The room pressurization is constantly kept negative with respect to adjoining areas by maintaining the offset air volume ,the difference between the total exhaust air volume and the supply air volume. The airflow control valve (Accel II) ensures highly precise, rapid responses.
Controlling the offset air volume resolve the following problems of differential pressure control systems.
| 1) |
The response time is slower at the time of pressure fluctuations incident to changes in exhaust volumes, for valves are controlled responding to differential pressure feedback signals.
> Solution: Feedforward control based on a constant offset air volume |
| 2) |
As the system is subject to fluctuations in static pressures in the ducts caused by actuation of local exhaust systems and/or disturbances due to door closing and opening or other factors, condition of the air in the adjacent hoods, the next rooms, and even the whole system can be affected.
> Solution: Pressure independence of airflow control valves (Accel II) and room-by-room volume control |
| 3) |
The response time of airflow control valves is slow.
> Solution: Rapid response of airflow control valves (Accel II) in one second or less |
Movie - A test for prevention of cross-contamination
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flash movie - Room pressurization control
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