Dust-free production line

1. How does a cleanroom production line achieve air purification?

Air purification in cleanroom production lines is primarily achieved through the following key stages:

1. Primary Filtration – Pre-filter: Handles large particles (dust, hair, etc.) in return air and fresh outdoor air.

It has relatively low filtration efficiency, mainly protecting subsequent HEPA filters and extending their lifespan.

2. Secondary Filtration – Medium/Sub-HEPA Filters: Intercepts smaller particles (1–5μm).

Further reduces the concentration of particles entering the clean area.

3. High-Efficiency Filtration – HEPA/ULPA Filters:
HEPA filter: Filtration efficiency ≥99.97% for particles ≥0.3μm.
ULPA filter: Filtration efficiency ≥99.999% for particles ≥0.12μm. This is the most crucial filtration stage in a cleanroom production line.

4. Airflow Organization Method

| Method | Characteristics | Typical Cleanliness Level |

| **Laminar Flow** (Unidirectional Flow) | Air flows at a uniform speed in a parallel direction, pushing out contaminants like a piston | ISO Class 5 and above (Class 100) |

| **Turbulent Flow** (Non-unidirectional Flow) | Reduces contaminant concentration through dilution | ISO 6–8 |

(1) Vertical Laminar Flow: Air is blown downwards from the ceiling HEPA filter and returned via the floor.

(2) Horizontal Laminar Flow: Air is blown from one wall to the opposite return air wall.
High-efficiency ceilings are filled with HEPA filters, forming a "clean air curtain".

5. Positive Pressure Maintenance
The air pressure in the clean area is slightly higher than outside (usually 5–15 Pa).
Prevents the infiltration of unpurified outside air.
Monitors and automatically adjusts the supply/return air ratio using a differential pressure gauge.

6. Temperature and Humidity Control and Circulation Processing
Fresh air and return air are mixed and then pass through the air conditioning unit (cooling/dehumidifying/reheating).
Supply air is filtered by HEPA before entering the clean room.
The circulation rate is much higher than in ordinary workshops (very frequent air changes per hour).

7. Auxiliary Purification Equipment

Air Shower: High-pressure clean air removes surface particles when personnel enter and exit.

Pass-through Window: Equipped with UV sterilization and self-cleaning functions for material transfer.

FFU (Fan Filter Unit): Modular installation, flexibly arranged on the cleanroom ceiling.

Overall Process Diagram:
Outdoor Fresh Air → Pre-filter → Medium-efficiency filter → Air Conditioning → HEPA filter → Cleanroom → Return air → Pre-filter → Circulation

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Exhaust air to the outside

**The entire system maintains the cleanliness standard of the production environment through multi-stage filtration + reasonable airflow organization + differential pressure control + strict personnel/material management.