How to design the ULPA one-way flow area? Air supply layout and process protection

The design of the ULPA filter's unidirectional flow area should focus on the process protection range, supply air distribution, return air path and occlusion control. Filter element arrangement rules do not automatically ensure that the protected area forms the expected flow pattern. One-way flow design can easily fall into the 'just fill it up' mentality: if the ceiling is covered with filters and the air volume is full, it is considered that a one-way flow is formed. However, the essence of unidirectional flow is that the airflow direction is consistent, the speed is uniform, and it takes a straight path from the air supply surface to the return air surface. When the filter is full, it only provides the air supply surface. Whether the air flow is really in a straight line depends on the return air position, equipment shielding and process layout. Aili Industrial's product line covers motors, fans, control systems, sheet metal, air filters and complete machine assembly. The unidirectional flow area design can check filtration, power, structure and control in the same plan, instead of selecting and assembling each component separately.

1. Define the area from the workpiece and action: the protection scope is not the entire room

Identify sensitive surfaces, equipment movement, personnel operations and sources of contamination, and determine the spaces and operating conditions that need to be protected.

The protection scope of the unidirectional flow area should be determined by the process. What needs to be protected is the exposed surface of the workpiece, key process points and personnel operating areas, not every corner of the entire room. The boundary of the protection range, the height of the workpiece, the movement trajectory of the equipment, and the position of the personnel operating. This information determines where the air supply surface needs to be covered and where the return air is discharged. Aili Industry isHEPA/ULPA filters andIn the FFU fan filter unit package, confirm the air supply coverage according to the location of the workpiece and the operation mode.For non-standard ULPA filter projects, the air supply surface size and installation direction can be confirmed according to the equipment structure. The relationship between grade and airflow requirements can be found inISO cleanliness level comparison。

2. Coordinate air supply and return air: the air flow needs to be coordinated with the return air to move in a straight line

Check the filter surface layout, air volume distribution, equipment gaps and exhaust air to avoid lateral interference, backflow and personnel located upstream of pollution.

The unidirectional airflow flows vertically downward from the air supply surface, passes through the workpiece, and is discharged from the lower return air. If the return air outlet is deviated, the bottom of the equipment blocks the return air, or the process exhaust changes the local pressure, the airflow will deviate from the vertical direction. The air supply surface and return air surface should be arranged accordingly, and there should be a return air path under the area covered by the supply air. Aili Industry isFFU fan filter unit andWhen supporting the fan filter unit at the EFU equipment end, check the air supply direction according to the equipment layout and return air conditions.The FFU computer group control system records partition air volume and operating status to facilitate comparison of supply air distribution and return air conditions. Please refer to the coordination between supply air and return air.HEPA FAQs and Selection Guide。

3. Equipment shielding and personnel positions must be included in the design: contamination cannot flow from upstream to the workpiece.

When the equipment is located upstream of the workpiece, the particles generated by the equipment will pass through the workpiece with the air flow; when personnel stand upstream of the workpiece, dust generated by the personnel will also be brought to the surface of the workpiece. Unidirectional flow design should consider the position of equipment and people relative to the workpiece, and place the source of pollution downstream of the air flow.

Aili Industry isthe EFU equipment-side fan filter unit, confirm the air outlet direction according to the equipment's action range and the position of the workpiece.When supporting Compact models such as ultra-thin EFU can configure local air supply according to the cavity structure, allowing the air flow to pass through the workpiece and then be discharged. The relationship between equipment layout and air flow direction can be referred toEFU FAQ and technical support。

4. Use actual measurements to verify boundaries: wind speed distribution, flow patterns and particles must be confirmed

Combined with wind speed distribution, applicable air flow visualization and particle confirmation, the layout and operation settings will be retained, and the changes will be evaluated and re-inspected.

The layout and calculation in the design stage are the basis, and the actual effect must be confirmed through testing. Whether the wind speed distribution on the air supply surface is uniform, whether the air flow direction is consistent, and whether the particle concentration at the protective boundary reaches the standard should be tested separately. Tests should cover actual operating conditions, including equipment actions and human operations. Aili Industry isULPA ultra-high efficiency filters can be delivered with clear verification projects.The FFU computer group control system records zone air volume and operating parameters to facilitate comparison of design values ​​with actual measured values. For methods of one-way flow verification, please refer toULPA ultra-high efficiency filter FAQ and selection guide。

5. After adding high-profile equipment to the same workbench, check the downstream obstruction and wake flow.

After adding high-profile equipment to the same workbench, its downstream obstruction and wake should be checked. Do not just confirm that the ULPA is still running in place. Adding new equipment will change the local airflow path, and low-speed areas or vortices may form downstream of tall equipment.

Aili Industry isNon-standard ULPA filters andIn the FFU fan filter unit package, the impact of airflow can be evaluated according to changes in equipment layout, and if necessary, the protective effect can be maintained by adjusting the air supply direction or local strengthening. For the evaluation method after layout change, please refer toHEPA FAQs and Selection Guide。

6. Related questions and answers

Is filling the ULPA ceiling a one-way flow?
The airflow path and distribution should also be checked and verified according to project requirements, and cannot be defined only by the number of equipment.

Does the one-way flow area need to cover the entire room?
uncertain. The scope of protection should be determined by the process, with priority given to key workstations and exposed surfaces of workpieces, and non-critical areas can be configured according to background cleanliness.

What if the device is upstream of the workpiece?
Consideration should be given to relocating the equipment or changing the direction of the airflow so that the source of contamination is downstream of the airflow to prevent particles from passing through the workpiece.

7. Related articles

ULPA ultra-high efficiency filter FAQ and selection guide

FFU computer group control system

Ultra-thin EFU

HEPA FAQs and Selection Guide

8. Key points for selection and acceptance inspection

9. Product matching and technical support from Aili Industrial

Aili Industrial's product lines cover motors, fans, control systems, sheet metal, air filters and complete machine assembly. The unidirectional flow area design can check filtration, power, structure and control in the same solution.HEPA/ULPA filters andThe FFU fan filter unit is equipped to confirm the air supply coverage according to the workpiece position and operation mode.For non-standard ULPA filter projects, confirm the air supply surface size and installation direction according to the equipment structure;FFU fan filter unit andThe EFU equipment end fan filter unit is equipped with a fan filter unit. Check the air supply direction according to the equipment layout and return air conditions.The FFU computer group control system records partition air volume and operating status to facilitate comparison of supply and return air.EFU equipment side fan filter unit equipment side matching confirms the air outlet direction according to the equipment action range and workpiece position.Ultra-thin EFU can be configured with local air supply according to the cavity structure;ULPA ultra-high-efficiency filters can be delivered with a clear verification project, and when the layout is changed, the airflow impact can be evaluated according to new conditions. Provide process objectives, installation drawings, operating conditions and acceptance requirements, and can further communicate ULPA standard specifications, non-standard interfaces, samples and batch matching. The specific parameters and test range are based on the confirmed model and technical documents.