How to select the air conditioning box filter grade based on the inlet air conditions?

The filtration level of the air conditioning box should be determined based on the inlet particle characteristics, concentration changes, downstream targets and operation and maintenance conditions. Outdoor fresh air, ordinary return air and return air that may contain process dust cannot simply use the same combination. Clear evaluation standards and particle sizes should also be used to compare filtration levels.

First create a realistic picture of the inlet air

Information may include outdoor seasonal dust, adjacent construction, return air sources, and process releases. If the particles are oily, hygroscopic or sticky, the suitability of the filter material and maintenance methods must also be evaluated separately. For air with specific process risks, professional design should first confirm whether it can be reused. The return air plan cannot be determined solely by improving the filtration level.

The particle characteristics should include particle size distribution, concentration, viscosity and seasonal changes; the control objectives should include downstream component protection and final air cleaning tasks; the operating conditions should include rated air volume, resistance budget, maintenance and replacement conditions. The three types of information correspond to different selection criteria, and you cannot just give one entrance photo. How to determine the filter classification configuration, please refer toHow to configure the primary-efficiency and medium-efficiency filters of air-conditioning boxes in different stages?。

The particle conditions of outdoor fresh air and return air are different

The particle concentration and particle size distribution of outdoor fresh air vary greatly with the season, weather and surrounding environment, and may contain pollen, road dust and construction dust. Normal return air typically has a lower particle concentration but may contain process-generated fine particles. Return air containing process dust may contain metal shavings, fibers or oily particles, which requires higher filter material requirements.

How the fresh air tasks of the clean room MAU correspond to the process exhaust air, please refer toHow does the fresh air task of the clean room MAU correspond to the process exhaust air? . For the relationship between fresh air and total air supply volume, please refer toHow to calculate the fresh air volume and total air supply volume of the air conditioning box separately?。

The downstream protection object determines the lower limit of the filtering level

Filter ratings are required to protect downstream components and final air quality. When protecting coils and fans, the initial or medium efficiency may be sufficient; when protecting high-efficiency filters, the medium-efficiency level needs to be increased accordingly; when there is a high-efficiency filter at the end of the clean room, the upstream filtration and protection need to match. The more sensitive the downstream object, the higher the filtering level and configuration requirements.

Whether the high-efficiency filter should be placed inside the machine or at the end, please refer toShould the high-efficiency filter of the air-conditioning box be placed inside the machine or at the end of the air supply? . For particle protection before the chemical filtration section, please refer toHow to judge whether the MAU chemical filtration section is arranged before or after the surface cooler?。

The comparison caliber of filtering levels should be unified

The filtering levels under different evaluation systems cannot be directly converted by letters or numbers. When comparing filters, you should confirm the standard used, particle size aperture, test method and rated air volume. Filters marked with a certain grade may have different efficiency data under different test conditions. Procurement documents should indicate the evaluation system and version used.

What applicable standards should be listed in the technical documents for purchasing air-conditioning boxes? Please refer toWhat applicable standards should be listed in the technical documents for purchasing air-conditioning boxes? . How to compare the gas test reports of different chemical filter manufacturers, please refer toHow to compare gas test reports from different chemical filter manufacturers?。

Operating environment and maintenance conditions influence grade selection

Projects with high inlet particle concentrations, poor maintenance, or inconvenient replacement may require higher dust holding capacities or more durable filtration configurations. Construction dust, coastal salt spray or process dust may alter actual loads. Increasing filter levels will increase resistance and replacement costs, requiring a balance between protection effectiveness and operating costs.

How to determine the maintenance cycle according to the operating environment, please refer toHow to determine the maintenance cycle of air conditioning box according to the operating environment? . How to configure the primary and medium-efficiency filters in stages, please refer toHow to configure the primary-efficiency and medium-efficiency filters of air-conditioning boxes in different stages?。

How to proceed when there is no detection data

You can first collect air sources, historical filter material dust accumulation and on-site environmental photos, indicate tentative conditions, and then arrange necessary measurements. The grade names under different evaluation systems cannot be converted directly based on letters or numbers. Technical confirmation should record the system used and performance data to maintain a consistent basis for subsequent filter material replacement.

How to write an inquiry form for air-conditioning boxes so that different quotes can be compared, please refer toHow to write an inquiry form for air-conditioning boxes so that different quotes can be compared? . For condition checks before starting the machine for the first time, please refer toWhat conditions need to be checked before the air conditioner is turned on for the first time?。

Aili industrial supporting equipment

Aili Industrial can check the filter configuration based on imported data and provide existing filter material models and usage records to help determine which level the changes should fall into. Aili Industrial has air filter manufacturing capabilities, and can jointly confirm the filter size, grade, headwind speed, initial resistance and installation method with the air-conditioning box structure; the manufacturing end covers independent research and development and production of motors and fans, control systems, sheet metal, air filters and complete machine assembly. The filter section and box interface can be aligned in the same package.

Product form can be viewedAir handling unit andFan box page; terminal particle filtration can be combinedHEPA/ULPA filter confirmation; clean air supply package can be combinedFFU fan filter unit andCheck the fan filter unit at the EFU equipment end ; when it comes to gaseous pollution control, you can communicate separatelyChemical filter solutions. The specific filtration level, applicable conditions and delivery scope still need to be verified based on the corresponding configuration data and on-site working conditions. Actual results are subject to on-site leak detection and particle test results.

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Related questions and answers

Can the same filter grade be used for outdoor fresh air and return air?
uncertain. The particle characteristics of the two are different. The particle concentration and particle size distribution of outdoor fresh air may be more complex and need to be evaluated separately.

Is the higher the filtration level, the better?
no. Increasing the grade will increase resistance and replacement costs, and should be selected in a balanced manner based on downstream protection objects and inlet conditions.

Can Aili Industrial help select the filtration grade?
The filter configuration can be checked based on the inlet air conditions, downstream objectives and operation and maintenance requirements. The specific grade needs to be confirmed based on product information and on-site working conditions.

Related articles

1. How to configure the primary-efficiency and medium-efficiency filters of air-conditioning boxes in different stages?

2. Should the high-efficiency filter of the air-conditioning box be placed inside the machine or at the end of the air supply?

3. How to determine the maintenance cycle of air conditioning box according to the operating environment?

4. What applicable standards should be listed in the technical documents for purchasing air-conditioning boxes?

Key points for selection and acceptance inspection