How to confirm if the chemical filter airflow arrow is not clear?

When the chemical filter arrives, the airflow arrows on the outer frame are worn, covered, or not clearly marked in the first place. How to confirm the installation direction at this time?

Direct answer: Don’t guess based on experience, and don’t directly apply the direction of the old filter element. You should refer to the product information and installation instructions of the model, or confirm with the supplier. If there is directional information on the packaging or label, check that too. Install after confirmation to avoid rework after installation.

Check product identity first

When the direction is unclear, the first step is to confirm what model and configuration the filter is.

model and batch. Record the model, batch or serial number on the filter element to facilitate querying the supplier for the installation instructions of this model. Different models may have different airflow direction requirements, and different batches of the same model generally do not change the direction definition.

Media category. Is it the medium used for acidic gas, alkaline gas or organic vapor? The filter layer structure of different media may be different, and the air flow direction may also have specific requirements. Please refer to the specific classification Discussion on why chemical filters should be selected according to the target gas .

Composite structure. If it is a multi-layer composite filter material, the functions of the front and rear layers may be different. For example, a layer of pre-filtration, a layer of chemical adsorption, and a layer of protection. This structure has clear requirements for the order of air flow, and reversing the direction may affect the treatment effect. For specific differences, please refer to Discussion of whether chemical filters can handle both particulate matter and gases .

There are installation instructions in the product documentation. Regular products will come with installation instructions or have directions marked on the packaging. If the data is lost, you can view it Chemical filter product series page, or contact the supplier to obtain instructions for the corresponding model.

Distinguish direction and sealing interface

When confirming the direction, you should also look at the sealing interface clearly.

Arrows indicate the direction of air flow. Air enters from the starting point of the arrow and exits in the direction the arrow points. If the structures on both sides of the filter element are different, such as a protective net on one side and a sealing gasket on the other, the direction may correspond to these features.

Gasket location also provides clues. The gasket or tank is usually located on the side that needs to fit into the mounting frame. If the sealing surface of the installation frame is on the air inlet side, the sealing gasket of the filter element should also be on the corresponding side. Checking the direction arrow and the sealing position together can improve the accuracy of the confirmation.

You cannot judge based on the color of the filter material or the appearance of the front and back. Some products look similar on both sides but have different internal structures or media configurations. Guessing the direction based on appearance is risky. For specific installation inspection, please refer to Discussion of what appearance and labels to check before installing a chemical filter .

The direction of the old filter element can only be used as a reference and cannot be copied. If the old filter element and the new model are not the same product, the orientation requirements may be different. Even if it is the same model, the old filter element may be installed backwards. Subject to product information.

Keep records after confirmation

After confirming the direction, it is recommended to record the information to facilitate subsequent maintenance.

Record content: model, batch, installation location, actual installation direction, confirmation basis (data, supplier’s reply or drawings). If the supplier provides a written explanation, file it as well.

Take photos to keep. The photos before and after installation can help you quickly confirm the direction when replacing it next time. When the internal space of the equipment is tight, it is easy to get confused when replacing the filter element. Having photos will save a lot of trouble.

Simultaneous verification of seals. After the direction is confirmed, check the frame bypass according to project requirements during installation. For specific methods, please refer to Discussion on how to check frame bypass after chemical filter installation .

When it comes to device-side applications, include direction information in maintenance records. Supporting FFU with chemical filter or For systems with MAU box-type chemical filters , it is recommended that directional information be included in the maintenance records.

Project judgment example

In a project, the chemical filter was replaced. The airflow arrow on the old filter element was worn and could not be seen clearly. The operator directly installs the new filter element according to the installation position of the old filter element.

After operation, it was found that the outlet concentration at this location did not drop significantly. The investigation confirmed that the internal structure of the new filter element is different from the old model, and the air flow direction is required to be opposite. After reinstalling according to the product instructions for the new model, the outlet concentration returned to normal.

This case illustrates: When the direction is unclear, the product information of the current model should be used as the standard, and the judgment should not be based on old experience. involving When selecting a chemical filter product series , it is recommended that the installation direction requirements be written into technical documents and on-site records.

Key points for selection and acceptance inspection

About Aili Industrial’s direction sign package

Aili Industrial has independent manufacturing capabilities in filters, motors, fans, control systems and sheet metal processing, and can provide chemical filter product series and supporting air supply equipment. The product can be marked with air flow direction and installation instructions according to project requirements, and the direction requirements of the corresponding model will also be indicated in the accompanying information. For products with composite filter layers or special structures, installation direction confirmation information can be provided upon delivery.

Related products:Chemical filter product series、MAU box chemical filter、FFU comes with chemical filter . The specific technical documents and test results confirmed by the project shall prevail.