How often should HEPA filters be replaced?

This question is often asked in the procurement and operation and maintenance links: How often should HEPA be replaced?

Straight answer: There is no fixed replacement year for HEPA that applies to all projects. The operating pressure difference, air volume, cleanliness monitoring, leak detection results and on-site pollution load should be combined to determine whether replacement is needed according to project maintenance requirements.

Taking 'how often to replace' as a fixed number can easily lead to two deviations: replacing it before it reaches the end of its life, causing waste; or waiting for the planned cycle after abnormalities have occurred, affecting the clean environment.

Step 1: Establish an operating baseline for the new filter element

After installing and leveling the system, record the actual air volume, initial differential pressure, and filter number.

Subsequent comparisons should be conducted under the same fan gear and operating conditions as much as possible to avoid misjudgment of dust accumulation speed due to changes in air volume. For matching For the filter used in the FFU fan filter unit , it is recommended to record the unit gear and single table wind speed at the same time as the starting point for subsequent judgment.

Step 2: Separate performance changes from abnormal events

A gradual increase in the pressure difference can indicate dust accumulation. A sudden drop in the pressure difference requires checking the measuring point, fan status and bypass air leakage.

Damage to the filter material or failed on-site leak detection may also trigger treatment when the predetermined final resistance is not reached. Accumulated trends and sudden anomalies are two types of signals with different properties , and they are processed in different ways. To troubleshoot exceptions during operation, please refer to HEPA on-site leak detection related recording method, the leak point location and number are stored correspondingly.

Step 3: Form a closed loop after replacement

When replacing, check the installation frame and seals, record the reason for the old filter element and the model of the new filter element; after the operation is stable, re-measure the air volume, pressure difference and leak detection required by the project.

Aili Industrial can provide spare parts selection support in combination with filters and air supply equipment. For device-side applications, such as After replacing the filter element inside the fan filter unit of the EFU equipment , you should also check whether the wind speed in the actual operating gear of the equipment has returned to the target range.

Step 4: Examples of replacement timing

If the pressure difference of a certain filter element is stable after two years of operation and the leakage test is qualified, it cannot be judged by its age alone and must be replaced; if another filter element has been used for a shorter period but is damaged or has leaks, it cannot wait until the planned period to deal with it.

In both cases decisions will be made based on the risk and maintenance requirements of the project. For occasions such as semiconductors and pharmaceuticals that have high requirements for particle control, the judgment is usually based on leak detection results and operating data rather than the operating time itself.

quick checklist

Application background and judgment boundaries

Maintenance plans should be developed according to the installation location, pollution load and operation mode. The air volume and pressure difference after the new filter element is installed will be the benchmark for future comparisons; if the fan speed or front-stage filtration method is changed midway, it should be marked in the ledger to avoid misjudgment of service life.

For adopting In areas where HEPA/ULPA air filters are configured at different levels, it is recommended to establish separate accounts by level and location. It is not appropriate to cover all filters in the same cycle. Regarding the position of the sealing structure of the liquid tank, you need to check the status of the blade edge and tank body when replacing it. Please refer to liquid tank seal HEPA . Interface description of

About Aili Industrial’s spare parts selection support

Aili Industrial can provide spare parts selection support based on the original HEPA model, installation interface and operating parameters. Keeping historical records of air volume and pressure difference can make the replacement plan more consistent with actual working conditions.

Aili Industrial produces HEPA/ULPA filters and supporting FFU fan filter unit , EFU and high-efficiency air supply outlet. When filters and air supply equipment are matched in the same system, spare parts specifications and interfaces can be uniformly checked at the ordering stage to reduce adaptation problems during replacement. For adopting It is recommended that the location of the ULPA ultra-high efficiency filter be marked separately in the ledger so that leak detection and replacement can be arranged according to corresponding requirements.