What is ACU? Considerations when using ACU

ACU stands for Air Clean Unit, a product widely used in warehouses, construction sites, factories, and hospitals. The use of ACU not only helps filter/clean the air but also ensures stable system operation, easy operation, and space-saving utilization. Let’s explore what ACU is, its structure, operating principles, and more with INTECH Service in the article below!

What is ACU?

ACU, which stands for Air Clean Unit, is a compact air treatment device integrating air conditioning and purification functions, providing optimal solutions for air conditioning and air filtration systems in various fields.

Similar to AHU, ACU is an air treatment device, but ACU integrates temperature and humidity control functions directly on the unit without the need for separate components like AHU. It’s this integration that makes it more convenient to operate, saving space more efficiently.

ACU is specifically designed for cleanroom systems that can ensure Class 1000 cleanliness level without the need for using ceiling grids. ACU allows the system to operate stably, creating vertically laminar flows through ducts placed on the ceiling.

With its effective air treatment capabilities, ACU is used in industries demanding high cleanliness levels such as pharmaceuticals, food, electronics, semiconductors, and healthcare.

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Structure of ACU

ACU has outstanding advantages in terms of compact size, space-saving, and energy efficiency. Although each application varies, ACU comes in different sizes and capacities. However, its main structure includes the following components:

Frame shell: Typically made of electrostatically painted steel for easy cleaning and insulated with a layer of thermal material inside. Some units are made of aluminum frame with insulated panel shell, but steel frame ACUs are still commonly used due to their ease of production in various sizes.
Filtration system: The installed filter membrane in ACU aims to filter dust and clean the airflow in the room according to the specific requirements of each room. Therefore, the filters in each unit may vary:
Pre-filter: Removes large particles such as dust and pet hair from the air.
HEPA/ULPA filter: Removes ultra-fine particles, including bacteria and viruses, from the air. HEPA can capture at least 99.97% of 0.3 micrometer-sized particles, while ULPA is more efficient.
For ACU in cleanrooms, G4 coarse filters and F8 bag filters are used to optimize device costs. ACU installed in cleanrooms uses G4 and H13 filters to ensure cleanliness according to customer requirements.
Temperature and humidity control unit: Unlike AHU, ACU can be installed directly in cleanrooms and comes with temperature and humidity control units.
The control unit is installed directly on the device, making it easy for customers to operate, control, and maintain.
The temperature and humidity control unit consists of protective equipment, roles, MCCBs, and commonly used control devices such as DDC, PLC, and HDMI display screens.
Other components: ACU also includes other parts such as supply fans, evaporators, heaters, and humidifiers. These parts function similarly to AHU.
The structure of ACU can vary depending on the specific requirements of the application, such as the controlled area size, cleanliness level requirements, and specific industry standards. Typically, ACU is designed for easy maintenance and cleaning, ensuring the highest air filtration efficiency.

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Operation principle of ACU

Fresh air passes through the G4 filter => Evaporator => Heater => Humidifier => Supply fan => HEPA filter => Cleanroom.

ACU operates by creating layers of airflow vertically through duct systems placed above the ceiling.

The components inside the device play a role in treating fresh air brought in from the outside, helping to regulate and clean the air before supplying it to the cleanroom.

This principle can be applied to most cleanroom models, making it the optimal choice for installation under any technical conditions or scale characteristics.

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Classification of ACU

Direct blow ACU

Direct blow ACU is designed to deliver clean air directly to the controlled area without going through duct systems. This type of ACU is often used in small cleanrooms and is installed directly in the cleanroom, resembling a floor-mounted air conditioner, with the return air at the bottom and direct blowout into the room above.

Features of direct blow ACU include:

Direct Blow: ACU has a fan or direct air blowing system to deliver clean air to the controlled area without ducts.
Fan or Blower Motor: To create a clean air stream and deliver it to the working area, ACU is usually equipped with a powerful fan or blower motor.
Airflow Control: Direct blow ACU can adjust the clean air stream to ensure even and efficient air distribution.
Direct blow ACU can be mobile or fixed at specific locations. This helps provide clean air directly to the necessary areas without the need for complex ductwork.

The advantages of direct blow ACU include easy installation and operation, cost savings due to simple design and compact size. However, the drawbacks include high noise levels, inadequate temperature control, and less efficient air filtration.

Ducted ACU

Ducted ACU is designed to connect to duct systems to deliver clean air to areas that need control. This type of ACU is often used in large cleanrooms or areas with high cleanliness requirements.

Ducted ACU has a supply port connected to the duct system and air outlet, or the HVAC system (Heating, Ventilation, and Air Conditioning) of the building or specific environment. Instead of blowing directly into the room, the supply air of ACU is blown into the duct and evenly distributed in the room. Ducted ACU is usually equipped with air filters (HEPA or ULPA) and can control the temperature and humidity of the air.

The advantages of ducted ACU include more uniform temperatures in room areas compared to direct blow ACU, high air filtration efficiency, and lower noise levels. The downside is that it costs more than direct blow ACU, and system installation is more complex.

Ducted ACU is often used in large cleanrooms or manufacturing environments that require overall air quality control.

Considerations when using ACU

Ensure the setup and adjustment of the ACU system to meet the specific requirements of the environment. This includes setting parameters such as temperature, humidity, airflow, and other requirements.
Monitor the performance of the ACU system by regularly checking parameters such as the quality of the output air, airflow, temperature, and humidity. If any issues are detected, necessary repairs or adjustments can be made.
Follow all safety regulations related to operating and using the ACU system.
Perform regular checks of the ACU system to ensure efficient operation. Regularly checking filters, control systems, sensors, and other components will help ensure that the ACU operates correctly.
Conduct regular maintenance and servicing of the ACU to ensure stable operation and prolong its lifespan.

Hope the article above provides useful information about ACU for our readers. INTECH Service is a professional provider specializing in renovating, testing, upgrading the quality of cleanrooms, HVAC systems accurately. If you have any further questions that need clarification, please contact us right away.