How to decide to replace the ULPA when it is damaged or fails leak detection?

If the leak detection fails, or if damage to the filter material, glue seams, or outer frame is found during disassembly and inspection, the first reaction is often to 'replace' it. This direction is correct in many cases, but 'replace or not' is not the only option, nor should it be decided based solely on a missing point value or service life.

Three questions need to be answered when judging replacement: where is the leak, how large is the range, and whether this location allows continued use. The answers to the three questions are different and they are handled in different ways. Some local defects can be dealt with within a limited range according to regulations, while others must be replaced. For specific leak detection methods, please refer to the relevant instructions for on-site leak detection.

First determine the cause of the leak and the type of defect

Different types of defects have different processing boundaries.

The filter material is partially damaged. Small pinholes, local indentations or slight damage on the filter material surface. If the scope of such defects is small, some projects are allowed to be dealt with according to regulations. However, if the damage involves multiple folds, is large in scope, or is located near the edges of the filter material and glue seams, it usually needs to be replaced.

The glue seam is detached. There is partial peeling between the edge sealing glue and the filter material or outer frame. Small sections of debonding may be treated according to the instructions of the colloid material; when large areas of degumming or accompanied by structural deformation, repair is not recommended.

Install bypass. The leakage point is not on the filter element body, but on the sealing surface between the filter element and the mounting frame. Such problems should be dealt with from the interface and assembly rather than replacing the filter element. Adjusting the compression structure, replacing the gasket or reinstalling can often solve the problem. For specific troubleshooting methods, please refer to the relevant instructions on leak location.

Structural damage. The outer frame is deformed, the folds of the filter material are severely collapsed, and the protective net is damaged. This type of problem involves structural integrity and usually requires replacement. For specific inspection methods, please refer to the relevant instructions on frame deformation.

The key difference is: the leakage point is on the filter element body or the installation interface. There is a problem with the installation interface. Changing the filter element cannot solve the root cause.

Assess leak extent

The size of the range directly affects the processing method.

Small local area. A single point or a very small section is located in the middle of the filter material and does not involve glue seams and borders. In this kind of situation, you can first check whether the project is allowed to be repaired, and then handle it according to the regulations.

Continuous along the edge. Continuous abnormalities along an edge or corner are usually related to glue joints, sealing surfaces or frame fit. It is necessary to locate the specific structural layer first, and then determine whether to repair or replace it.

Distributed in many places. Abnormalities occurring in multiple locations at the same time may indicate that there is a systemic problem with the product, or that the operating conditions are beyond the design range. In this case, a single repair is of little significance, and replacement and cause investigation should be evaluated.

Extensive damage. Damage that exceeds the allowable repair limits, or involves multiple folds or edges, usually requires replacement. Forcible repair may affect filtration efficiency and structural stability. involving The processing of ULPA ultra-high efficiency filter shall be carried out according to the technical documents of the corresponding model.

Check the allowed processing rules of the project

How the project file is written determines the processing boundaries.

Contracts and technical agreements. Is it clearly stated that 'patches are allowed', 'patches are not allowed' or 'patches need to be confirmed by the supplier'. Some projects have specific regulations regarding the scope, frequency, and location of repairs.

Model description. If the product information states the allowed repair methods and scope, follow the instructions. If it is not written, you need to confirm it with the supplier.

The risk level of the application scenario. In key semiconductor processes, pharmaceutical sterile areas, and high cleanliness level occasions, even if the document does not prohibit it, whether the repaired filter element meets the long-term operation requirements still needs to be evaluated. The strength and sealing performance of the repaired location may differ from the original product.

Do not refill the glue yourself without permission. Repairing on-site with ordinary colloid may introduce new outgassing problems, or may lead to poor bonding due to colloid incompatibility. For specific colloid selection methods, please refer to the relevant instructions on selecting sealants according to working conditions.

Consider operational risks

Even if the leakage point is small, it is not recommended to continue using it in some situations.

Critical process locations. Where there are strict requirements for particle control, sealing reliability or contamination control, whether the repaired filter element can meet long-term operation requirements needs to be carefully evaluated. Once it fails again during operation, the impact may extend beyond the filter element itself.

Continuous production occasions. The cost of downtime and replacement may be higher than the filter element itself. If there is still uncertainty after repair, early replacement is more controllable than sudden failure during operation. Supporting FFU fan filter unit or For EFU equipment-end fan filter unit systems, the replacement operation usually involves shutdown arrangements, which should be taken into consideration when making judgments.

Repeated leaks in the same location. If leaks occur multiple times in the same location or in similar products, it indicates that there may be systemic problems in the material combination, installation method, or operating conditions. A single patch will not resolve the root cause and the source needs to be traced.

The replacement cycle is approaching. If the filter element has been running for a long time, even if the leakage point is small, you can evaluate whether to replace it directly based on the remaining life to avoid disassembly and assembly again in the short term.

Closed loop after replacement

After deciding to change, there are still a few things that need to be done simultaneously in operation.

Record the original exception and the reason. The leakage location, range, operating time and working conditions of the old filter element should be recorded. This information can help determine whether the problem is an occasional problem or a systemic one.

Check the installation interface. Check the mounting frame, sealing gasket, and compression structure before replacement. If there is a problem with the interface itself, the same fault may recur when a new filter element is installed.

Re-inspect according to project requirements. After the new filter element is installed, complete on-site leak detection and air volume measurement, and record the initial pressure difference. involving HEPA/ULPA air filters are the same. Acceptance and recording requirements for

Update maintenance ledger. Record the replacement date, new filter element model, serial number, initial data and leak detection results. During the next maintenance, these data will be a reference for judging changes in the status of the filter element.

Project judgment example

During the ULPA leak detection of a certain equipment, a small-scale abnormality was found in the middle of the filter material, with an area of ​​about a few millimeters. The project technical agreement allowed for repairs within a limited range. The operator used matching colloid to treat it according to the procedures. After the retest, the abnormality disappeared, and the retest after three months of operation was still normal.

Another product was found to have major damage on the edge of the filter material, involving two pleats, and there was slight deformation at the corners of the outer frame. This situation was beyond the scope of repair and it was decided to replace the filter element. Before replacement, check the installation frame and compression structure to confirm that there are no abnormalities. The new filter element will pass the retest after it is installed.

This case illustrates: Whether the leaking point can be treated and replaced depends on the defect type, scope and project rules. You cannot simply judge by 'qualified' or 'unqualified'. involving HEPA high-efficiency filter has the same judgment logic. The processing of

Selection and Acceptance Checklist

About Aili Industrial’s replacement judgment package

Behind the replacement decision is actually the judgment of the defect type, impact scope and operational risk. If this judgment is based solely on on-site experience, it is easy to be conservative or radical. If you look at product information, test records and operating conditions together, the direction will be clearer.

Aili Industry has independent manufacturing capabilities in filters, fans, control systems and sheet metal processing, and can provide ULPA ultra high efficiency filter、HEPA high-efficiency filter and supporting air supply equipment. For items with damage or failed leak detection, product structure information, on-site photos and operational data can be combined to help check the type of defect and the direction of treatment. When the filter is matched with equipment such as FFU and EFU, the installation interface and sealing structure can be uniformly confirmed during the planning stage to reduce repeated replacements due to interface problems.

Providing damage information, leak detection records and operating conditions during inquiry or troubleshooting will help confirm the appropriate treatment plan. The specific handling method shall be subject to on-site inspection results and project acceptance conditions.