When EFU configures U16 filter, the core contradiction is: U16 is a ULPA ultra-high-efficiency filter, and its initial resistance is usually higher than H13/H14 HEPA filter. As the running time increases, the resistance will gradually increase to the final resistance. If the static pressure margin of the fan is insufficient, the actual air volume will attenuate and the face wind speed will decrease, which will ultimately affect the cleaning effect. Therefore, the selection should be carried out in the order of 'target surface wind speed and reverse the total resistance of the system → confirm that the fan can still maintain the target air volume under the final resistance condition → agree on the whole machine performance verification method' instead of selecting the fan first and then installing the filter.

When selecting a U16 filter, the focus is not only on filtration efficiency, but also on whether the entire machine can continue to operate stably under high resistance conditions. The following will start from three levels: filter resistance characteristics, fan matching, and complete machine verification.

1. Resistance characteristics of U16 filter in EFU

U16 is a ULPA-level ultra-high-efficiency filter. According to EN1822 standard, its MPPS efficiency is ≥99.99995%. In EFU applications, U16 filters have the following resistance characteristics:

1. Higher initial resistance : The initial resistance of U16 is usually higher than that of H14 filters of the same size. Common reference values ​​are in the range of 110–150 Pa, depending on the filter material, structure, and surface wind speed;

2. The final resistance increases with the dust capacity : as the operating time increases, the filter resistance gradually increases, and the final resistance can reach 2 times or higher than the initial resistance. For some products, it is recommended that the final resistance be replaced in the range of 500–600 Pa;

3. The influence of face wind speed is significant : ULPA filters are usually designed to operate at a face wind speed of about 0.45 m/s. If the wind speed is too high, the resistance will be significantly increased;

4. Differences in filter materials and structures : Different filter materials and separation methods will affect the resistance characteristics.

For the equipment-side EFU, if the internal space of the equipment is compact and the filter's windward area is limited, the resistance problem of the U16 filter will be more prominent.

2. How to match the fan under high resistance conditions?

The high resistance brought by the U16 filter directly determines that the EFU fan needs to have sufficient static pressure margin. The matching logic is as follows:

Step 1: Determine the target surface wind speed.
According to the requirements of the clean area, confirm the target wind speed of the filter outlet surface, such as 0.45 m/s±20%.

Step 2: Calculate the total system resistance.
The total system resistance = U16 filter final resistance + air inlet local resistance + box internal resistance + air outlet resistance. The final resistance of the filter should be evaluated based on the maximum dust holding state, not the initial resistance.

Step 3: Confirm the fan operating point
. Use the total system resistance as the static pressure requirement for fan selection and confirm that the fan can still output the target air volume under this static pressure. The nominal air volume usually corresponds to zero static pressure or low static pressure conditions and cannot be used directly.

Step 4: Evaluate the speed adjustment margin.
For equipment that requires long-term operation, the fan should retain a certain speed adjustment margin to cope with the increase in filter resistance. When using an EC/DC fan, the control system can automatically increase the speed when resistance increases to maintain a constant air volume.

Step 5: Consider noise and vibration.
Under high resistance conditions, the fan speed is higher, and noise and vibration may increase. For precision equipment such as semiconductor cleaning machines, it is necessary to confirm whether the noise and micro-vibration are within the allowable range.

3. Complete machine performance verification method of U16 filter EFU

The performance verification of the complete machine should be agreed upon during the design stage to avoid deviations due to different methods after delivery. The key points for verification are as follows:

3.1 Verification of face wind speed and air volume

Measure the wind speed at a cross-section 100–300mm away from the filter outlet surface. The number of measuring points can be calculated based on the air supply area, with a minimum of 4 points, and each filter must measure at least 1 point. Record average wind speed and unevenness.

3.2 Filter resistance verification

Measure the filter resistance while detecting the wind speed. The resistance measurement should be carried out under the condition of constant air volume, and the pressure tube probe should be oriented perpendicular to the direction of the air flow to avoid eddy current interference. It is recommended to measure at least 25 times within no less than 2 minutes and take the average value.

3.3 Fan working point verification

Measure air volume, static pressure and electrical parameters, including current, voltage and power, in the complete machine state. For variable frequency or speed-regulated EFU, measurements should be made at different speeds to confirm whether the fan operating point under actual system resistance meets expectations.

3.4 Filter integrity verification

U16 filters should be scanned and tested for leaks one by one in accordance with EN1822 or IEST RP-CC007 standards. Leak detection should be carried out after the assembly of the whole machine is completed to confirm that there is no leakage on the sealing surfaces of the filter and the box.

3.5 Long-term operation verification (optional)

For key equipment applications, verification can be carried out to simulate the final resistance condition: install an adjustable resistance device in front of the filter, simulate the system resistance to the final resistance state, and confirm that the fan can still maintain the target air volume.

4. Parameters required for U16 EFU selection

It is recommended to provide the following information when communicating on the project:

1. Target cleanliness level and particle size requirements;

2. Target surface wind speed or volume;

3. Available filter sizes and mounting options;

4. Available space inside the device, including length, width and height;

5. The system estimates resistance or wind channel information;

6. Power supply, control methods and communication requirements;

7. Whether it needs to be linked with the device master control;

8. Equipment operating conditions, including continuous or intermittent operation, and expected replacement cycles;

9. Acceptance measurement method requirements.

5. Aili Industrial U16 EFU supporting capabilities

Aili Industrial has the following supporting conditions when configuring the EFU with ULPA U16 filters:

• Self-produced filters : HEPA/ULPA filter production capacity, U15/U16 grade available;

• Fan matching : Self-produced EC/DC/AC motors and fans can match the static pressure parameters according to the resistance characteristics of the U16 filter;

• Whole machine verification : conduct air volume, wind speed, resistance 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 ultra-thin or space-constrained devices, please refer toThe structural solution of the 70mm ultra-thin EFU confirms the installability of the U16 filter. For more EFU product systems, please refer toEquipment-side fan filter unit (EFU) andCustom EFU。

FAQ

What is the main difference between U16 filter and H14 filter?

U16 belongs to the ULPA level, and its filtration efficiency for MPPS is ≥99.99995%, which is higher than H14's 99.995%. The initial resistance of U16 is usually higher than that of H14, which requires higher static pressure of the fan.

If the EFU is equipped with a U16 filter, will the fan not be powerful enough?

Depends on fan selection. If the EC/DC fan with sufficient static pressure margin is matched according to U16 final resistance working condition, the target air volume can be maintained. If the model is selected based on the initial resistance, the air volume will decrease in the later stages of operation.

What is the final resistance of U16 filter?

Different products and structures vary greatly. It is commonly recommended that the final resistance be in the range of 500–600 Pa. For some products, the final resistance is recommended to be twice the initial resistance.

Should the air volume of U16 EFU be designed based on initial resistance or final resistance?

The fan working point should be designed according to the final resistance working condition to ensure that the target air volume can still be maintained after the filter resistance increases.

Do U16 filters need to be checked for leaks one by one?

It is recommended to proceed. U16 is an ultra-high-efficiency filter and should be scanned and tested for leaks in accordance with EN1822 or related standards.

What items should be tested for U16 EFU acceptance?

It is recommended to measure the surface wind speed, filter resistance, fan operating point, including air volume, static pressure and power, and confirm the filter leak detection results.

Can the ultra-thin structure of U16 EFU be customized?

Filter thickness and internal diffusion space need to be evaluated. The installability and resistance effects of U16 filters in ultra-thin structures need to be confirmed through prototype testing.