How to determine the ULPA leak detection method and threshold? Standards and Project Requirements

The ULPA filter leak detection method and threshold should be determined by the filtration level, detection object, applicable standards and project requirements. Universal numbers from a certain HEPA method cannot be directly applied to all ULPA projects. If the leak detection threshold is set too wide, leaks may be missed; if it is set too narrow, instrument background and statistical fluctuations will cause the results to lose resolving power. Whether the threshold is reasonable depends on whether the method and instrument can support this judgment level. At the manufacturing end, Aili Industries has a systematic management method for leak detection parameters of different levels and different detection objects. It can match the corresponding leak detection methods and threshold recommendations according to the standards adopted by the project and the detection objects, instead of assigning the same number to all projects.

1. Clear judgment objects: Factory leak detection of the filter element and leak detection of the installation system are two different things.

The boundaries of the local leak detection of the filter element at the factory and the leak detection of the installation system are different, and they should be written clearly respectively. Global efficiency limits also do not automatically serve as local scan thresholds.

The factory leak test verifies the status of the filter element body on a standard bench, while the installation system leak test verifies the integrity of the filter element and the sealing interface after it is installed in the box. The detection objects, scanning ranges and judgment objects of the two are different, and the thresholds may also be different. Aili Industry isWhen HEPA/ULPA filters are delivered, the factory leak detection report and the on-site installation leak detection requirements are distinguished.The leak detection object and scanning range are clearly marked in the ULPA ultra-high-efficiency filter report, and the project party can perform the same object range when conducting on-site leak detection. The relationship between levels and filtering requirements can be found inISO cleanliness level comparison。

2. Confirm the detection capability of the method: the instrument, aerosol and sampling conditions must support the threshold value

The instrument, aerosol, concentration and sampling conditions should be suitable for the required determination level to avoid insufficient sensitivity or background conditions to give a definite conclusion.

The rationality of the threshold is based on the detection capability of the method. If the judgment level is lower than the minimum detection limit of the instrument, or the background fluctuation is greater than the threshold, the test results cannot distinguish between real leaks and background noise. Aili Industry isThe ULPA ultra-high-efficiency filter testing process will confirm aerosol generation, upstream concentration stability and instrument status to ensure that the testing conditions can support the judgment level used; if the project proposes lower threshold requirements, it can first evaluate whether the instrument and background capabilities are met, and then determine the testing plan. For leak detection background control methods, please refer toHEPA FAQs and Selection Guide。

3. Unify rules before testing: exception confirmation, allowed processing and retest scope should be agreed upon in advance

Agree on exception confirmation, allowed processing, retesting and reporting scope. The requirements in the contract or technical agreement should be consistent with the approach adopted.

When an abnormal signal occurs during the leak detection process, how to confirm it, whether it can be repaired, and what range should be retested after repairing. If these rules are not agreed upon before the test, disagreements may easily arise during the test. Aili Industry isIn the non-standard ULPA filter project, the abnormality confirmation method and retest scope can be specified according to the project agreement. The test report records the abnormal location, processing method and retest results to ensure that the conclusion corresponds to the final status. For the cooperation between sealing treatment and leak detection, please refer toULPA ultra-high efficiency filter FAQ and selection guide。

4. When the project requirements are higher than the general standards, first check the achievability before committing.

Some projects will put forward more stringent leak detection requirements in addition to the general standards. In this case, you should first check the achievability of the detection method under the judgment level, and then confirm whether it can meet the requirements.

Aili Industry isWhen the ULPA ultra-high-efficiency filter project encounters leak detection requirements that are higher than the general standard, the feasibility will be evaluated from three aspects: instrument capability, aerosol conditions and background control, and the corresponding detection plan and judgment basis will be given, instead of directly accepting an unverifiable number. Please refer to the conditions for installing leak detection on the equipment side.the fan filter unit on the EFU equipment side .Instructions related to

5. Related questions and answers

Is the lower the threshold, the more professional it is?
The threshold needs to have applicable basis and achievable detection capabilities, and any stricter number cannot be used to replace the correct method.

The filter element passes the factory leak test. Do I still need to check for leaks after installation?
need. The factory leak test verifies the filter element body. After installation, the box and sealing interface are added. Leak test in the installed state should be performed according to project requirements.

The project requirements are more stringent than the standards. Can we just follow the project requirements?
The feasibility of the detection method at this judgment level should be evaluated first, and then the test plan and judgment basis should be confirmed.

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7. Key points for selection and acceptance inspection

8. Product matching and technical support from Aili Industrial

At the manufacturing end, Aili Industries has a systematic management method for leak detection parameters of different levels and different detection objects. Leak detection methods and threshold recommendations can be matched according to the standards and detection objects adopted by the project.When HEPA/ULPA filters are delivered, the factory leak detection report and the on-site installation leak detection requirements are distinguished.The ULPA ultra-high-efficiency filter report indicates the leak detection object and scanning range. The detection process has confirmation steps for aerosol generation, upstream concentration stability and instrument status.The non-standard ULPA filter project can specify the abnormality confirmation method and retest scope according to the agreement. When encountering leak detection requirements higher than the general standard, the feasibility will be evaluated from three aspects: instrument capability, aerosol conditions and background control. Provide process objectives, installation drawings, operating conditions and acceptance requirements, and can further communicate ULPA standard specifications, non-standard interfaces, samples and batch matching. The specific parameters and test range are based on the confirmed model and technical documents.