What conditions should be evaluated first before adding a chemical filter to an existing clean room?

The clean room is already in operation, and now it is discovered that gaseous pollution needs to be controlled, and a chemical filtration section is added to the existing system. This kind of renovation project is relatively common, but more complicated than a new construction project - the space has been determined, the equipment has been installed, and production continues.

Direct answer: Before adding a chemical filter, you need to evaluate the sources and targets of contamination, filter location, fan margin, installation space, maintenance conditions and verification methods. You cannot just choose a product based on the size of the existing filter frame and install it, otherwise it is easy to cause excessive resistance, insufficient air volume, or difficulty in maintenance.

Select location from contaminated path

Where the chemical filter section is installed depends on where the contamination comes from.

external input. If fresh air is the main source, consider adding a chemical filtration section to the fresh air unit or air conditioning box. For specific configuration, please refer to Discussion on why MAU needs to configure chemical filtration section .

Internal release. If releases from equipment, materials, or processes within the shop are the primary source, consider handling on a return air or circulation path. For specific configuration, please refer to Discussion of what local contamination FFU plus chemical filter can handle .

Local protection. If only certain workstations or equipment are sensitive to gaseous contamination, localized filtration options can be evaluated rather than treating the entire cleanroom.

First compare fresh air, return air and key areas to avoid installing in paths where gas will not pass. For specific investigation methods, please refer to whether to do air sampling before choosing a chemical filter . Discuss

Check system capabilities

Adding a filter section will change the system resistance, and you need to check whether the fan can withstand it.

Get actual operating data. Record the current air volume, fan gear, and pressure difference in each section of the system. The design parameters may be different from the actual status after many years of operation, and field data should prevail.

Assess new resistance. The initial resistance and final resistance of the chemical filtration section must be included in the calculation of the total resistance of the system. If the original fan margin is insufficient, the fan may need to be adjusted or the system optimized. For specific accounting methods, please refer to Discussion of how much the added resistance of the chemical filter will increase the fan's electricity consumption .

Check air volume distribution. After adding a filter section, the air volume distribution of each branch may change. It is necessary to recheck the branch air valve opening or adjustment method. For specific balancing methods, please refer to whether chemical filtration modification requires re-doing the air volume balance . Discuss

The terminal air volume cannot be lower than the design range. If the clean room has requirements for the number of air changes or air flow organization, the air volume cannot be reduced to affect the cleanliness after adding a filter section.

Check structure and interface

The renovation project is limited by the existing structure, and interface matching is key.

Available space. Is there space to install a chemical filtration section near the existing filtration section? Are the height, depth, and width sufficient? If you don't have enough space, you may need to choose a thin solution or adjust the position. For specific configuration, please refer to Discussion of how to determine configuration when chemical filter thickness is limited .

Install the interface. The outer frame, sealing method, and compression method of the chemical filter section must match the existing frame or box. If the frame does not match, it may be necessary to modify the frame or customize the filter segment. For specific matching methods, please refer to Discussion of how chemical filter sizes match existing filter frames .

Support and weight. The weight of the chemical filter section may be heavier than the original filter section, and it is necessary to confirm whether the ceiling or frame support can bear it.

Maintenance channel. The passage and operating space for replacing the chemical filter section must be confirmed during the design stage. If the existing system is tight on space, replacing the filter media may involve disassembly of other components.

Establish pre- and post-transformation verification

After the transformation is completed, the actual effect needs to be verified.

Preserve the pre-renovation baseline. Measure and record air volume, pressure difference, outlet concentration and operating status before modification. This is the starting point for subsequent comparisons. For specific detection methods, please refer to Discussion of sampling points for chemical filter performance verification .

Define shutdown, construction and recovery steps. Shutdowns or adjustments to operations may be required during retrofits. Construction steps, cleaning recovery and verification processes should be specified in the plan.

Retest after modification. Repeat the measurement of air volume, pressure difference, outlet concentration and particle cleanliness under the same conditions. Confirm that the system is back to normal and the chemical filtration section is meeting targets.

Record archiving. Modification plans, inspection data and operating records should be archived. During subsequent maintenance or renovation, you can quickly understand the system status. Please refer to the specific inspection records Discussion of what items should be checked during daily inspection of chemical filters .

Project judgment example

A certain clean room needs to add a chemical filtration section to the existing air conditioning box to handle the acid gas input from the outside.

The preliminary plan only selected a chemical filter based on the size of the existing filter frame. The calculation found that the new resistance increased the total resistance of the system by about 25%. The original fan margin was insufficient, and the terminal air volume would decrease. At the same time, the installation location of the filter section is tight and the maintenance access is blocked.

Adjustment plan: Select a thin chemical filter section to reduce resistance; adjust the installation position in the air conditioning box and reserve a maintenance channel; after calculating the fan working point, confirm that the air volume meets the requirements. After re-testing, the air volume and outlet concentration both reached the design targets.

In another project, the air volume was not re-measured after the renovation, and it was discovered that the terminal air supply was insufficient after running for a period of time. During the review, it was found that the final resistance of the chemical filtration section was much higher than the initial resistance, and the original fan could not maintain the air volume under the final resistance condition.

These two cases illustrate that before adding a chemical filter, the location, resistance, space and maintenance conditions must be evaluated, and retested after modification. involving When selecting a chemical filter product series , it is recommended that the site conditions, system data and target gases be provided to the supplier for verification.

Key points for selection and acceptance inspection

About Aili Industrial’s transformation assessment 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. For clean room renovation projects, site conditions, system data, target gases and installation space can be combined to assist in checking the configuration plan of the chemical filtration section. When the filter is matched with MAU, FFU, EFU and other equipment, the resistance, interface and maintenance methods can be confirmed uniformly.

Related products:Chemical filter product series、MAU box chemical filter、FFU comes with chemical filter . Providing site conditions, system data and target gases when enquiring, can help identify suitable modification solutions. The specific selection is subject to the technical documents and test results confirmed by the project.