement method requirements.

9. Aili Industrial EFU wind speed uniformity supporting capabilities

Aili Industrial has the following supporting conditions in terms of EFU wind speed uniformity:

• Fan matching : self-produced EC/DC/AC motors and fans, the fan position and parameters can be matched according to the box structure;

• Self-produced filters : With HEPA/ULPA filter production capabilities, the filter resistance consistency can be controlled;

• Structural design : The internal structure and diffusion space of the box can be designed according to the equipment space;

• Whole machine verification : conduct wind speed, air volume and operation tests before leaving the factory;

• Customization ability : The cabinet, air inlet and outlet methods and interfaces can be customized according to the equipment space.

For more EFU product systems, please refer toEquipment-side fan filter unit (EFU)、Custom EFU and70mm ultra-thin EFU。

FAQ

What are the common causes of uneven EFU air outlet speed?

Common reasons include eccentric position of the fan, too close the fan to the filter, uneven filter resistance distribution, poor filter sealing, obstruction of the internal structure of the box, restricted air inlet, and high system resistance.

What should be checked first for uneven wind speed?

It is recommended to measure the wind speed distribution first to identify the manifestations of unevenness, and then investigate in the order of fan position, filter status, structural obstruction and system resistance.

Does the fan position have a big impact on the uniformity of wind speed?

The impact is greater. If the fan is installed eccentrically or too close to the filter, it is easy to form local high-speed areas and biased flow.

Will a poorly sealed filter cause uneven air speed?

meeting. Poor sealing will cause air flow short circuit, local wind speed is low, and also affect the filtration effect.

How to improve structural occlusion?

This can be improved by removing obstructions, optimizing the internal structure of the box, adjusting the EFU installation position, or redesigning the air outlet interface.

How to check the uniformity of wind speed?

The measurement plane, number of measurement points, judgment values ​​and measurement conditions should be agreed upon during the design stage, and the wind speed and unevenness of each measurement point should be recorded.

What should I do if the wind speed is uneven when multiple fans are configured?

It is recommended to confirm whether the rotation speed of each fan is consistent, whether the arrangement spacing is reasonable, and to unify the operating status through the control system.