Why does ULPA need scanning for leak detection?

Direct answer: Because the overall efficiency is qualified, it cannot be proved that there are no local leaks.

ULPA ratings are usually based on overall efficiency. However, for the entire filter or the installed system, air may bypass the filter material, edge sealing, frame or box interface. If there are local leaks at these locations, the overall efficiency test may not be able to accurately locate them. The function of scanning leak detection is to check point by point along the filter material surface, glue seams, borders and interfaces to find out the specific location. When downstream particles exceed the standard and then go back to investigate, the process has often been affected, and the scope of the investigation will be larger.

Overall efficiency and scanning leak detection solve different problems

Overall efficiency describes the comprehensive penetration of a complete product or system under specified conditions. Local anomalies may be averaged out by a large normal area and the readings may appear acceptable. Scanning leak detection does not pursue an average number. It focuses on whether there is a consistently high signal at a certain location.

The two cannot be substituted for each other. Overall efficiency is used for product grading and batch evaluation, and scanning leak detection is used to confirm local integrity after manufacturing and installation. For ULPA, the local judgment is usually more stringent than that of HEPA, and the range, background control and scanning method of the detection instrument also need to match. Specific products can be referred to ULPA ultra-high efficiency filter . Structural description of

Where local defects may come from

Local leaks do not necessarily come from the filter material itself. Common sources include: pinholes or fold damage to the filter material, discontinuous edge sealing glue, peeling of the interface between the glue seam and the frame, gasket displacement, frame deformation, installation bypass, and unsealed box seams or access openings.

Transportation, installation and operation may introduce these defects. Particular attention should be paid to device-side applications.The internal space of the EFU equipment-side fan filter unit is compact, and it is easy to hit the frame or glue seam during installation. Scanning and leak detection is an effective way to confirm the installation status. For specific inspection methods, please refer to the relevant instructions for leak detection at the interface between the filter material and the frame.

The division of labor between factory scanning and on-site scanning is different

The factory scan mainly covers the filter element body: filter material surface, glue seams, and border joints. On-site scanning also covers installation interfaces: filter elements and frames, boxes, access openings and other accessible connection locations.

Factory qualification does not exempt on-site verification. Transportation vibrations, installation operations, and site structures may alter sealing conditions. Supporting The FFU fan filter unit system and the interface between the unit and the ceiling must also be included in the scanning range. The two sets of records, factory and on-site, correspond to different objects and should be confirmed separately during acceptance.

What are the risks of not scanning for leaks?

Failure to deal with local leaks may have several consequences: unstable downstream particle control, failure to find the source of abnormalities, repeated replacement of filter elements without improvement, and increased number of shutdowns for inspections.

Scanning leak detection provides evidence of location. Only by knowing where the leakage point is can we determine whether it is a product problem, installation problem or structural problem. There are also clear targets for rectification and retesting. Without scanned data, troubleshooting can easily turn into extensive guesswork.

Project judgment example

The ULPA that arrived for a certain project had an overall efficiency report from the factory. After on-site installation, no scanning and leak detection were performed, and it was put into operation directly. After a period of time, the downstream particle monitoring is too high.

When troubleshooting, first check the air volume and airflow organization, there are no obvious abnormalities; then check the filter element pressure difference, which is also within the normal range. Later, an on-site scan was performed, and it was found that there was a stable abnormal reading in a corner of the frame, which was a bypass of the installation interface. After treatment and retesting, the particles returned to the normal range.

This case illustrates: overall report compliance and on-site integrity are two different things. Scanning for leak detection may not necessarily solve all problems in advance, but it can narrow the scope of investigation to specific locations. involving Acceptance and scanning requirements for HEPA/ULPA air filters should be clarified during the planning stage.

Selection and Acceptance Checklist

About Aili Industrial’s scanning leak detection package

Whether scanning leak detection can work is related to the product structure, installation interface, and detection plan. The quality of the glue seam and frame is controlled during the manufacturing stage of the product, so the burden of on-site scanning will be much smaller.

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. When the filter is matched with equipment such as FFU and EFU, the interface size and sealing structure can be checked uniformly during the planning stage to reduce local leakage points caused by mismatched interfaces on site. For projects that require scanning and leak detection, product testing data and record cooperation can be provided as agreed.

When enquiring, specify the testing requirements, installation conditions and acceptance methods to help confirm the appropriate configuration and recording scheme. The specific testing methods and judgment standards are subject to the project plan.