Can ULPA clean or purge?

Direct answer: It is not recommended to wash, brush or blow with compressed air for conventional ULPA finished products.

This is not conservative, but is determined by the structure of this type of product. The filter material of ULPA has a folded structure, which is edge-sealed by colloid and supported by the outer frame. Washing, brushing and high-pressure purging may change the state of these things. Just because the appearance seems to be restored, does not mean that the performance has also been restored.

Whether there is a maintainable design, please refer to the description of the specific model. Not all ULPA cannot be cleaned, but the judgment of 'can be cleaned' should be supported by product data rather than based on on-site experience.

First determine the nature of the dust

Before discussing whether it can be cleaned up, let’s first look at what is accumulated.

Dry dust : It is relatively easy to deal with, but it does not mean that it can be blown away casually. After the dust is blown up, it may enter downstream, or it may settle again in other locations.

Viscous deposition : a film formed by oil mist and solvent residue, adsorbed on the surface of the filter material. This kind of deposit cannot be removed by purging, and water washing may damage the filter material.

Moisture and caking : After moisture enters the filter material, the dust may agglomerate, changing the breathability of the filter material. The performance changes in this case cannot be solved by cleaning.

The color of the filter surface or the dust on the surface cannot be used alone as a basis for judgment. It should be looked at together with the pressure difference, air volume and integrity results. For specific troubleshooting ideas, please refer to the relevant instructions on increased pressure difference.

Risks of purging and washing

Local pressure injury. The concentrated impact force of compressed air may cause the pores of the filter material to expand, pleat deformation or local damage. These injuries are not necessarily visible on the surface.

Liquid intrusion. When water or detergent enters the filter material, it may change the structure of the filter material or remain in the pleats. The appearance will be normal after drying, but the state of the internal glue seams and filter material may have changed.

The glue seam is damaged. The edge sealing glue may soften, crack or degumm under the action of water, solvent or machinery. This kind of problem may not appear immediately during cleaning, but will be exposed after running for a period of time.

Contamination migration. During the cleaning process, particles originally trapped on the filter material may be lifted into the air or pushed to other locations on the filter element. This issue requires even more attention if you are dealing with filters that pose biological or chemical risks.

Therefore, 'air volume recovery after cleaning' cannot be used as a basis for continued use. The recovery of air volume may be due to the filter material being blown through, rather than returning to normal.

Confirmation process when reuse is required

If there is a real need for reuse, or the project allows some form of maintenance, the process should be like this:

Check the product description first. Does this model allow cleaning, what method is used, and what tests need to be done after cleaning. If there is no explicit support, it will be treated as a replacement.

Document type of contamination and treatment process. What was accumulated, what method was used, and how long it took to process. These records will be useful for subsequent judgment.

Complete required retests. After cleaning, don’t just look at the appearance or air volume, but conduct integrity testing according to project requirements. The detection methods and criteria are implemented in accordance with the corresponding standards. For details, please refer to the relevant instructions on filter leak detection.

Damaged parts that cannot be verified should not be installed in critical process locations. If the cleaned state cannot be confirmed by testing, whether to use it in a general position or a critical position needs to be determined according to the project risk assessment.

more reasonable approach

Instead of discussing 'whether it can be washed', it is better to spend time on the source.

The front level protection is in place. If the pre-filtration configuration is reasonable, the load on the terminal ULPA will be small, and the replacement cycle will naturally be lengthened. For specific configuration ideas, please refer to the relevant instructions for pre-filtering configuration.

The pressure difference trend is detected early. By continuously recording changes in pressure difference, replacement can be scheduled before the condition of the filter element deteriorates, instead of waiting until the blockage is severe.

Spare parts management is done in advance. Spare parts are prepared for the filter elements at key locations. There is no need to wait for the goods when replacing them, and there is no need to consider 'whether they can be used.'

Maintenance procedures are clearly written. When the situation is changed, what situation is checked, what situation can be observed first, and written into the maintenance file, so that it is not easy to go astray during execution.

Project judgment example

After a certain filter element was purged, the pressure difference dropped, and it seemed that the condition had improved.

There are two possibilities for this phenomenon: one is that the dust on the surface of the filter material has indeed been blown away, and the resistance decreases; the other is that the filter material itself is damaged or the channel changes, and the airflow takes another path. Both situations may appear as a 'drop in pressure difference' in appearance, but they are completely different in nature.

The differentiation method can only rely on integrity testing. If it passes the test, it can continue to be used; if it fails or cannot be tested, the status of the filter element is uncertain, and whether it should be used or not depends on the project requirements. involving For HEPA/ULPA air filter products of different grades, the testing requirements are implemented in accordance with corresponding standards. Device-side applications such as The replacement of the EFU equipment-end fan filter unit involves equipment shutdown. It is easier to plan spare parts in advance than to deal with them afterwards.

Selection and Acceptance Checklist

About Aili Industrial’s maintenance packages

The prerequisite for cleaning and reusing is to understand the actual status of the filter element. This requires product information, operating data and testing records to make judgments.

Aili Industrial's manufacturing system covers filters, motors, fans, control systems and complete machine assembly, and can provide ULPA ultra-high efficiency filter and supporting air supply equipment. Maintenance requirements will be noted in the product literature, and the filter and When the FFU fan filter unit and EFU are used together, the replacement method and interface conditions can be confirmed together during the planning stage.

When enquiring, specify the operating conditions and expected maintenance methods to help confirm the appropriate configuration and spare parts solution. Specific maintenance requirements are subject to the product description of the corresponding model.