Which parameters of filter materials should be checked first in high-humidity environments?
For high-humidity environments, choose HEPA. A common approach is to ask for a humidity range. However, the impact of moisture on the filter cannot be explained clearly by a single parameter.
Filter media, edge sealants, gaskets and frames all respond differently to humidity. When selecting, check each item, rather than just confirming whether the filter material is 'moisture-resistant'.
First distinguish between high humidity and direct contact with water
The two situations have different filter requirements.
The relative humidity of the air is high, and the filter material is soaked by condensed water or cleaning water, which are two working conditions. The former mainly affects the hygroscopic performance and long-term stability of the material, while the latter may directly change the structure and sealing state of the filter material.
Before selecting, find out the source of moisture, operating temperature and whether there is a risk of condensation after shutdown. Only by providing this information to the supplier can the specific scope of application of the material be confirmed, rather than discussing the moisture resistance level in general.
The hygroscopic properties of the filter material itself
Different filter materials react differently in the face of humidity.
After the glass fiber filter material absorbs moisture, the fiber structure and filtration performance may change. PTFE filter material has relatively low hygroscopicity and may have better dimensional stability in high-humidity environments. For comparison of these two types of materials, please refer to the relevant instructions for glass fiber and PTFE filter material selection.
When checking, you should ask: under the target temperature and humidity conditions, what is the changing trend of the resistance of the filter material, whether the strength is affected, and whether there is a recommended upper limit of humidity. These data should come from the supplier's material data rather than general empirical values.
Edge banding glue and gasket cannot be ignored
Several parts other than the filter material also need to be checked in high-humidity environments.
Edge sealing glue : The glue line between the filter material and the frame may age or reduce the bonding strength if it is exposed to high humidity environment for a long time. This type of problem will not appear immediately, and may cause leaks after running for a period of time. When selecting, confirm the suitability of the adhesive material at the target humidity.
Sealing gasket : The resilience performance may change after moisture absorption, which affects the sealing effect after compression. When replacing the filter element, if the sealing gasket has been used for a long time, it is recommended to evaluate whether it needs to be replaced.
Outer frame : Whether the anti-rust treatment of the metal outer frame meets the humidity requirements. If the outer frame rusts or deforms in a high-humidity environment, the contact state of the sealing surface will be affected. involving For HEPA/ULPA air filter products of different grades, these material requirements may be different. When checking, follow the corresponding product information.
Incorporate resistance changes into monitoring
Dampness of the filter material may cause abnormal resistance. Drainage, pre-filtration and fan operation also need to be checked on-site.
If the filter is in a high-humidity environment for a long time, the resistance change trend is different from that in a dry environment. It is recommended to consider front-stage dehumidification and drainage measures simultaneously during system design, and record pressure difference changes during operation. For matching FFU fan filter unit system, changes in filter material resistance will affect the fan operating point, and monitoring data can help determine whether adjustments are needed. Device-side applications such as The EFU equipment-end fan filter unit has a compact internal space. If the equipment itself has the risk of condensation, the installation location and protection method of the filter element need to be considered together.
What to do when moisture occurs
After contact with condensed water or cleaning water occurs, isolate the source of pollution first and record the water damage range and pressure difference changes.
If the filter element is dry on the outside, it does not mean that there is no problem with the internal pleats and glue lines. It is necessary to decide whether to re-inspect or replace according to the supplier's instructions and project leak detection requirements. Do not continue to use it just because the appearance returns to normal. If there are water stains, deformation or sudden change in pressure difference on the appearance, the handling should be more cautious.
It is recommended to record the initial air volume and pressure difference during operation as a basis for comparison after a damp event. For the location of the sealing structure, it is recommended to re-inspect according to the project requirements after getting wet to confirm whether the sealing status is affected.
About Aili Industrial’s high-humidity working condition cooperation
Aili Industrial can discuss filter material configuration based on filtration level, air volume, resistance and equipment operating conditions. filter with FFU fan filter unit、The fan filter unit at the EFU equipment end is matched in the same manufacturing system, and the filter material, edge sealing material and complete machine structure can be confirmed together during the planning stage.
For projects in high-humidity environments, it is recommended to provide the continuous temperature and humidity range, temperature fluctuation range, whether there is a risk of condensation or water splashing, as well as the installation location and operating time. Material selection and specific performance should be subject to confirmed product technical data.
