The chemical filter material and its structure may affect the release of downstream particles. Whether it meets the project requirements requires checking the media positioning, powder loss data, filtration sequence and actual air flow. Effective gas treatment is not a substitute for demonstration of particle cleanliness. These two types of indicators answer different questions and cannot replace each other during acceptance.

Particles come from more than just the medium itself

When talking about powder loss from chemical filter media, it is easy to only focus on the medium. In fact, downstream particles may come from multiple links. The release of fine powder from the medium under airflow erosion is one, frame burrs, loose protective nets, gasket wear, edge damage caused by transportation extrusion are two, and dust brought in during the installation process is three. The filter element at the equipment end is small in size and has dense pleats. When the local wind speed is high, the risk of media wear will also increase. When troubleshooting, you should look at the entire filter element and its installation status together, rather than just taking a sample of the media for a powder loss test. For the reason why the device is more sensitive to powder falling off, please refer toWhat equipment-side applications are low dust filter materials suitable for?。

The filtering order determines whether the particles have a second chance to be intercepted.

The sequence of the chemical filter section and the particle filter section directly affects the final particle level downstream. If the chemical filter section is located before the HEPA or ULPA, the particle filter can serve as the second interception, and most of the fine powder released by the media will be intercepted by the rear section; if the chemical filter section is located after the particle filter and close to the protected object, there is no buffer room for media release. The common situation on the equipment side is exactly the latter, so the requirements for low powder drop media and protective network structures are higher. When arranging filter sections, the order should be confirmed based on the air flow path and the location of the protected object, rather than the chemical section being placed at the end by default. Regarding the combination form of chemical first and then particles, please refer toHow does EFEM air inlet chemical filtration correspond to equipment cleanliness requirements?。

Powder loss data depends on test conditions

For the powder loss or gas release data provided by the manufacturer, you need to see clearly what wind speed and installation conditions it was obtained under. The powder loss test of the media sample under low wind speed may be different from the performance of the entire filter element under high surface speed, vibration or start-stop shock conditions. When comparing, you should confirm whether the test object is the media or the finished filter element, whether the wind speed is close to the actual surface speed, and whether the state after transportation and installation is included. In the absence of these conditions, the data can only be used as a qualitative reference.

Combined configurations require separate acceptance

When chemical filtration and particle filtration are used in combination, the two types of effects should be tested separately. It cannot be inferred that the gas standards are met and the particles are also met. If the gas outlet concentration is qualified, it means that the medium is effective for the target component; if the particle count is qualified, it means that the downstream cleanliness meets the requirements. The testing methods of the two are different, and the sampling locations may also be different. After modification or core replacement, it is recommended to arrange gas detection and particle detection separately, and record the sequence of filter sections and wind speed conditions to facilitate subsequent comparison. For basic judgments involving the relationship between filter materials and particles, please refer toCan chemical filters handle oil mist in the air?。

Aili industrial supporting equipment

Will the chemical filter material bring particles to the downstream? Our experience is that the media itself, structural design and installation status each play a part. Looking at the media parameters alone is often not enough. Aili Industry can provide selection packages for box-type, flat-plate and V-type chemical filtration products. For box-type MAU packages, please refer toMAU box type chemical filter , product series can be viewedChemical filter product range . Equipment-side applications can adopt the form of chemical filtration FFU, integrating chemical adsorption layer and HEPA/ULPA particle filtration. The structure of chemical first and then particles allows the fine powder released by the medium to have the opportunity to be intercepted in the later stage. The V-shaped structure provides a larger filtration area in the same box space, helping to reduce surface speed and media erosion. The manufacturing end covers motors, fans, control systems, sheet metal and complete machine assembly. The sequence of filter sections, frame sealing and downstream particle requirements can be confirmed together during the matching stage. Non-standard structures can be adjusted according to equipment space. The specific gas effect, particle performance and replacement cycle still need to be verified based on the corresponding configuration data and on-site working conditions. Actual results are subject to on-site leak detection and particle test results.

Related questions and answers

If particles appear downstream of the chemical filter, is it necessarily caused by powder falling out of the filter material?
uncertain. Frame burrs, loose protective screens, worn seals, and dust introduced during installation can all contribute particles. You should first check the entire filter element and installation status, and then determine whether it is related to the media.

Is it better to place the chemical filter section in front of or behind the HEPA?
When placed in front of the HEPA, the rear section can intercept the fine powder released by the medium; when placed in the back, it is closer to the protected object and has higher requirements for low powder drop. It should be determined based on the air flow path and the location of the protected object.

Can Aili Industrial provide low powder drop combination configuration?
The media and structural form can be checked based on equipment space, wind speed and downstream particle requirements. The chemical filtration FFU can integrate the dual structure of chemical first and then particles. The specific configuration needs to be confirmed based on product information and site conditions.

Related articles

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• How to avoid damaging the sealing edge when installing a chemical filter?

• Can the chemical filter still be installed after the frame is deformed?

• What equipment-side applications are low dust filter materials suitable for?

Key points for selection and acceptance inspection