Number of views: 7245 Author: Aili Industry Release time: 2027-09-20 Source: Ai Li Industrial
How to check the change in room pressure difference after replacing ULPA? Return air and pressure control
If the room pressure difference changes after the ULPA filter is replaced, the air supply, return air, exhaust and pressure control should be checked at the same time. The difference in resistance between the old and new filter elements may change the air volume, but the room pressure difference is not a direct reading of the filter element resistance. If the pressure difference changes after replacing the filter element, you would intuitively think that it is caused by the different resistance of the new filter element. However, the pressure difference is the result of the balance between the supply air volume, the return air volume and the exhaust air volume. The filter element resistance is only one of the factors that affects the air supply volume. Fan speed adjustment, damper position, exhaust volume changes, and pressure difference sensor status may all cause the pressure difference to change. Aili Industry isFFU fan filter unit andIn the matching of the fan filter unit at the EFU equipment end , the air supply volume, return air conditions and pressure control are checked in the same plan.The FFU computer group control system records the partition air volume, pressure difference and operating parameters before and after replacement. When the pressure difference changes, the source can be determined by comparing the data.
1. Record the status before and after replacement: comparison under the same operating mode
Compare the return and exhaust air under the same production mode, door status and control settings to check whether the pre-filter has been replaced or the fan has been adjusted at the same time.
If the operating mode is different, the door opening and closing status is different, and the control settings are adjusted before and after replacement, the pressure difference data cannot be directly compared. The recording should indicate the operating mode, door status, fan speed setting and damper position at the time of replacement to ensure that the before and after data are compared under the same conditions. Aili Industry isThe HEPA/ULPA filter replacement plan provides comparative data based on the original system operating conditions.The FFU computer group control system records the operating parameters before and after replacement. If the pre-filter is replaced or the fan is adjusted at the same time, the changes will be marked separately. The relationship between levels and filtering requirements can be found inISO cleanliness level comparison。
2. Distinguish between filter element and control factors: pressure difference is not a direct reading of filter element resistance.
Changes in the pressure loss of the new filter element, fan speed limit, damper action and sensor status may affect the pressure and should be checked according to the link.
When the resistance of the new filter element is lower than that of the old filter element, if the fan speed remains unchanged, the air supply volume will increase and the positive pressure in the room may rise; but if it is constant air volume control, the fan will automatically slow down to maintain the air volume, and the pressure difference may not change significantly. Conversely, if the differential pressure sensor itself drifts, the reading changes independent of the filter element. Aili Industry isThe FFU fan filter unit package provides power data according to two states of initial resistance and final resistance.The FFU computer group control system records the fan speed, damper position and sensor status. When the pressure difference changes, press the 'filter element - fan - damper - sensor' link to exclude items one by one. The relationship between pressure difference control and filter element resistance can be referred toHEPA FAQs and Selection Guide。
3. Rebalance and confirm the area: the direction of the pressure difference is more important than the numerical value
After adjustment, check the pressure direction, air volume, uniformity and related cleaning performance, and keep control parameters and maintenance records.
The goal of pressure difference adjustment is to maintain the pressure direction required by the design - the clean area maintains positive pressure to adjacent areas, and special areas may require negative pressure. The value of the pressure difference should be within the design range. If it is too large, it may affect door opening and air flow organization. If it is too small, it may lose protection. Aili Industry isFFU fan filter unit andThe fan filter unit at the EFU equipment end supports zone speed adjustment. After replacement, the air supply volume can be readjusted to bring the pressure difference back to the design range.The FFU computer group control system records the partition parameters and pressure status before and after adjustment. The boundary of pressure difference adjustment can be referred toULPA ultra-high efficiency filter FAQ and selection guide。
4. After core replacement, if the air supply increases but the exhaust air remains unchanged, the room pressure may rise and should be rebalanced according to the project goals.
After core replacement, if the air supply increases but the exhaust air remains unchanged, the room pressure may rise. It should be rebalanced according to the project goals rather than assuming that higher is better. Excessive positive pressure will cause difficulty in opening the door, airflow overflow, and even affect the pressure gradient in adjacent areas.
Aili Industry isIn the non-standard ULPA filter replacement project, the balance plan after replacement is evaluated based on the air supply and exhaust relationship of the original system.The speed adjustment capability of the FFU fan filter unit can be reset after the air supply volume changes.The FFU computer group control system records the pressure status of each area to facilitate rebalancing according to the design gradient. For requirements on pressure control at the equipment end, please refer toEFU FAQ and technical support。
5. Related questions and answers
Will the greater the room pressure difference, the better the protection against pollution?
It needs to meet the project design scope. Excessive pressure difference may affect the door and air flow. You cannot just pursue a larger value.
Is the change in pressure difference after replacing the element necessarily a problem with the filter element?
uncertain. Fan speed regulation, damper position, changes in exhaust air volume and sensor status may affect the pressure difference and should be investigated by link.
Do I need to rebalance the system after replacing the filter?
Usually required. The resistance of the new filter element is different from that of the old filter element, and the air supply volume will change. The air supply and exhaust balance should be re-confirmed according to the design requirements.
6. Related articles
ULPA ultra-high efficiency filter FAQ and selection guide
FFU computer group control system
7. Key points for selection and acceptance inspection
Check items |
Check the key points |
|---|---|
Comparison before and after replacement |
Operation mode, door status and control settings are consistent |
Filter element factors |
Difference in resistance between old and new filter elements and changes in air supply volume |
control factors |
Fan speed, damper position and sensor status |
pressure direction |
Positive or negative pressure gradient required by design |
rebalance |
Confirmation of the area after adjustment of supply and exhaust air |
8. Product matching and technical support from Aili Industrial
Aili Industry isFFU fan filter unit andIn the matching of the fan filter unit at the EFU equipment end , the air supply volume, return air conditions and pressure control are checked in the same plan.The FFU computer group control system records the partition air volume, pressure difference, rotation speed and sensor status before and after replacement. When the pressure difference changes, the source can be determined by comparing the data.The HEPA/ULPA filter replacement program provides comparative data based on the original system operating conditions.The FFU fan filter unit supports zone speed adjustment. After replacement, the air supply volume can be readjusted to bring the pressure difference back to the design range;The non-standard ULPA filter replacement project evaluates the balanced plan based on the air supply and exhaust relationship of the original system.The FFU computer group control system records the pressure status of each area to facilitate rebalancing according to the design gradient. 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.
