When FFU has multiple working modes, how should the filter be selected?
Direct answer: The filter should first be selected according to the cleanliness and particle control requirements of the process, and then check whether the FFU can provide the required air volume at each planned working gear. The high speed gear needs to check the filter resistance and fan capacity; the low speed gear needs to verify the actual air supply and airflow distribution. Just because energy saving or standby modes are set, the filtration requirements required in production areas cannot be reduced.
Clean room and equipment-side FFU may adopt fixed operation, step-by-step speed regulation or zone group control. Filter loadingAfter the FFU fan filter unit , its efficiency, resistance, sealing and size will affect the performance of the entire machine. When selecting a filter, you need to confirm these conditions together with the project's working mode.
First determine the filtration efficiency according to the most stringent actual process requirements
The cleanliness goals of each area, the particles that need to be controlled, and the filter testing requirements should be clearly defined, and then the correspondingHEPA or ULPA air filter . The working gear can be adjusted according to the operating status allowed by the project, but the filter itself should meet the actual process requirements of the area.
If a piece of equipment has only local high-cleaning requirements, the equipment end and room air supply plans should be checked separately to avoid applying the same filtration requirements to all FFUs.
Compare filter resistance at common gears
Filter resistance should be compared under the conditions indicating the test air volume. After determining the filter, you should check whether the fan can overcome the resistance of the filter and related systems when the FFU reaches the target air volume at the production speed. If you useFor ULPA filters , the fan operating point, power consumption and overall air volume should be rechecked.
Low gear also needs to be verified. After lowering the fan speed, the filter is still working, but the regional air supply volume and airflow distribution will change; passing the filtration efficiency does not mean that the clean environment in low-speed mode will necessarily meet the standard.
Consider the change in resistance after filter operation
The initial resistance of a new filter is only one of the selection criteria. If the resistance changes after operation, the actual air volume at the fixed gear may decrease; if the air volume needs to be maintained, the operating gear and power consumption may increase. The project should agree on pressure difference monitoring, air volume review and replacement conditions to avoid a certain mode losing its original air supply capacity during long-term operation.
When multiple FFU partitions are running, the filter configuration and control settings of each partition should also be recorded. Prototypes and field tests should cover the main working modes planned to be used, and indicate the filter model, status, FFU gear and measurement method.
Sealing and maintenance conditions must also be confirmed simultaneously
The filter frame, sealing method, installation size and replacement direction should match the FFU box and on-site maintenance space. After replacing the filter, check the installation status according to project requirements and review the air volume of the whole machine in the corresponding mode. It cannot be judged based on the filter efficiency report alone that the FFU after replacement still meets the original performance requirements.
Aili Industrial can match filters, fans, motors and control solutions based on process cleanliness requirements, operating modes, target air volumes and installation conditions. For batch projects, it is recommended to first verify each working gear through a prototype, and then write the filter configuration, test conditions and maintenance requirements into the technical agreement. Specific performance is subject to test results under agreed working conditions.
Q: Can FFU low-speed mode use a less efficient filter?
Answer: Filter efficiency should be determined according to regional process requirements. Whether the low-speed mode is available should be verified by the air volume and cleanliness in this mode.
Q: Is it okay to only test the matching of the filter and FFU at the highest setting?
Answer: If the project also plans to use other gears, the actual air supply performance of these gears should be checked separately.
Q: Will the filter pressure difference be the same after switching the working mode?
Answer: Not necessarily. Changes in air volume will affect the measured pressure difference, and the corresponding operating gear should be noted when recording and comparing data.
