Basic Documentation

Room Pressurization Control Application Guide
• The Makeup Airflow and Exhaust Airflow for each room is individually measured and
controlled by the room controller.
Room Pressurization Control
The Room Controller continuously monitors each room's static pressure level between the
respective room and the Personnel Corridor by means of the Room Static Pressure Sensor.
The room controller modulates the room supply Makeup Airflow to ensure that the laboratory
room is always maintained at its static pressure set point by a Proportional Integral Derivative
(PID) closed loop control algorithm.
The room pressurization control scenario also includes selectable MAXIMUM and MINIMUM
room airflow limits. These airflow limits prevent the room pressurization control strategy from
attempting to increase the room supply makeup airflow above a specific limit or decrease the
room exhaust below a specific limit under transient conditions, such as when a connecting
door is open as indicated by the respective door switch. These limits prevent the control
scenario from attempting to maintain the room static pressure set point by creating an
excessive airflow imbalance.
The room static pressurization control strategy also includes selectable high and low room
static pressure alarm limits and an adjustable Room Static Pressure alarm delay period.
Whenever the room static pressure exceeds a high or low static pressure alarm limit in
excess of the alarm delay period, annunciation of the alarm condition can occur at
designated locations.
In operation, the control sequence first attends to the most critical area and then each
succeeding area of lower pressurization. In other words, the higher the required
pressurization, the higher its control priority will be.
42 Siemens Building Technologies, Inc.