How to distinguish filter material leaks and seal leaks during on-site leak detection?

When abnormal readings appear during on-site leak detection, many people's first reaction is 'the filter element is broken.' However, in actual inspection, the leakage point may come from the filter material itself, or it may come from the edge sealing, sealing gasket or installation frame. The two types of problems have different treatment directions. Distinguishing them first and then taking action can reduce unnecessary replacement and rework.

You can first make a preliminary judgment based on the location of abnormal readings: if there are abnormalities inside the filter surface, focus on checking the filter material or pleats, and if there are abnormalities along the four sides and corners, focus on checking the edge sealing, sealing gasket and installation frame. But ultimately it still needs to be combined with repeated scanning and on-site structural confirmation.

Step 1: Record the leakage point distribution

Mark the leakage point on the filter element number and location diagram, and record whether it is near the filter material, glue filling line or installation interface.

Abnormalities appear along the continuous edge, which is different from the investigation direction of a single filter paper pinhole. Location information is more important than 'whether there is a leak' - it is the first-hand basis for distinguishing the two types of leaks later.

For installation in FFU fan filter unit or The relative positions of the filter, box and filter element on the fan filter unit at the EFU equipment end also need to be marked on the same picture to facilitate the determination of which side the abnormal point falls on.

Step 2: Gradually eliminate bypass paths

Check whether the pressing parts are loose, whether the gasket is displaced, and whether the frame is deformed.

If the abnormality disappears after adjusting the interface, the processing and re-inspection results should be recorded accordingly; do not repair the filter paper without positioning it . Once the filter material is processed, the original state of the product is difficult to trace.

Step 3: Control patch boundaries

The treatment method for damaged filter media should comply with the project acceptance requirements and the supplier's permission range.

For leaks that cannot be confirmed, the product can be isolated first and retested to avoid misjudgment of box air leakage as a filter element quality problem. In batch projects, if leakage points appear repeatedly at the same location, the flatness and smoothness of the installation frame should also be checked. the HEPA/ULPA air filter matches. Whether the sealing structure of

Step 4: Interpretation of missing points on four sides

Different investigation steps are usually required for single-point abnormalities in the center of the filter material and continuous abnormalities along a section of the sealing edge.

After scanning and marking the coordinates again, you can check the flatness of the gasket, pressing parts and box body in sequence, and then decide whether to repair the interface or replace the filter element. If the project adopts a liquid tank sealing structure, it is also necessary to check the matching status of the knife edge and the tank body. Please refer to liquid tank seal HEPA . Interface description of

quick checklist

Application background and judgment boundaries

Scanning leak detection focuses on locating local leaks, not just obtaining a 'passed' conclusion. Inspection personnel should record the operating air volume, scanning path, inaccessible locations and each repair situation, so that subsequent maintenance personnel can review the same location.

For use In the case of ULPA ultra-high-efficiency filters , since they are more sensitive to local leakage, the recording requirements for leak point identification are usually more detailed. It is recommended to use the same set of numbering and coordinate labeling methods.

About Aili Industrial’s leak detection cooperation support

Aili Industry can provide high-efficiency filter product information and structural cooperation according to project requirements. The method and criteria for on-site leak detection shall be specified in the project plan, and the filter element number shall correspond to the installation location and processing records.

Aili Industrial produces HEPA/ULPA filters and supporting FFU fan filter unit , EFU and high-efficiency air supply outlet. When the filter and air supply equipment are matched in the same system, the interface size and sealing structure can be uniformly checked before leaving the factory, reducing the difficulty of spotting leaks caused by mismatched interfaces on site.