Imagine you’re in a clean room similar to those in a hospital or electronics manufacturing facility. In these places, even tiny dust particles can cause huge problems. That’s why facilities take extra care to keep the air clean through the airflow.
It might sound simple at first – air comes in and moves out. Yet, even the direction of air movement can affect your product’s safety and quality!
So, what exactly is airflow, and how does it connect to the regulatory standards you’re expected to know? Today, we’ll walk you through the different types of airflow and why they matter.
What Is Airflow in a Clean Room?
Clean room airflow is all about controlling how filtered, clean air moves around the space.
As you may know, bacteria, dust, and other contaminants are always present in the air. Without a well-designed airflow system, these particles can end up on your products, affecting quality.
Airflow systems in clean rooms aren’t random. They’re engineered with precision. It’s something you need to get right, or your process can become unreliable.
This is especially necessary to stay compliant with GMP, HACCP, and ISO standards!
What Is Laminar (Unidirectional) Airflow In A Clean Room?
Laminar or unidirectional airflow in a clean room simply means the air is flowing in one direction. Just like a calm river, laminar airflow in a clean room sweeps particles away in a single smooth line.
Laminar flow in a clean room usually happens from the ceiling down to the floor, or from one side of the room to another.
This is important to prevent the particles from swirling around the room.
What Is Turbulent Airflow In A Clean Room?
Turbulent airflow, on the other hand, means the air may blow from many directions at once. The idea is that air gets pushed around, eliminating dead spots where particles may settle. After this, vents near the walls or floor suck the air out.
Turbulent airflow in a clean room is less efficient at removing contaminants. However, it’s also more cost-effective and is perfect for facilities with less strict requirements.
Why Airflow Matters in Clean Room Operations
For clean room operations, adjusting the airflow is one of the best ways to keep many variables under control. Here’s why it matters.
- Contamination Control
Aside from direct contact, air is a common way for microorganisms and other contaminants to spread inside a clean room.
Airflow is vital because it circulates the air in a controlled manner. This prevents microscopic particles from landing on your workspace and compromising safety.
- Maintaining Air Pressure Differentials
Another problem you have to consider is contaminated air flowing in from outside. When you crack a door open, you may feel the air entering or exiting the room. In some cases, this isn’t caused by wind, it’s pressure!
Generally, air naturally moves from areas with high pressure to places with lower pressure. Therefore, a clean room with positive or higher pressure pushes air out of any gaps, stopping dirty air from entering.
You can actually install Magnehelic gauges around the clean room to monitor the space’s positive pressure.
- Supporting Temperature and Humidity Control
Temperature and humidity are causes for concern for many products.
Food may spoil, and medicines may have chemical reactions if the environment is too hot. Excess humidity can cause bacteria and mold to grow.
Fortunately, airflow can control temperature and humidity!
By constantly bringing new air in, airflow can prevent hot spots and condensation from building up in the room. This creates a stable and safe environment for your products.
Cleanroom Classifications and Airflow Standards
Did you know that not all cleanrooms are the same? Different industries and processes need varying levels of cleanliness.
For instance, a GMP-certified food manufacturer may only need turbulent airflow to keep their products fresh. Meanwhile, pharmaceuticals may need sterile environments with stricter airflow requirements.
That’s where cleanroom classifications and airflow standards come in.
1. ISO Classifications and Air Change Rates
ISO classifications are international standards that tell us how clean the air inside a room must be. Each room receives a rating from 1 to 9, with 9 being the least clean based on the number of particles in the air.
Below is a summary of each classification.
| CleanroomClassification | Max no. of Particles | Details | Application |
| ISO 1 | 10/m³ | An ultra-sterile space for industries that need absolute precision and cleanliness. | Nanotechnology and biotechnology research, semiconductor manufacturing |
| ISO 2 | 100/m³ | Not as sterile as ISO 1, but still offers exceptional control over contaminants. | Sophisticated optics and specific biotechnology research |
| ISO 3 | 1000/m³ | A highly controlled environment with low particle count. | Pharmaceuticals |
| ISO 4 | 10,000/m³ | A notably low particle count that ensures high-quality manufacturing. | Pharmaceuticals, electronics assembly, optics |
| ISO 5 | 100,000/m³ | An environment that ensures critical processes are free from contaminants. | Medical device production |
| ISO 6 | 1,000,000/m³ | A controlled environment with a slightly higher particle tolerance. | Food processing, laboratories, and other manufacturing processes |
| ISO 7 | 10,000,000/m³ | A moderately controlled environment that minimizes contamination | Non-critical manufacturing, specialized production |
| ISO 8 | 35,200,000/m³ | A moderately controlled environment with less stringent cleanliness standards | General manufacturing, certain laboratories |
| ISO 9 | 352,000,000/m³ | A basic level of controlled airflow for places where minimal cleanliness is enough. | General assembly lines and typical office settings |
To uphold these standards, the facility must follow the correct air change rate. To give you an idea, the air change rate refers to the number of times a room is completely replaced with fresh, clean air per hour.
Here’s a quick guide on the air change rate and airflow type necessary for each classification.
| Cleanroom Classification | Air Change Rate | Required Airflow Type |
| ISO 1 | 500 to 700+ per hour | Unidirectional |
| ISO 2 | 480 to 720 | Unidirectional |
| ISO 3 | 400 to 600 | Mostly unidirectional |
| ISO 4 | 300 to 450 | Mixed |
| ISO 5 | 240 to 360 | Mixed |
| ISO 6 | 90 to 180 | Turbulent |
| ISO 7 | 60 to 120 | Turbulent |
| ISO 8 | 10 to 25 | Turbulent |
| ISO 9 | Less than 5 | Standard HVAC |
2. FDA, GMP, and Other Regulatory Guidelines
In FDA and GMP standards, cleanrooms are classified based on the number of airborne particles allowed in each zone.
- Grade A: Grade A is for the most critical areas where products may be exposed. These areas need unidirectional airflow and strict microbial control.
- Grade B: Grade B areas are places that surround Grade A zones.
- Grade C: Grade C areas have moderate contamination control. They’re usually for early manufacturing stages for products that will undergo cooking or sterilization later on.
- Grade D: Grade D zones are places that do not need much airflow control. Only minimal air ventilation is necessary.
3. Role of HEPA and ULPA filters
Finally, to keep the air clean, you’ll need to use HEPA and ULPA filters.
HEPA and ULPA filters are part of a purification system that removes particles, bacteria, and other contaminants from the air.
HEPA, which stands for high-efficiency particulate air, removes at least 99.97% of all airborne particles 0.3 microns large. On the other hand, ULPA, or ultra-low particulate air filters, remove particles smaller than 0.3 microns.
Both ensure the air entering your room is extremely clean and free from contaminants.
Conclusion
Controlling airflow may seem like a simple science, yet it’s incredibly important when it comes to clean rooms.
Airflow can directly affect the quality of your products as it minimizes contamination. Plus, it maintains air pressure in the room and keeps temperature and humidity stable. This is why the ISO sets strict standards for airflow in clean rooms.
Ultimately, learning about how airflow works protects you and your products. If your business has a clean room, we recommend investing in a well-designed airflow system for it.