How to determine the wind speed on the ULPA target surface? Process requirements and dust risks

The ULPA filter target surface wind speed should be determined based on process protection, contamination migration, equipment layout and operating constraints. If it is too low, the protection may be insufficient. If it is too high, it may also affect materials, noise or energy consumption. The applicable scope needs to be verified. The determination of surface wind speed is not a single numerical choice, but the intersection of three sets of constraints: how fast the wind speed is required for the process to take away the particles, how fast the wind speed the materials and equipment can withstand, and whether the fan and filter can operate stably at this wind speed. Only when the intersection of the three sets of constraints is found can the surface wind speed be based. Aili Industry isFFU fan filter unit andIn the matching of the fan filter unit at the EFU equipment end , the target surface wind speed can be converted into filter area, resistance and fan operating point, so that the wind speed selection can directly correspond to the executable equipment parameters, rather than just a number in the design description.

1. Calculation relationships and units: first write down the formula and caliber clearly

The initial calculated average surface wind speed v=Q÷(3600×A). Among them, Q is the actual air volume (m³/h), and A is the effective air outlet area of ​​the agreed plane (m²). This average value cannot replace the distribution of each measuring point, nor can it be directly used as the wind speed at the process point.

The formula itself is simple, and the caliber is prone to problems. The effective air outlet area is the area of ​​the filter material that actually passes through the airflow, excluding the frame; if the measurement plane is not on the air supply surface but is further downstream, the measured average wind speed will be different from the air supply surface due to jet attenuation. Aili Industry isthe HEPA/ULPA filter technical data respectively.The effective air outlet area and recommended surface wind speed range are marked in The FFU computer group control system can record the actual air volume, and the numerator and denominator have corresponding data when calculating the surface wind speed. The relationship between grade and air supply requirements can be referred toISO cleanliness level comparison。

2. Clear measurement definition: average filter surface speed, local speed and process point speed are not the same thing

Distinguish between the average speed of the filter surface, local speed and process point speed, indicate the measurement distance and measurement point arrangement, and avoid using one position to represent the entire area.

The average speed of the filter surface is the average value measured on a grid near the air supply surface; the local speed is the speed of a specific location; the process point speed is the speed of the location of the protected object. The three values ​​may vary greatly depending on distance and location. Aili Industry isTank seal ULPA filter andThe application instructions for the non-partitioned ULPA ultra-high-efficiency filter give a recommended range based on the average velocity of the filter surface. The project party will perform the verification according to the agreed measurement plane and measurement point layout, and the measurement caliber will be written in advance in the plan. The relationship between face wind speed and resistance can be referred toHEPA FAQs and Selection Guide。

3. Judgment based on actual process: dust, light materials and operating actions must be considered

Taking into account dust, lightweight materials, operating motion and equipment exhaust, air speed targets should serve air path and process stability.

The higher the face wind speed, the better. Excessive wind speed in light material workstations may cause material disturbance. The instantaneous dust generated by operating actions needs to be quickly taken away by airflow but does not require direct strong wind. Equipment exhaust will change the direction of local airflow. Aili Industry isthe EFU equipment end fan filter unit .The air outlet direction and wind speed range can be adjusted according to the equipment structure and process characteristics of The non-standard ULPA filter project can confirm the air supply parameters based on the workstation location and operation mode, so that the wind speed serves process protection rather than simply pursuing numerical values. Please refer to the key points of wind speed configuration at the equipment end.EFU FAQ and technical support。

4. Confirm with the installation results: look at the average value, distribution and flow pattern together

Detect averages, distributions and necessary flow patterns, and verify control settings and ability to maintain after resistance changes. You cannot only use the maximum fan speed as the basis for selection.

The face wind speed calculated during the design stage must be confirmed by actual measurement after installation. The average value reaches the standard but the distribution is uneven, and local protection may still be insufficient; the initial state reaches the standard but the air volume decreases after the resistance increases, and the target may deviate in the later stages of operation. Aili Industry isThe FFU fan filter unit is equipped with EC DC speed adjustment. When the resistance rises, the air volume can be maintained through speed adjustment.The FFU computer group control system records the zone air volume and operating status, making it easy to compare the design surface wind speed with the actual operating data. For installation verification methods, please refer toULPA ultra-high efficiency filter FAQ and selection guide。

5. Related questions and answers

Is the greater the face wind speed, the cleaner it is?
Cleanliness also depends on filtration integrity, pollution load and air flow organization, and cannot be judged solely by speed. High wind speeds may also disturb lightweight materials or increase noise.

If the average wind speed on the filter surface reaches the standard, does the process point definitely reach the standard?
uncertain. The jet will attenuate and change in space, and the speed of the process point needs to be confirmed individually.

How to maintain the target surface wind speed after the resistance increases?
The air volume can be maintained through speed adjustment compensation, or the working point can be rechecked according to the final resistance state. The fan margin should be confirmed in advance when selecting a model.

6. Related articles

ULPA ultra-high efficiency filter FAQ and selection guide

No partition ULPA ultra high efficiency filter

ULPA ultra high efficiency air filter

HEPA FAQs and Selection Guide

7. Key points for selection and acceptance inspection

8. Product matching and technical support from Aili Industrial

Aili Industry isFFU fan filter unit andIn the EFU equipment end fan filter unit , the target surface wind speed can be converted into filter area, resistance and fan operating point, so that the wind speed selection can be mapped to executable equipment parameters;HEPA/ULPA filter technical data respectively indicate the effective air outlet area and recommended surface wind speed range.Tank seal ULPA filter andThe recommended range for the partitionless ULPA ultra-high efficiency filter is based on the average speed of the filter surface.The fan filter unit at the EFU equipment end can adjust the air outlet direction and wind speed range according to the equipment structure and process characteristics.The non-standard ULPA filter project confirms the air supply parameters based on the workstation location and operation method.The FFU computer group control system records partition air volume and operating status to facilitate comparison between design values ​​and actual measured values. Provide process objectives, installation drawings, operating conditions and acceptance requirements for further communicationULPA ultra-high efficiency filters . Standard specifications, non-standard interfaces, samples and batch matching of The specific parameters and test range are based on the confirmed model and technical documents.