What should I do if the ULPA glue seam cracks and leaks air?

There are usually two ways to discover the cracking of glue seams: one is through on-site leak detection, and the other is abnormal particles appearing in the middle and lower reaches of the operation, which can be traced back to the glue seams after investigation.

No matter which way, after discovery, you can't 'make up for it first'. The reasons for cracking of glue seams are different, and the treatment methods are also different. In some cases, it can be repaired within the allowable range, and in other cases, it means that the filter element can no longer be used. The basis for judgment comes from on-site leak detection results, structural inspection conclusions and project acceptance requirements, and is not based on experience.

Let’s first look at the form of glue joint failure. The glue joint may have local cracking, entire section degumming or interface peeling. Localized cracking usually appears as cracks or voids and can be caused by poor curing, localized stress concentrations, or mechanical damage. The degumming range of the entire section is larger, which is often related to colloid aging, material compatibility or long-term stress. Interface peeling refers to the separation of colloid from the surface of the filter material or outer frame. It may occur on one side of the filter material or on the side of the outer frame. Different forms correspond to different investigation directions. For the specific sealing structure, please refer to the relevant instructions for liquid tank sealing.

First locate the location and cause of cracking

After leak detection finds an abnormality, the first step is to record the location of the abnormality.

Location information should be specific to coordinates or areas. Is it the glue seam on the edge of the filter material, the end of the pleat, the corner of the outer frame, or the location close to the sealing surface. Depending on the location, the reasons may be different.

Check surrounding structures. Is there any frame deformation, filter material damage or sealing gasket displacement near the crack? If the outer frame has been deformed, cracking of the glue joints may be just a symptom, and the fundamental problem lies in the stress on the structure. If the filter material itself is damaged, the interface between the glue seam and the filter material may be affected. For specific damage inspection methods, please refer to the relevant instructions on fold deformation.

Check the running records. Is there any over-temperature, over-humidity, exposure to corrosive gases or system pressure fluctuations? Cracks in glue joints are sometimes the result of operating conditions outside the design range and are not necessarily a problem with the product itself.

Check material compatibility. If the glue seam cracks occur after changing the colloid batch or filter material type, it is necessary to confirm whether the compatibility of the colloid with the filter material and outer frame has changed. For specific material selection methods, please refer to the relevant instructions for sealant selection.

What situations need to be handled with caution

After the glue seam is found to be cracked, it is not recommended to repair it directly and continue to use it in the following situations.

Extensive degumming. If the crack covers the entire edge or corner, simply applying glue may not restore sealing continuity. In this case the filter element structure may have been affected.

accompanied by structural deformation. When the outer frame is distorted, the filter material collapses, or the pleats are severely deformed, cracking of the glue seams is only a superficial phenomenon. If the structural problem is not solved, the repaired glue joints may fail again during operation. involving ULPA ultra high efficiency filter or HEPA high-efficiency filters is the same. The method for judging

Interface peeling occurs repeatedly. If interface peeling occurs multiple times at the same location or on similar products, it indicates that there may be a systemic problem in the material combination or process that cannot be solved by a single repair.

Glue joint cracking is accompanied by particles or abnormal gas release. This situation indicates that cracking has affected the filtration effect or pollution control, and the treatment method needs to be evaluated according to project requirements.

What to do when patching is allowed

If the project acceptance requirements allow repair, and the cracking range is within the allowable range, it can be handled according to the regulations.

The colloid used must be matched. You cannot arbitrarily choose colloid for on-site refilling. The adhesive material needs to be compatible with the original colloid, and the curing conditions and usage environment must also match. Using the wrong colloid can lead to poor bonding or new outgassing problems.

The operation process should be recorded. Record the repair location, extent, colloid used, operation time and environmental conditions. This information will be used in subsequent retesting and traceability.

Complete retest after repair. Re-detect leaks according to project requirements, covering the repair location and surrounding areas. Don't just look at whether the appearance is smooth, you must confirm the sealing continuity according to the testing method.

Preserve patch history. The repair record of each filter element should be kept corresponding to the product number and installation location. During subsequent replacement or troubleshooting, these records can help determine whether the glue joint failure is regular. For specific record requirements, please refer to the relevant instructions for factory inspection.

What should you pay attention to after replacement?

If it is determined that replacement is needed, there are a few things to check before replacement.

Check the mounting frame and seals. Cracks in the glue joints may be related to deformation of the mounting frame, uneven pressing force, or aging of the sealing gasket. If these issues are not addressed, the same failure may recur with new filters.

Review the installation method. During the installation process, is there any uneven force applied to the filter element, or is there any collision with the glue seam position? Device-side applications such as The EFU equipment-side fan filter unit has a compact internal space and is easy to hit the frame or glue seam during installation.

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

A new filter element establishes a new baseline. After replacement, measure the air volume and pressure difference, complete leak detection, and record the initial status of the new filter element. Supporting The FFU fan filter unit system, unit gear and operating mode must also be recorded. For the specific acceptance sequence, please refer to the relevant instructions on whether to adjust the air volume first or check for leaks first.

Project judgment example

During the ULPA on-site leak detection of a certain equipment, it was found that there were continuous abnormal readings at the glue seam position on one side. The investigation found that the crack extended for about one-third of the length along this side, the outer frame had no obvious deformation, and the surface of the filter material was normal.

Check the operating records and there is no history of over-temperature, over-humidity or exposure to chemical media. Checking the installation record, the filter element was installed with tools to adjust its position, and it may have been near the glue seam.

Treatment method: Assess the crack range according to project requirements. The length of the edge crack exceeded the allowable repair range, so it was decided to replace the filter element. The retest after replacement was normal, and the new filter element recorded the initial pressure difference and leak detection results. The failure information of the old filter element is included in the maintenance ledger, and subsequent attention will be paid to whether similar locations reappear.

The key to this case is: to deal with cracked glue joints, you must first determine the scope, cause and structural condition, and then decide whether to repair or replace it. involving The acceptance of HEPA/ULPA air filters has the same judgment logic.

Selection and Acceptance Checklist

About Aili Industrial's glue seam quality control

In the case of glue seam cracking, if the colloid selection, coating control and curing process in the manufacturing stage are in place, the probability of failure during operation will be much lower. The problem is that the quality of the glue seam is not only visible when the product leaves the factory, but also depends on the suitability of the working conditions in long-term operation.

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. During the filter manufacturing process, the colloid coating, curing and inspection links are included in quality control. For projects with glue seam problems, product structure data, operation records and on-site photos can be combined to help check the cause of failure and inspection points. When the filter is matched with equipment such as FFU and EFU, the installation method and interface conditions can also be evaluated together at the planning stage to reduce glue joint damage caused by installation interference.

Providing the failure location, operating conditions and installation records during inquiry or troubleshooting will help confirm the treatment direction. The specific handling method shall be subject to on-site inspection results and project acceptance conditions.