Air volume flow
tracking

Air flow tracking calculates flow setpoints for supply and extract terminals in a room to accomplish pressurization. The difference between supply and extract flows is a fixed, configured value. The setpoints are selected to accomplish heating, cooling, and ventilation within the constraints of the minimum and maximum flow rates for the terminals.

Air flow balances room flows that are under its control (typically supply and extract terminals) and exhaust flows that are independent (for example, fume hoods).

  • Airflow coordination for pressurized rooms, including:
    • Single tracking pair (one supply, one extract)
    • Lab room with fume hood (one supply, one extract, and fume hood exhaust)
    • Large lab with fume hoods (multiple supply, extract and fume hoods)
  • Coordination of airflow demands for heating, cooling, and ventilation
  • Airflow monitoring and alarm values
  • Multiple segment support
    (A segment can include any of the following: supply terminal / extract terminal / supply + extract pair / independent exhaust terminal - fume hood).

Description

Name

Default value

Room pressurization mode

▶ Set the direction of pressurization for the room, and the direction of net air transfer between the room and surrounding spaces.

1:Neutral
▶ Supply flow and exhaust are equal. Contamination is not controlled. Alarm is disabled.
2:Positive pressure
▶ Supply flow is more than extract. Used to keep contaminants out of the room.
3:Negative pressure
▶ Extract flow is more than supply. Used to contain contaminants in the room.

PRMod

1:Neutral

Tracking mode

▶ Select the flow tracking algorithm according to project specifications. If it is not specified, select according to PRMod.

1:Supply air tracks extract air
▶ Typically chosen for negatively pressurized rooms. Controller calculates exhaust flow setpoint from room demands and calculates supply flow setpoint from exhaust.
2:Extract air tracks supply air
▶ Typically chosen for positively pressurized rooms. Controller calculates supply flow setpoint from room demands and calculates exhaust flow setpoint from supply.

TckMod

1:Supply air tracks extract air

Transferred air volume flow setpoint

▶ Controller maintains this value as the difference between supply and extract flow. Set as a positive number.

SpAirFlTrn

10 [m3/h]

For example: In a room with negative pressure, the extract air volume setpoint is = 600, for supply air = 500 and SpAirFlTrn = 100.
In a room with positive pressure, the extract air volume setpoint is = 600, for supply air = 700 and AirFlTrn = 100.

Differential pressure flow cascade control

The differential pressure air volume flow cascade calculates flow setpoints for supply and extract terminals in a room to accomplish pressurization. The difference between supply and extract flows is dynamically adjusted to drive measured room pressure to its configured setpoint. The setpoints are selected to accomplish heating, cooling, and ventilation within constraints of the minimum and maximum flow rates for the terminals.

Room pressure PID adjusts the transfer airflow to drive the measured pressure to the setpoint. The range of adjustment for transfer airflow is set by two configuration value objects, minimum transferred air volume flow and maximum transferred air volume flow.