How to cooperate with MAU chemical filtration and terminal HEPA?

In clean rooms or equipment-side air supply systems, MAU chemical filtration sections and terminal HEPA often appear at the same time. One is responsible for the gaseous pollution brought in by the fresh air, and the other is responsible for particle control in the delivery area. It seems that each has its own business, but in actual operation, the cooperation between the two will directly affect the system resistance and protection effect.

A common misunderstanding is to regard the two as filter segments that can replace each other. No matter how efficient the terminal HEPA is, it has no ability to handle gaseous pollution; the MAU chemical filtration section treats the gas, but it cannot replace terminal particle control. The two need to work together, rather than choosing one over the other. Please refer to the specific division of labor Discussion of the difference between chemical filters and HEPA filters .

Explicit upstream input

The configuration of the MAU chemical filtration section should be based on the gas load of the fresh air.

What's in the new wind? Outdoor air may carry acidic gases, alkaline gases, organic vapors, or external odors. These components enter the system with fresh air. If not treated, they will directly enter the clean area or inside the equipment. For specific investigation methods, please refer to Discussion on why MAU needs to configure chemical filtration section .

Filter segment position and conditions. The location of the chemical filter section in the MAU will affect the temperature and humidity it faces. Whether to place it in front of or behind the surface cooler depends on the adaptability range of the filter material to temperature and humidity. For specific comparison, please refer to Discussion on whether the MAU chemical filter should be installed before or after the surface cooler .

Combined with pre-filter design. The dust in the fresh air will cover the chemical medium and shorten the service life. Setting up appropriate particle prefiltration before the chemical filtration section can reduce the media burden. Please refer to the specific division of labor Discussion on the division of labor between chemical filters and primary filters .

The terminal HEPA does not undertake general gas adsorption tasks. It is designed for particle control and has no handling capabilities for gas molecules. Putting gas control needs on HEPA will not solve the problem.

For the configuration method of MAU box-type chemical filter, please refer to Description of MAU Box Chemical Filter .

Check for new pollution indoors

MAU deals with the fresh air part, and the gas released indoors needs to be considered separately.

Indoor Equipment and Materials Release. The seals, lubricants, and process materials inside the equipment may release trace amounts of organic matter or specific gases during operation. This part of the pollution does not pass through the MAU and appears directly in the indoor air. For specific investigation methods, please refer to whether to do air sampling before choosing a chemical filter . Discuss

When the primary source is internal, air return or local control is required. If testing confirms that indoor releases are the main source, fresh air filtration alone is not enough. You can consider adding chemical filtration to the return air section or equipment end to reduce indoor concentration. For specific configuration, please refer to Discussion of what local contamination FFU plus chemical filter can handle .

Fresh air filtration is not a substitute for indoor source control. If there is a strong release source at a certain workstation, priority should be given to local exhaust to remove the pollutants before they spread. Terminal filtration deals with pollution that has entered the air.

Separate acceptance and maintenance

The acceptance methods of MAU chemical filtration section and terminal HEPA are different, and the maintenance basis is also different.

Particle side acceptance. The terminal HEPA performs efficiency confirmation, installation seal inspection and on-site leak detection according to the corresponding level. The detection methods and judgment standards are implemented according to the requirements of particle filters. Can be referenced HEPA high-efficiency filters . Testing instructions for

Gas side acceptance. The MAU chemical filtration section conducts inlet and outlet concentration tests based on target components to confirm the removal effect. The sampling points must be representative of the air before and after the filtration section, and the detection method must be suitable for the target gas. For specific methods, please refer to Discussion of sampling points for chemical filter performance verification .

Maintenance basis is different. The replacement of HEPA depends on the pressure difference and leak detection results; the replacement of the chemical filter section depends on the gas processing capacity consumption, and there may be no obvious pressure difference change. The maintenance rhythms of the two are different, and the ledgers must be recorded separately.

The effect of one filter cannot be inferred from another. Passing the particle test does not mean that the gas treatment meets the standards; passing the gas outlet concentration does not mean that the particle control meets the requirements. The two records are filed separately so that problems can be quickly located.

Check system resistance and fan operating point

When two filters are connected in series in the system, the resistance will be superimposed.

Total resistance calculation. Accumulate the initial resistance and final resistance of the MAU chemical filtration section, terminal HEPA, pre-filtration, air duct and other links, and compare it with the fan curve to confirm that the operating point is acceptable under the design air volume. For specific methods, please refer to Discussion of how much the added resistance of the chemical filter will increase the fan's electricity consumption .

The terminal air volume cannot be reduced. If the total system resistance increases after MAU adds a chemical filtration section, the air supply volume of the terminal HEPA may decrease. The number of air changes and airflow coverage in clean areas will be affected. When calculating, make sure that the terminal air volume is still within the design range.

Measure and confirm after installation. After the system is running, measure the pressure difference in each section of the MAU, the terminal air supply volume and the wind speed in key areas to confirm that they are consistent with the design values. If the air volume is low, you need to check whether it is a problem with the filter section resistance, the fan operating point, or the air duct.

Reserve sampling and maintenance channels

During the system design stage, conditions must be set aside for subsequent testing and maintenance.

Sampling point location. Sampling ports should be set up before and after the MAU chemical filtration section to facilitate tracking of outlet concentration. The leak detection port and sampling port of the terminal HEPA must also be reserved according to particle filtration requirements. For specific point selection, please refer to Discussion of sampling points for chemical filter performance verification .

Replace channel. The replacement cycle of the chemical filter section is different from that of HEPA. The maintenance operations of both may affect each other. When designing, confirm the respective removal paths to avoid replacing one of them without having to disassemble the other.

Record system operating data. Air volume, pressure difference, outlet concentration, and replacement date should be recorded. If the effect changes later, it can help determine whether it is chemical media consumption, HEPA blockage or system air volume changes.

Project judgment example

The HEPA leak test at the end of a certain clean room passed, and the particle index was normal, but there was still a slight gas problem at the workstation.

Troubleshooting process: First confirm that the terminal HEPA and air supply system are operating normally. Then the indoor air composition was tested and it was found that organic vapor released by indoor equipment was the main source, while the concentration of organic gas at the MAU fresh air inlet was low. The main source of pollution is indoors, not fresh air.

Adjustment direction: Add a chemical filtration section for organic gases in the indoor return air section or equipment end to deal with indoor releases. MAU's original particle filtration and terminal HEPA remain in their original configuration. After adjustment, the gas concentration at the workstation dropped, and the particle index was not affected.

This case illustrates: MAU chemical filtration and terminal HEPA each have a section of pipe. The effect of one cannot be used to infer the effect of the other. involving For the configuration of the chemical filter product series , it is recommended that fresh air data, indoor test results and system conditions be provided to the supplier for verification.

Key points for selection and acceptance inspection

About Aili Industrial’s air supply filtration package

The core of the cooperation between MAU chemical filtration and terminal HEPA is to match the fresh air gas load, indoor release, system resistance and maintenance conditions.

Aili Industrial has independent manufacturing capabilities in filters, motors, fans, control systems and sheet metal processing, and can provide chemical filter product series, HEPA filters and supporting air supply equipment. For systems involving both particle and gas control, fresh air detection data, indoor pollution sources, air volume and installation space can be combined to assist in checking the division of labor and interfaces between the chemical filtration section and the particle filtration section.

Related products:Chemical filter product series、MAU box chemical filter、HEPA high efficiency filter . When enquiring, provide fresh air gas data, indoor test results and particle requirements respectively, which will help confirm the appropriate combination plan. The specific configuration is subject to the technical documents and test results confirmed by the project.