What is the function of ULPA protective net?

The protective net is a component that often appears on ULPA finished products, but its function is often simplified as 'protecting the filter material'.

This understanding is correct, but not complete enough. The protective net does have a protective function, but its existence also brings several collateral effects: it adds a little resistance, affects the airflow distribution on the air outlet surface, and takes up installation and maintenance space. If you only regard the protective net as an accessory when selecting a model, you may encounter unexpected restrictions during actual installation or leak detection.

Let’s first look at the basic functions of the network. ULPA's filter material has a folded structure, and its surface cannot withstand direct contact or local pressure. During transportation, handling, installation and maintenance, if tools, fingers or other objects accidentally touch the filter surface, it may cause pleat deformation or damage to the filter material. The guard screen forms a mechanical barrier on the outside of the filter material to reduce this type of accidental contact. Some protective nets also serve as structural supports to help maintain the shape of the pleats and prevent channel deformation when airflow passes through. For specific structural features, please refer to the relevant instructions for the structure without partitions.

There are limits to the protective capabilities of the protective net. It is used to reduce accidental touches and light contacts, but does not allow the filter element to withstand arbitrary pressure. If the protective net is used as a load-bearing structure, placing objects on it or relying on the protective net to bear force during installation, the pressure may be transmitted to the filter material through the protective net, causing damage instead. The correct approach during installation and transportation is to support the outer frame rather than pressing the protective screen or filter surface. This should be especially noted in device-side applications.The internal space of the EFU equipment-side fan filter unit is compact, and it is easy to touch the filter surface when disassembling and assembling. The protective net can provide certain protection, but it cannot replace standard operation methods.

The impact of the protective net on the air outlet cannot be judged only by the opening ratio. The opening ratio is a reference index, but the actual airflow distribution also depends on the shape and arrangement of the openings, the distance between the protective screen and the filter material, and whether there is a static pressure box or diffuser structure downstream. For two protective nets with the same opening ratio, if the opening arrangement is different or the distance from the filter material is different, the wind speed distribution on the air outlet surface may be different. The evaluation of the impact of the protective net on the air outlet should be based on the actual measured data of the complete finished product or the complete machine, and cannot be calculated based on the opening ratio alone. Supporting For the FFU fan filter unit system, the wind speed distribution on the outlet surface is related to the internal structure of the unit, and the protective net is only one of the factors. For specific measurement methods, please refer to the relevant instructions for surface wind speed calculation.

The pressure loss of the guard net also needs to be taken into consideration. The protective net itself will add a little resistance, although it is usually not large, but under multi-stage filtration or high air volume conditions, this part of the pressure loss will also be superimposed on the total resistance of the system. If there are strict requirements on air volume or energy consumption during model selection, the pressure loss of the protective net should be within the calculation range. When comparing different products, pay attention to whether the configuration of the protective net is the same, otherwise the difference in resistance may partly come from the protective net rather than the filter material. involving HEPA/ULPA air filter products of different grades are compared in the same way.

Maintenance space is another practical constraint imposed by guard nets. The protective net is set outside the filter material, and the probe needs to be close to the filter surface and frame interface during leak detection scanning. If the distance between the protective screen and the filter material is too small, or the protective screen structure blocks the probe path, the accessibility of the scan may be affected. The protective net must not be set up so that the necessary leak detection areas are inaccessible. This problem should be confirmed during the planning stage, rather than waiting until on-site leak detection only to discover that certain locations cannot be scanned. involving The selection of ULPA ultra-high efficiency filter can be combined with the project leak detection plan to check the protective network configuration. When replacing the filter element, whether the protective net will affect the disassembly and assembly operations should also be considered in the maintenance path planning.

The design of the protective net must also match the working conditions. Material selection, opening size, and fixing methods all need to be determined based on the actual use environment. In corrosive environments, the protective mesh material needs to be corrosion-resistant; under high-temperature conditions, thermal expansion and long-term stability must be considered; in occasions with cleanliness requirements, the surface treatment and particle release characteristics of the protective mesh must also be confirmed. These factors, like the filter material, colloid, and outer frame, are part of the entire product configuration during model selection. For specific material selection methods, please refer to the instructions related to the comparison of glass fiber and PTFE filter materials.

Selection and Acceptance Checklist

About Aili Industrial’s protective network configuration package

The protective net seems to be a small component, but it is related to filter material protection, air outlet distribution, and leak detection accessibility. It is easier to consider these relationships together during the planning stage than to adjust them after installation.

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. For projects with special protection requirements or limited space, the equipment structure, installation method and leak detection plan can be combined to help check the configuration of the protective net. When the filter is matched with equipment such as FFU and EFU, the impact of the protective net on the air outlet distribution and leak detection path can also be evaluated together during the planning stage.

When enquiring, provide the usage environment, installation space and leak detection requirements to help confirm the appropriate network protection solution. Specific specifications are subject to the technical documents and testing data confirmed by the project.