What Are MAU, AHU, RCU, DDC, FCU, DHU, PAU and FFU in a Cleanroom?
Created on 2024.12.20
MAU, AHU, RCU, DDC, FCU, DHU, PAU, FFU in Cleanrooms: A Complete Guide
In cleanroom environments, precise air control is critical for industries like semiconductors, pharmaceuticals, and biotechnology. Terms like MAU, AHU, RCU, DDC, FCU, DHU, PAU, and FFU are essential components of HVAC and purification systems. This guide explains their roles, differences, and applications to help you design or maintain an efficient cleanroom.
1. MAU (Make-up Air Unit) – The Fresh Air Guardian
Function: Supplies and pre-treats outdoor air to maintain cleanroom pressure, humidity, and temperature.
Key Features:
- Filters dust, pollen, and contaminants
- Controls humidity via cooling coils (dehumidification) or steam humidifiers (winter)
- Critical in MAU+FFU+DCC systems for electronics and pharmaceutical cleanrooms.
Why It Matters: Ensures stable indoor air quality (IAQ) and compensates for air loss due to exhaust systems.
2. AHU (Air Handling Unit) – The Central Air Processor
Function: Conditions and circulates air by mixing fresh (MAU-supplied) and recirculated air.
Key Features:
- Integrates heating, cooling, filtration, and humidification
- Used in non-unidirectional airflow cleanrooms (ISO Class 6-9) .
vs. MAU: AHU recirculates air, while MAU handles 100% outdoor air.
3. RCU (Room Control Unit) – Localized Climate Manager
Function: Monitors and adjusts temperature, humidity, and airflow in individual rooms.
Applications:
- Ideal for multi-zone cleanrooms with varying environmental needs.
- Works with DDC systems for automated control 6.
4. DDC (Direct Digital Control) – The Smart Brain
Function: A microprocessor-based system automating HVAC operations.
Key Benefits:
- Adjusts MAU/AHU fan speeds, valve positions, and FCUs for optimal efficiency
- Enables remote monitoring and real-time adjustments 7.
5. FCU (Fan Coil Unit) – Compact Temperature Regulator
Function: Provides localized heating/cooling via chilled or hot water coils.
Best For:
- Small cleanrooms or supplemental cooling in FFU-dominated systems.
- Lowers energy costs by reducing central AHU load.
6. DHU (Dedicated Humidification Unit) – Precision Moisture Control
Function: Maintains strict humidity levels (e.g., 45±5% RH) in sensitive environments.
Technologies:
- Steam humidification (most common)
- Ultrasonic/Wetted media for low-humidity applications.
7. PAU (Pre-Cooling/Heating Air Unit) – Energy Saver
Function: Pre-treats outdoor air before MAU/AHU processing.
Advantages:
- Reduces thermal load on MAU, cutting energy use by 15-30% 4.
- Essential in extreme climates (desert/cold regions).
8. FFU (Fan Filter Unit) – Cleanliness Guarantor
Function: Provides HEPA/ULPA-filtered unidirectional airflow for ISO Class 1-5 cleanrooms.
Why Choose FFU?
- Modular design: Easy to install/replace.
- Energy-efficient: Lower static pressure vs. ducted systems.
- Often paired with MAU+DCC for temperature control.
How These Systems Work Together
A typical MAU+FFU+DCC cleanroom setup:
- MAU delivers dehumidified fresh air.
- FFUs recirculate filtered air for particle control.
- DCC (Dry Cooling Coil) handles temperature without humidity changes.
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