Whether it is feasible to reduce the amount of fresh air combined with chemical filtration requires checking necessary ventilation, personnel and process requirements, carbon dioxide, pressure difference and related pollutants at the same time. Chemical filtration cannot be used as an unconditional reason to reduce fresh air. There are some things in the fresh air that the filter cannot control.

Xinfeng undertakes more than just filtering tasks

When fresh air enters a clean room or workshop, its tasks include supplementing the oxygen needed for personnel breathing, diluting carbon dioxide, maintaining positive pressure, eliminating process releases, and maintaining air flow organization. Chemical filtration can process the target gas that passes through the filtration section, and has no direct effect on conditions such as carbon dioxide, oxygen content and pressure difference. If the purpose of reducing fresh air is to save energy, but the carbon dioxide concentration, pressure difference or personnel comfort level in the room is close to the lower limit, then no matter how strong the chemical filtration is, it cannot solve these problems. To determine whether fresh air can be reduced, we must first see whether there is still room for various tasks of fresh air.

Filter coverage and filter effect are two different things

The chemical filter only processes the part of the air that passes through it, and the air in the unfiltered section will not be purified due to the presence of the filter element. Reducing fresh air means that the proportion of return air increases, and indoor air relies more on circulating filtration. If the location, air volume, and media configuration of the circulating filter section can cover the main indoor gas sources, increasing the return air ratio may be feasible for gas control; however, if the pollution source is downstream of the filter section, local exhaust is insufficient, or there are dead corners in the airflow organization, increasing the return air ratio may allow pollutants to accumulate indoors. Regarding the relationship between the position of the filter section and the air path, please refer toThe indoor odor is different from the fresh air entrance odor. How should I investigate?。

Different gas objects should be judged separately

After the fresh air decreases, the change directions of various pollutants are not necessarily the same. Externally input acidic gases and organic emissions will decrease as the fresh air volume decreases; indoor carbon dioxide, personnel metabolites, and process releases may increase due to the decrease in air exchange times. Chemical filtration may help with the former, but not with the latter. Therefore, the fresh air reduction plan should classify the gas objects: which ones are diluted by fresh air, which ones are treated by filtration, and which ones work together. Only by making a clear distinction can we judge how much fresh air can be replaced by chemical filtration.

Pressure differential and airflow organization need to be rechecked

Reducing the amount of fresh air will change the room pressure difference and the proportion of air supply and return, thereby affecting air flow organization and cleanliness. A reduction in positive pressure may cause air to infiltrate into adjacent areas, and changes in airflow organization may cause stagnation in certain areas. These changes are interrelated with gas control, and you cannot just look at gas detection data. After the fresh air reduction plan is implemented, the pressure difference, air flow and gas indicators should be checked under normal and boundary working conditions to confirm that the system status is still within the controllable range. Regarding the selection of fresh air and filter sections, please refer toDoes the chemical filter section need to be reselected when the fresh air volume changes seasonally?。

Aili industrial supporting equipment

For projects that reduce fresh air combined with chemical filtration, we usually recommend that customers first clearly list the tasks undertaken by the fresh air, and then determine which part of them can be replaced by filtration. Aili Industry can provide selection packages for box-type, flat-plate and V-type chemical filtration products. For box-type MAU packages, please refer toMAU box type chemical filter , product series can be viewedChemical filter product range . The V-shaped structure provides a larger filtration area in the same box space, which helps control surface speed and resistance when the circulating air volume increases. Device-side applications can useChemical filter FFU type, integrated chemical adsorption layer withHEPA/ULPA filter particle filtration, the circulation filtration section can be adjusted and configured according to the return air ratio. The manufacturing end covers independent R&D and production of motors and fans, control systems, sheet metal and complete machine assembly. Fresh air ratio, return air filtration and fan operating points can be checked in the same package, and non-standard air paths can be adjusted according to on-site conditions. The specific gas effect, applicable environment and replacement cycle still need to be verified based on the corresponding configuration data and on-site working conditions. The actual results are subject to on-site leak detection and gas detection results.

Related questions and answers

How much can the fresh air volume be reduced by installing a chemical filter?
There is no uniform proportion. It depends on how much margin is left for each task of fresh air, which gases can be covered by circulating filtration, and whether the pressure difference and carbon dioxide are allowed. It should be determined after checking item by item.

Can chemical filtration deal with the increase in carbon dioxide after reducing fresh air?
Conventional chemical filters are not responsible for carbon dioxide treatment. Carbon dioxide mainly depends on fresh air dilution and personnel management. Before reducing fresh air, it should be confirmed that the carbon dioxide concentration is still within the required range.

Can Aili Industrial help check the fresh air reduction plan?
It can be combined with fresh air tasks, circulation filtration configuration and room pressure difference conditions to help check the scope of chemical filtration coverage. The specific plan needs to be confirmed based on product data and on-site working conditions.

Related articles

• Can chemical filters reduce carbon dioxide in the air?

• Can the chemical filter modification be done together with the energy-saving modification of the air conditioning box?

• How does a chemical filter energy saving program maintain gas control goals?

• Can chemical filters support partial return air reuse?

Key points for selection and acceptance inspection