Pointing to a row of circular icons featuring wind turbines, with one red icon showing an air conditioning unit.
Clean rooms are essential in various industries, including pharmaceuticals, biotechnology, and electronics manufacturing. They ensure that critical processes occur in a controlled environment free from contaminants. One of the most crucial aspects of maintaining such an environment is the Air Changes per Hour (ACH), which measures how frequently the air within the clean room is replaced.
Understanding Air Changes per Hour (ACH)
ACH is a critical metric that represents the number of times the air within a room is replaced with fresh, filtered air in one hour. It ensures that any contaminants introduced into the clean room are swiftly removed, maintaining the desired air quality.
The Importance of ACH in Clean Rooms
1. Contaminant Control: Higher ACH rates ensure that contaminants such as dust, microbes, and chemical vapors are quickly removed.
2. Regulatory Compliance: Many industries have strict regulations regarding air quality in clean rooms. Compliance with ACH requirements is often mandated.
3. Product Quality: Maintaining a specified ACH ensures that products manufactured in clean rooms are not compromised by contaminants, leading to higher product quality and safety.
4. Employee Health: Proper ventilation and air changes ensure a healthier working environment, reducing the risk of exposure to harmful substances.
Calculating Air Changes per Hour (ACH)
The formula to calculate ACH is straightforward:
The formula for determining Air Changes per Hour (ACH) involves multiplying the volume of a space by the airflow rate (CFM) and then by 60 to convert minutes to hours.
Where:
- Airflow is the rate of airflow in cubic feet per minute (CFM)
- Volume is the volume of the space in cubic feet
Formula to calculate Air Changes per Hour (ACH), which is the volume of air supplied in Cubic Feet per Minute (CFM) multiplied by 60, divided by the volume of the room in cubic feet.
Where:
CFM = Cubic Feet per Minute of air supplied
Step-by-Step Calculation:
1. Determine the Volume of the Room:
- Measure the length, width, and height of the room.
- Calculate the volume using the formula:
Volume = Length × Width × Height
2. Measure the Air Supply Rate:
- Obtain the CFM from the HVAC system specifications or measure it directly.
3. Apply the Formula:
- Plug the room volume and air supply rate into the ACH formula to get the number of air changes per hour.
Example:
Consider a clean room with the following dimensions:
- Length = 20 feet
- Width = 15 feet
- Height = 10 feet
The volume of the room is:
Volume = 20 × 15 × 10 = 3000 cubic feet
Assume the HVAC system supplies air at a rate of 500 CFM. The ACH would be:
ACH = (500×60)/3000
= 10 Air Changes per Hour.
Implementing ACH in Project Planning
When planning a project involving clean rooms, it's essential to integrate ACH calculations early in the design phase. Here's how:
1. Set ACH Targets:
- Define the required ACH based on industry standards and specific project needs.
2. Design HVAC Systems:
- Ensure the HVAC system is capable of achieving the targeted ACH. This might involve selecting the right filters, fans, and ducting.
3. Regular Monitoring and Maintenance:
- Implement systems to monitor ACH continuously and schedule regular maintenance to ensure consistent performance.
4. Documentation and Compliance:
- Maintain detailed records of ACH calculations, system specifications, and monitoring data to ensure compliance with regulatory requirements.
A technician in a cleanroom of pharmaceutical company monitoring air quality systems,
ensuring optimal air changes per hour (ACH) for contamination control.
Conclusion
Understanding and calculating ACH is fundamental to the successful operation of clean rooms. By ensuring the air within these environments is frequently replaced, you can maintain high standards of cleanliness, comply with regulations, and protect both product quality and employee health.
At BM EPC International, we emphasize the importance of meticulous planning and detailed execution in every project. By integrating ACH calculations into our project plans, we ensure that our clean room projects meet the highest standards of performance and reliability, delivered on-time and on-budget.
For more detailed guidance on integrating ACH into your clean room projects or to learn about our comprehensive project management services, contact BM EPC International today.