What to do if the ULPA frame is deformed?

Frame deformation is usually not apparent at first glance. It may appear as a slight deviation in the diagonal line, a slight warping of one edge, or abnormal pressure during installation. A common method on site is to 'press it hard and install it', but this approach often pushes the problem back.

Frame deformation affects not only assembly, but more importantly, the fit of the sealing surface. After the outer frame is deformed, the contact between the sealing gasket or liquid tank and the mounting frame may be uneven. Some places are pressed too tightly, and some places have gaps. In this state, even if the pressing member is screwed in place, the seal may not be reliable. For the specific sealing structure, please refer to the relevant instructions for liquid tank sealing.

Measure first, don’t judge by feel

The first step when discovering possible deformation of the frame is to measure, rather than directly attach the holddowns.

Diagonal measurements. Use a tape measure or laser distance meter to measure the two diagonals of the outer frame. If the lengths of the two diagonals are inconsistent, it means that the outer frame has parallelogram deformation. The amount of deviation should be compared with the tolerance on the product drawing.

Side length measurement. Measure the actual length of the four sides to confirm whether it is consistent with the nominal size. In some cases, side lengths may change due to bending or extrusion.

Flatness check. Place the outer frame on a flat surface and observe whether the four corners are in contact at the same time. If a corner is raised, it means there is deformation at that location. You can also use a feeler gauge to check the gap between the outer frame and the countertop.

Sealing surface inspection. Focus on whether the surface where the sealing gasket or liquid tank is located is flat. If this surface is deformed, even if the overall size deviation of the outer frame is not large, sealing problems may occur.

Record the measurement data and compare it with the tolerance range of the product drawing. If the tolerance is exceeded, the handling method needs to be evaluated. For specific size measurement methods, please refer to the relevant instructions for high-efficiency filter size measurement.

Where the deformation might come from

Tracing the source of the deformation can help determine whether it is a single unit problem or a systemic problem.

Shipping and handling. If a large-sized filter element is squeezed or dropped during transportation, the outer frame may be deformed. During arrival inspection, the outer packaging status and measurement data after unpacking should be recorded. Just because the packaging is intact does not mean that there must be no problems inside. Measurement is the basis. For specific arrival inspection methods, please refer to the relevant instructions for arrival acceptance.

Installation operations. During installation, if one corner is pressed first, if the tool hits the outer frame, or if it is forcibly inserted into the installation frame, deformation may occur. Device-side applications such as The EFU equipment-side fan filter unit has a compact internal space and limited operating space, making it more prone to collision or forced assembly during installation.

Operation stress. System pressure fluctuations, temperature changes, and pressure difference increases after the filter element accumulates dust, which may cause additional loads on the outer frame. If the outer frame is not rigid enough, it may gradually deform after long-term operation.

Improper storage. If the filter elements are stacked improperly, the underlying product will be under excessive pressure and the outer frame may be deformed. When storing spare parts, pay attention to the number of stacking layers and support methods.

Only by looking at the source and measurement results together can we determine whether the problem is an accidental problem or whether it needs improvement in design, installation or storage.

Check sealing and load bearing together

After the frame is deformed, you can't just focus on 'whether it can fit in'.

Sealing surface fit state. Check the contact between the gasket or liquid tank and the mounting frame. If the deformation of the outer frame results in insufficient compression at certain locations, the risk of bypass air leakage will increase. After installation, perform on-site leak detection according to project requirements to confirm the effectiveness of the seal.

Distribution of hold-down parts. Check whether the number and position of hold-down pieces can cover the deformation area. If the deformation is concentrated in a certain corner or a certain edge, and the compaction parts are unevenly distributed, local locations may not be compacted compactly. For specific gasket compression judgment, please refer to the relevant instructions on the gasket compression degree.

Load-bearing structure. If the filter element needs to bear its own weight or system pressure differential load, the deformation of the outer frame will reduce the structural stiffness. Under long-term operation, deformation may continue to develop. During the evaluation, it is necessary to confirm whether the outer frame still has sufficient load-bearing capacity under the design conditions.

Filter media status. The deformation of the outer frame may also affect the stress state of the pleats of the filter material. Check whether the filter material has local indentations or wrinkles due to frame deformation. For specific damage inspection methods, please refer to the relevant instructions on fold deformation.

Processing methods and basis for judgment

The treatment of frame deformation depends on the degree of deformation, location and project acceptance requirements.

Slight deformation without affecting sealing. If the measurement deviation is within the tolerance range, the sealing surface is flat, and the leakage test is qualified after installation, it can continue to be used. However, the measurement data and leak detection results must be noted in the record as a basis for subsequent follow-up.

Local deformations can be corrected. In some cases, slight deformation of the outer frame can be compensated by adjusting the pressing sequence or adding local supports. However, it is necessary to confirm that the seal is still effective after correction, and the gap cannot be covered by forced compression.

Exceeding tolerances or affecting sealing. If the deformation exceeds the product tolerance, or if a sealing problem is found during a leak test after installation, it is recommended to replace the filter element. Forcible use may result in seal failure or damage to the filter material, resulting in higher subsequent treatment costs.

Accompanied by damage to the filter material. If the deformation of the outer frame has caused indentation of the filter material, deformation of pleats, or cracking of the glue seam, it usually needs to be replaced. For specific glue seam inspection methods, please refer to the relevant instructions on glue seam cracking.

Check the mounting frame before replacing. If similar deformation occurs after the new filter element is installed, the problem may lie in the installation frame or the holding structure, not just the filter element itself. Deformation of the installation frame, improper positioning of the pressing parts, or irregular installation methods may repeatedly cause deformation of the filter element. Supporting The FFU fan filter unit system and the internal support structure of the unit must also be inspected.

Re-inspection and verification cannot be omitted

Whether it is continued use or replacement, re-inspection is necessary.

Check for leaks after installation. Scan the filter material surface and surrounding interfaces according to project requirements to confirm the sealing status. The deformation position and surrounding areas are the focus of scanning.

Air volume and differential pressure measurement. Measure air volume and pressure difference under stable operating conditions and compare with design values ​​or historical data. If the air volume is low or the pressure difference is abnormal, it needs to be investigated whether it is related to frame deformation. For specific troubleshooting methods, please refer to the instructions related to insufficient air supply volume.

Record updates. Correspondingly record the measurement data, processing methods, leak detection results and replacement date. If the filter element is replaced, the serial number and initial data of the new filter element must also be included in the ledger. involving Acceptance of HEPA/ULPA air filters , the record content is the same.

Follow trends. If frame deformation occurs repeatedly in similar products, it is recommended to analyze whether there are systemic problems in the installation method, storage conditions or product selection. A single treatment will not resolve recurring failures.

Project judgment example

A batch of ULPA filters arrived for a project. During unpacking and inspection, it was found that the measurement data of two of them were abnormal - the diagonal deviation was about 3 mm, which exceeded the drawing tolerance.

Further inspection revealed that there were collision marks on the outer surfaces of the two units, which may have been squeezed during transportation. The measurements of other products from the same batch are normal.

Treatment method: Isolate and record the deformed products, and contact the supplier to confirm the treatment plan. At the same time, check the installation frame and compression structure to confirm that there are no abnormalities. After replacing the new filter element, the installation leak detection and air volume measurement were normal.

The key to this case is: arrival measurement can detect deformation problems in advance, avoiding the discovery of poor sealing after installation. involving ULPA ultra high efficiency filter or HEPA high-efficiency filters are the same. The acceptance and measurement requirements for

Selection and Acceptance Checklist

About Aili Industrial’s frame quality control

When it comes to frame deformation, the material selection, bending accuracy and welding process in the manufacturing stage determine the initial state, and the operation methods in the installation and use stages determine the subsequent state. If both ends are controlled, there will be fewer problems.

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. The sheet metal processing link can control the dimensional accuracy and structural stiffness of the outer frame according to project requirements, and dimensional inspections are carried out before the product leaves the factory. For projects where frame deformation occurs, measurement data, installation records and on-site photos can be combined to help check the source of deformation and treatment direction. When the filter is matched with equipment such as FFU and EFU, the installation frame interface and supporting structure can also be confirmed together during the planning stage.

Providing measurement data, installation methods and operation records during inquiry or troubleshooting will help confirm the appropriate treatment plan. The specific selection is subject to the technical documents and test results confirmed by the project.