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What is A CleanRoom?
A cleanroom is a controlled environment where pollutants like dust, airborne microbes, and aerosol particles are filtered out to provide the cleanest area possible. These specialized rooms are indispensable in modern industries where even microscopic contamination can compromise product quality.
Significance of CleanRoom Classification
Cleanroom classification provides a standardized method to measure and quantify air cleanliness levels. This standardization is crucial for industries where product quality directly correlates with environmental control. For example, in pharmaceutical manufacturing, a single particle can contaminate an entire batch of medication, potentially costing millions and endangering patient safety.
ISO 14644-1 Standard Overview
iso 14644-1 is the international standard for classifying air cleanliness in cleanrooms and controlled environments. This globally recognized standard has replaced many regional classifications, creating a unified system for cleanroom specification.
Core Concept: Particle size and count per cubic meter. The standard defines specific limits for airborne particulate contamination, with classifications ranging from ISO Class 1 (cleanest) to ISO Class 9 (least clean).
iso 14644-1 Cleanroom Classification System Explained
Understanding Core Parameters of ISO Classification
Particle Sizes
- 0.1 µm (ultrafine particles)
- 0.3 µm (common testing size)
- 0.5 µm (standard reference size)
- 1.0 µm (visible with microscope)
- 5.0 µm (human hair is 50-70µm)
Particle Count per Cubic Meter
This is the fundamental basis for classification. The standard specifies maximum allowable concentrations for particles equal to and larger than the specified sizes.
ISO Classification Levels Reference Table
| ISO Class | ≥0.1µm | ≥0.3µm | ≥0.5µm | ≥1.0µm | ≥5.0µm |
|---|---|---|---|---|---|
| ISO 5 | 100,000 | 23,700 | 3,520 | 832 | 29 |
| ISO 6 | 1,000,000 | 237,000 | 35,200 | 8,320 | 293 |
| ISO 7 | - | - | 352,000 | 83,200 | 2,930 |
| ISO 8 | - | - | 3,520,000 | 832,000 | 29,300 |
Table: Maximum allowable particle counts per cubic meter by particle size and ISO class
Particle Count Analysis Chart
This visualization demonstrates how particle count limits decrease exponentially as ISO classification becomes stricter. For example, ISO Class 5 allows 3,520 particles ≥0.5µm per m³, while ISO Class 8 allows 3,520,000 - a 1,000x difference.
Key ISO Cleanroom Classes (ISO 5, ISO 6, ISO 7, ISO 8) In-Depth Analysis
Key ISO Classes Comparison Table
| ISO Class | ≥0.5µm Particle Limit | Typical Applications | Airflow Pattern | Filtration Requirement | ACH Range |
|---|---|---|---|---|---|
| ISO 5 | 3,520 | Sterile filling, microelectronics | Unidirectional | HEPA/ULPA | 240-600 |
| ISO 6 | 35,200 | Pharma packaging, device mfg. | Mixed | HEPA | 90-180 |
| ISO 7 | 352,000 | Ante-rooms, food processing | Non-unidirectional | HEPA | 30-60 |
| ISO 8 | 3,520,000 | General production, packaging | Non-unidirectional | HEPA with pre-filters | 10-25 |
Critical Factors in Cleanroom design and Operation
A. cleanroom airflow Patterns
Unidirectional (Laminar) Flow
Used primarily in ISO 5 and higher classifications. Air moves in parallel streams with uniform velocity, typically at 0.45 m/s ±20%. This effectively sweeps particles away from critical processes.
Non-unidirectional (Turbulent) Flow
Used in ISO 7, 8 and lower classifications. Air movement is less controlled but sufficient for less critical applications. Relies on dilution principle with adequate air changes.
B. Filtration Systems
HEPA Filters
High Efficiency Particulate Air Filters remove 99.97% of particles ≥0.3µm. Essential for ISO 5-8 classifications. The utilizes specialized HEPA filtration to maintain food-grade purity standards in edible salt production.
ULPA Filters
Ultra Low Penetration Air Filters remove 99.999% of particles ≥0.12µm. Used in the most stringent applications beyond ISO 5 requirements.
Multi-Stage Filtration System
Most cleanrooms employ a multi-stage approach:
- Pre-filters (MERV 8-13): Capture larger particles, extending HEPA lifespan
- Intermediate filters (MERV 14-16): Additional protection for HEPA filters
- Final filters (HEPA/ULPA): Provide the final cleanliness level
C. Pressure Differential Control
Positive Pressure
Maintains higher pressure inside cleanroom than surrounding areas. Prevents infiltration of contaminants. Typical differential: 10-15 Pascals.
Negative Pressure
Maintains lower pressure inside containment areas. Prevents escape of hazardous materials. Used in pharmaceutical compounding or biohazard labs.
D. Air Changes Per Hour (ACH)
ACH measures how many times the total Air volume in a room is replaced per hour. Calculated as:
ACH = (Total Airflow in m³/h) ÷ (Room Volume in m³)
Recommended ACH Ranges by ISO Class:
- ISO 5: 240-600 ACH (typically 360 ACH for pharmaceutical applications)
- ISO 6: 90-180 ACH
- ISO 7: 30-60 ACH
- ISO 8: 10-25 ACH
Example Calculation:
For an ISO 7 Cleanroom measuring 10m × 8m × 3m (240m³) with recommended 45 ACH:
Required airflow = 240m³ × 45 ACH = 10,800 m³/h
This translates to approximately 4,500 CFM (cubic feet per minute) for HVAC system design.
iso 14644-1 vs. Federal Standard 209E Comparison
Historical Context
Federal Standard 209E was the predominant cleanroom classification standard in the United States until its official cancellation in 2001. The international ISO 14644-1 standard has since become the global benchmark, creating a unified classification system worldwide.
Key Differences
Measurement Units
FS 209E: Based on particles per cubic foot
ISO 14644-1: Based on particles per cubic meter
Classification Method
FS 209E: Used "Class" designation (Class 100, Class 1000, etc.)
ISO 14644-1: Uses "ISO Class" designation (ISO 5, ISO 6, etc.)
Classification Comparison Table
| ISO 14644-1 Class | Federal Standard 209E | ≥0.5µm Particles/m³ |
|---|---|---|
| ISO 3 | Class 1 | 102 |
| ISO 4 | Class 10 | 1,020 |
| ISO 5 | Class 100 | 3,520 |
| ISO 6 | Class 1,000 | 35,200 |
| ISO 7 | Class 10,000 | 352,000 |
| ISO 8 | Class 100,000 | 3,520,000 |
Note: Conversion based on 1 cubic meter = 35.3147 cubic feet
How to Select the Appropriate ISO Cleanroom Class?
Industry Regulations and Standards
GMP
Pharmaceutical Manufacturing
FDA
Medical Devices
EU GMP Annex 1
Sterile Products
SEMI
Semiconductor Industry
Product and Process Considerations
Product Sensitivity
Evaluate how susceptible your product is to particulate or microbial contamination:
- High sensitivity: Microchips, injectable drugs (ISO 5-6)
- Medium sensitivity: Medical devices, topical products (ISO 7)
- Low sensitivity: Packaging, assembly (ISO 8)
Process Requirements
Consider exposure time and contamination risk during manufacturing:
- Open vs. closed processes
- Manual vs. automated operations
- Product exposure duration
Risk Assessment
Conduct a formal risk analysis based on product and process characteristics. According to Deiiang™ Product Designer Jason.peng, "A thorough risk assessment should consider both particulate and microbial risks, process criticality, and the potential impact of contamination on final product quality."
Cleanroom Class Selection Decision Tree
