The clean room is contaminated by acid gas and solvent at the same time. How to combine filtration solutions?

Gaseous pollution occurs in clean rooms, and sometimes it is not a single component. The coexistence of acid gas and solvent vapor is not uncommon in semiconductor, panel, precision electronics and laboratory projects.

These two types of pollutants have different molecular properties and require different filter media. Acid gas requires a medium for acidic components, and solvent vapor requires a medium for organic matter. Mixing them together and choosing a universal filter material often fails to take care of both ends. The core of the combined plan is to clearly identify the two types of pollution separately, and then decide how to deal with them together. For specific selection principles, please refer to Discussion on why chemical filters should be selected according to the target gas .

First confirm the common air path

The first step in the combined plan is to find out whether the two types of pollution follow the same path.

Homogenous or heterologous. Acid gas and solvent vapor may come from the same process or from different areas. Processing locations can be placed together if they come from the same equipment or airflow. If the sources are dispersed, partitioning may be required. For specific investigation methods, please refer to whether to do air sampling before choosing a chemical filter . Discuss

Whether to enter the same filter section. If both types of pollution pass through the same filter section, a combined configuration needs to be considered. If only part of the airflow passes through and the other part is bypassed, the processing location and method must be adjusted accordingly. Please refer to the specific location selection which air handling systems are appropriate for chemical filters to be installed in . Discussion of

Is there any cross-regional transmission? Acid gas may come from external fresh air, and solvent vapor may be released from indoor processes. If the two sources are different, the treatment location may be one in the fresh air section and the other in the return air section. For specific differences, please refer to Why does MAU need to configure the chemical filter section and Discussion of what localized contamination can be treated by FFU plus chemical filter .

First determine whether they enter the same filter section, and then decide on the combination method. If the two types of pollution do not follow the same path, they do not necessarily need to be combined in the same section.

Check media combination basis

After confirming that combined processing is required, check the media configuration.

Acid gases and solvents require different media. Acid gas usually requires alkaline impregnation or special acid gas adsorption media, and solvent vapor usually requires activated carbon or special media suitable for organic gases. For specific differences, please refer to Can chemical filters remove sulfur dioxide from the air ? Discussion on how to choose an air chemical filter for toluene pollution .

Don't just look at the multi-gas label. Some products are labeled 'can handle acid gas and organic matter', but the specific performance requires corresponding test data. Removal efficiencies and capacities may vary for different components, and labels should not be taken as proof that requirements are met for all gases. For specific report interpretation, please refer to Discussion of why chemical filter performance reports list specific target gases .

Mixed pollution may compete. When multiple gases exist at the same time, different components may compete for adsorption sites, or some components may react preferentially, affecting the overall performance. When selecting, check the data according to mixed conditions, or use hierarchical configuration to process them separately. For specific differences, please refer to Discussion of whether chemical filters can handle both particulate matter and gases .

Single component data cannot be directly extrapolated to mixed conditions. The data of toluene cannot explain the effect on acidic gases, and the data of acidic gases cannot explain the effect on organic matter. Both should be checked separately.

Combination sequence and configuration method

There are different ways to implement the combination scheme, and the order and structure need to be confirmed.

Layered configuration. If acid gas and solvent vapor require different media, they can be loaded in layers in the same filtration section, or two independent filtration sections can be set up. One layer handles acid gases and one layer handles organic matter. Please refer to the specific order Discussion of the common product forms of chemical filters .

Series or parallel connection. When connected in series, all airflow passes through the two layers of media in sequence. When connected in parallel, the airflow is divided into two paths, which are processed separately and then merged. Series configurations are more common, but the resistance stacks up. The parallel structure has requirements for air volume distribution. For specific air volume distribution, please refer to Discussion on whether the chemical filter air volume should be selected based on the total air volume of the system or the air volume of a single unit .

How to decide the order. If two types of media are sensitive to each other's products or environment, the sequence may need to be adjusted. For example, the performance of some sour gas media decreases in the presence of organic matter, or the organic media is sensitive to acidic environments. The specific sequence should be confirmed by product and system.

Partition processing. If the sources of acid gas and solvent are different, filter sections can be set up in their respective areas and do not have to be combined together. For specific phased implementation, please refer to Discussion on whether chemical filters can be installed step by step in different areas .

System cooperation and maintenance

The operation and maintenance of the combined solution should also be considered together.

Resistance stacks up. The resistance of the two filter sections is added together. Whether the system fan can withstand it needs to be calculated based on the actual working point. For specific methods, please refer to Discussion of how much the added resistance of the chemical filter will increase the fan's electricity consumption .

Replacement cycles are out of sync. Sour gas media and organic media may be consumed at different rates. When replacing one, the other may still have some left. The maintenance ledger should be recorded in layers and the replacement basis should be set separately. For specific management methods, please refer to Discussion on why the chemical filter replacement cycle cannot be calculated as half a year .

Verify each goal individually. Export testing needs to cover the main ingredients. The decrease in acid gas concentration cannot prove that the organic vapor has been processed. The sampling method should be suitable for the target gas. For specific methods, please refer to Discussion of sampling points for chemical filter performance verification .

Check synchronously during maintenance. When replacing one layer of media, check the condition and seal of the other layer. Sealing requirements for combined structures may be higher. For specific inspection methods, please refer to Discussion on how to check frame bypass after chemical filter installation .

Project judgment example

Acid gas and organic solvent vapor were detected simultaneously in a clean room. The acid gas comes from external fresh air, and the solvent vapor comes from the indoor cleaning process.

The preliminary plan considers mixing two media in the same return air filter section. After evaluation, it was found that mixed filling may lead to uneven airflow distribution, and the two layers of media consume at different rates, making replacement inconvenient.

Adjustment plan: Set up a chemical filtration section for acidic gases in the fresh air section to handle external input; set up a chemical filtration section for organic vapor in the indoor return air section to handle internal releases. The two sections check the air volume, resistance and replacement cycle respectively. After adjustment, the outlet concentrations of fresh air and return air meet the requirements, and maintenance is managed separately.

This case shows that the combination of acid gas and solvent pollution does not necessarily mean that the two media are packed together, but can also be processed separately according to the source. involving When selecting a chemical filter product series , it is recommended that the components, concentrations and sources of the two types of pollution be provided to the supplier for verification.

Key points for selection and acceptance inspection

About Aili Industrial’s combined filtration 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 projects with both acid gas and solvent pollution, the target gas, concentration range, source path and system conditions can be combined to assist in checking the combined filtration plan and configuration method.

Related products:Chemical filter product series、MAU box chemical filter、FFU comes with chemical filter . When enquiring, provide the target composition and concentration of acid gas and solvent respectively, which will help confirm the appropriate combination plan. The specific selection is subject to the technical documents and test results confirmed by the project.