Modern lab ventilation does more than just control temperature. It must manage airflow intelligently, ensuring the safe removal of contaminants while maintaining clean and stable indoor conditions. A Variable Air Volume (VAV) system makes this possible, and its precise operation relies on two key components: two different types of VAV dampers working in perfect harmony.
Together, they form the essential foundation for safe and efficient laboratory ventilation.
Fume Cupboard Dampers: Protection at the Source
These dampers act as the dedicated controller for each individual fume cupboard.
- What they do:
- They precisely regulate the exhaust airflow from a single fume cupboard in real-time.
- Their primary job is to maintain a constant, safe face velocity (typically 0.3-0.5 m/s) at the cupboard opening, no matter the sash position. This immediate capture prevents harmful fumes from escaping into the lab.
- How they work:
- Connected to sash sensors, they form a fast-response loop. Open the sash, and the damper opens to increase flow. Close the sash, and it closes to reduce flow – all within seconds.
- Built to handle chemicals, they are typically constructed from corrosion-resistant materials like stainless steel.
Room Pressure Control Dampers: Safeguarding the Entire Space
These dampers manage the air supplied to the entire lab room, protecting the surrounding environment.
- What they do:
- They adjust the total volume of fresh air entering the lab.
- Their critical role is to maintain a stable pressure relationship (usually negative pressure) between the lab and adjacent areas like hallways by ensuring supply airflow is slightly less than total exhaust airflow.
- How they work:
- The control system calculates the real-time total exhaust from all hoods and vents. It then directs this damper to provide just enough supply air to maintain the preset pressure differential.
- This constant negative pressure acts as a barrier, ensuring air flows from clean areas into the lab and is exhausted safely, preventing the spread of contaminants.
How They Work Together:
These two types of dampers work in concert with the control system and sensors according to the following logic:
- When a lab technician opens a fume cupboard sash, the exhaust damper for that specific cupboard immediately increases its opening to boost exhaust airflow, maintaining the set face velocity.
- The system detects the increase in the laboratory’s total exhaust volume and, according to preset logic, adjusts the room supply air damper to appropriately increase the fresh air supply.
- Throughout this process, the control system consistently ensures that the supply air volume remains slightly lower than the total exhaust volume. This steadily maintains the required negative pressure state in the room, effectively preventing the escape of contaminants.
Choosing the right VAV dampers for these roles is fundamental to protecting your people, your research, and your facility’s operational efficiency. It’s a smart investment in a safer, more sustainable lab environment.
Click here to explore more about Halton’s airflow management dampers and controllers.
