HVAC & ACH: Ensuring Cleanroom Performance and Compliance
The Role of HVAC in Cleanroom Design
HVAC (Heating, Ventilation, and Air Conditioning) plays a crucial role in maintaining the necessary conditions for a cleanroom. Cleanrooms rely heavily on HVAC systems to control the flow of air, filter contaminants, and maintain temperature and humidity levels.
Proper HVAC calculations require a blend of technical knowledge, an understanding of particle-generating processes, and experience with cleanroom-specific needs.
It is essential to work with an HVAC specialist who has experience in cleanroom design to ensure that your system is appropriately sized, designed, and optimized to meet the cleanliness standards for your specific industry.
Understanding ACH and ISO Classifications
ISO 14644-1:2015 does not specify exact air changes per hour (ACH) for each cleanroom class because the required ACH depends on various factors, such as the type of activity occurring within the room, the number of people present, and the process’s potential to generate airborne particles.
However, the ISO purity level (such as ISO 8, ISO 7, ISO 6, and ISO 5) provides an indication of the ACH range you should aim for.
While the ISO class sets the maximum particle concentration limits in the air, the ACH determines how frequently the air is exchanged to achieve and maintain those limits.
A cleanroom with low particle-generating activities may require fewer air changes than a cleanroom performing processes that generate significant particulate matter.
Rule of Thumb for ACH Based on Cleanroom ISO 14644 Classifications
Here are some general ACH recommendations based on the ISO classification of the cleanroom:
ISO 8: 10-30 ACH
For environments where contamination is relatively low and particle generation is minimal.
ISO 7: 30-65 ACH
Cleanrooms requiring moderate contamination control with more stringent requirements on particle count.
ISO 6: 80-150 ACH
Cleanrooms with more stringent requirements for contamination control, typically found in industries like electronics.
ISO 5: 200-450 ACH
Cleanrooms where the highest level of cleanliness is necessary, typically for pharmaceutical production or high-precision electronics.
These ACH ranges are intended as rules of thumb based on typical ISO 14644 cleanroom requirements and the potential for particle generation.
However, each cleanroom is unique, and these numbers can vary depending on the processes, the equipment used, and the number of personnel in the room.
HVAC Requirements for EU GMP Cleanrooms
For EU GMP (Good Manufacturing Practice) cleanrooms, there are specific ACH guidelines based on the cleanroom grade.
These recommendations ensure that air changes are sufficient for controlling contamination in environments used for pharmaceutical manufacturing, biotechnology, and other regulated industries:
GMP D: 5-10 ACH
GMP C: 10-15 ACH
GMP B: 20-25 ACH
GMP A: 30-35 ACH
If there is significant particle generation in the cleanroom process or many people working in the room, you may need to select the higher value within the recommended range to ensure the cleanroom’s cleanliness level is maintained.
Factors Influencing ACH Calculations
ACH calculations depend on several factors, and it is essential to understand how each one affects the design of your HVAC system:
Process Characteristics:
Processes that generate more airborne particles (such as manufacturing or compounding activities) require higher ACH values to maintain cleanliness.
Number of Personnel:
More people working in the cleanroom can increase the number of particles in the air, requiring more frequent air changes.
Size and Layout of the Cleanroom:
Larger cleanrooms may require more air changes to maintain uniform cleanliness throughout the space.
Equipment:
Sensitive equipment, especially in electronics or pharmaceutical industries, may need additional airflow control to prevent contamination.
Since ACH is not a one-size-fits-all figure, the HVAC engineer will need to perform the necessary calculations based on the specific requirements of the cleanroom's operations.
These calculations should take into account the particle-generating potential of the processes, the design, and the desired cleanroom classification.
The Importance of Proper HVAC Design
The right HVAC system is crucial for maintaining a stable and contamination-free environment. A well-designed HVAC system helps ensure:
Optimal Air Quality:
By regulating air changes, the system filters out contaminants and helps maintain the required particle concentration.
Regulatory Compliance:
Following ACH guidelines ensures that the cleanroom remains compliant with ISO standards, GMP regulations, and industry-specific cleanliness requirements.
Product Integrity and Safety:
Consistent airflow and air changes are essential for protecting sensitive materials and ensuring that products meet high-quality standards.
Contact Me for HVAC and ACH Guidance
HVAC design and ACH calculations are critical components of cleanroom planning.
If you need assistance with selecting the right HVAC system for your cleanroom or determining the appropriate ACH rates based on your specific industry, I am here to help.
I can guide you through the process to ensure your cleanroom maintains the proper air purity levels and meets all necessary regulatory requirements.
Contact me today to discuss how I can assist with HVAC and ACH considerations for your cleanroom design!