by Burt Smith, Product Engineer at AJ Manufacturing Co., Inc.
There is a dizzying array of control options and possible control schemes out there for HVAC systems and adding a clean room creates even more complexity. With new requirements like USP 800 firms previously unexposed to these types of systems are now being thrust right into the deep end of complex cleanroom scenarios.
The most difficult situations are those where 100% fresh air is required to the space and you have strict pressure requirements that are significantly different for adjoining rooms. An example of this is a compounding pharmacy which includes exhaust hoods that add to the issues.
Attempting to control incoming and outgoing CFM to maintain the narrow window of pressure requirements is the conventional thinking of balanced system. Balancing a system to achieve this can be very time consuming and there are always unexpected conditions on site that require fine tuning to meet the room requirements further adding to the complexity and frailty of the balance.
There is was to reduce this time consuming process and make the system more robust. Modern controls allow for not just monitoring and controlling to these indirect CFM methods but directly to the requirements themselves.
Modern EC motor fans, like those in our Criti-Clean products, can be directly controlled by a sensor or building management system to maintain the required differential pressures, particle counts, or other critical criteria directly. Using a direct control method often simplifies balancing and ensures that the requirements of the room are more likely to be met even when there is a component failure, inadvertent flow change, or even something as simple as an anteroom door being opened.
Identifying the most critical requirements and prioritizing them will allow you to design a more robust system with better reliability and more useful reporting data. Let us help you ensure your projects success now and in years to come by working with our engineers early in the design process to help find your best solution.