How does the fresh air task of the clean room MAU correspond to the process exhaust?

The clean room MAU mainly handles supplementary air according to the system design. The fresh air demand needs to be checked together with process exhaust, personnel ventilation, leakage and pressure difference balance. The MAU air volume is not equal to the total circulating air volume of the clean room, and the air recirculation undertaken by the FFU or circulation unit cannot be fully included in the fresh air.

Establish independent lists along the direction of supplementary wind

First list the normal exhaust air, duty exhaust air and operating states that can occur at the same time for each equipment, and then correspond to the service area. Then the designer will check the fresh air and regional air balance. If part of the exhaust air is already taken by another supplementary air system, the interface should be marked to avoid double counting.

Process air exhaust must be distinguished between continuous, intermittent and maintenance states, and simultaneous operating conditions must be explained; pressure difference balance must consider the joint effects of building leakage, return air, and supply and exhaust air; circulating air supply must be calculated separately for environmental coverage and load treatment, and shall not be considered as new outdoor air. The three types of air volume have different calibers and cannot be added together as fresh air volume. For the relationship between fresh air volume 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?。

Process exhaust is one of the main basis for supplementary air volume

The exhaust air volume of process equipment usually determines the lower limit of the makeup air volume. In areas with large exhaust air volume, if the fresh air supply is insufficient, the room pressure difference may not be maintained, the exhaust effect will be reduced, and even airflow in adjacent areas may be reversed. The exhaust list should be organized according to equipment number, exhaust volume, operating period and simultaneous use coefficient, and cannot only give a total exhaust volume.

The corresponding relationship between exhaust air and supplementary air is also affected by whether the exhaust air has been treated and whether it can be reused. Exhaust air containing high-concentration process releases is usually discharged independently and should not be returned to the air supply system. Please refer toWhat do the chemical filter and particle filter of the air conditioning box deal with respectively? . The exhaust path and supply air path should be marked separately to avoid being mixed into one line on the system diagram.

Fresh air for personnel and maintenance of pressure difference are two other constraints.

The fresh air volume for personnel is usually determined based on the number of personnel and fresh air standards, and is a basic requirement to protect personnel health. Pressure differential maintenance requires consideration of building leaks, door openings and exhaust fluctuations. These two items together with the process exhaust air constitute the constraints on the fresh air volume. During design, one or a combination of them plays a controlling role.

If the clean room pressure difference is qualified but external gas still enters, please refer toIf the clean room pressure difference is qualified, why can external gas still enter? . The relationship between pressure difference control and fresh air volume also affects the operation strategy of MAU.

MAU air volume is not equal to total circulating air volume

The total circulating air volume of the clean room is usually borne by the FFU or circulation unit, and the MAU handles the make-up air. Taking the MAU air volume as the total circulating air volume will overestimate the proportion of fresh air or underestimate the circulation processing requirements. On the contrary, counting the FFU circulating air volume into the fresh air volume will cause the supplementary air volume calculation to be too large.

How the circulating air handling unit bears the indoor load can be referred toWhat indoor loads should the circulating air handling unit be selected based on? . The division of labor between FFU and MAU can be combinedFFU fan filter unit understand. When the MAU supply air is mixed upstream of the circulation unit, how to consider the inlet status of the circulation unit, please refer toHow to consider the incorporation of MAU fresh air into the air inlet status of the circulating unit?。

After the quantity is determined, the air supply status will be handed over.

After the air supply volume is determined, it is also necessary to agree on the temperature and humidity or moisture content that the MAU will treat the air to, and check the cold source and external pressure of the machine. Only giving the total fresh air volume without explaining the exhaust air changes may make it impossible to determine the minimum operating conditions and adjustment range of the unit.

The MAU air supply status is related to the circulation unit inlet status. How to select the surface cooler according to the inlet and outlet air status, please refer toHow to select the type of air conditioner cooler according to the air inlet and outlet conditions? . How to write the pressure caliber clearly, please refer toWhat is the difference between static pressure, total pressure and static pressure outside the air conditioner box? . When the fresh air ratio changes, you can refer toHow is the proportion of new return air to the air-conditioning box determined by project requirements?。

Changes in operating modes should be checked separately

The demand for supplementary air volume may be different during normal production, duty, maintenance and partial shutdown of exhaust equipment. If the MAU is selected only according to the maximum fresh air volume, it may be difficult to adjust under low load; if the MAU is selected only according to normal working conditions, the air supply may be insufficient when the exhaust air is fully opened. The operating mode table should list the exhaust air volume, fresh air volume and pressure difference requirements under each state to facilitate checking of the MAU's adjustment range.

For issues involving partial load regulation, please refer toWhy should we check the efficiency range when selecting air-conditioning box fans? . For the difference between the opening of the fresh air valve and return air valve and the actual air volume, please refer toCan the opening of the fresh air valve and return air valve directly represent the air mixing ratio?。

Aili industrial supporting equipment

Aili Industrial MAU plan can be checked together with FFU, filter and control requirements; it is recommended to submit an exhaust list divided by regions to clarify the task boundaries of equipment and clean systems. Aili's industrial manufacturing end covers independent R&D and production of motors and fans, control systems, sheet metal, air filters and complete machine assembly. The interfaces and operating points of MAU, FFU and circulation units can be aligned in the same package; non-standard air volume can be adjusted according to the project exhaust conditions.

Product form can be viewedAir handling unit andFan box page; clean air supply package can be combinedFFU fan filter unit andEFU equipment end fan filter unit verification; terminal particle filtration can be combinedHEPA/ULPA filter confirmation; when it comes to gaseous pollution control, you can communicate separatelyChemical filter solutions. The specific air volume, air supply status and delivery scope still need to be verified based on the corresponding configuration data and on-site working conditions. The actual effect is subject to on-site air volume balance and performance test results.

Submit project parameters:https://ailigy.com/contactus.html

Related questions and answers

Is MAU air volume the total air supply volume of the clean room?
no. MAU handles supplementary air, and the total circulating air volume is usually borne by FFU or circulating unit, and the two cannot be confused.

Can process exhaust air volume be directly used as fresh air volume?
cannot be directly equated. The amount of fresh air should also consider fresh air for personnel, pressure difference maintenance and building leakage, whichever conditions play a controlling role.

Can Aili Industrial help check the correspondence between MAU and exhaust air?
The MAU configuration and interface can be checked based on the exhaust air list and regional air volume balance. The specific plan needs to be confirmed based on the project system design.

Related articles

1. How to calculate the fresh air volume and total air supply volume of the air conditioning box separately?

2. How to consider the incorporation of MAU fresh air into the air inlet status of the circulating unit?

3. How is the proportion of new return air to the air-conditioning box determined by project requirements?

4. What indoor loads should the circulating air handling unit be selected based on?

Key points for selection and acceptance inspection