BAC-9311C-AFMS | Controller: KMC Airflow Measurement System, BACnet AAC, Pressure Sensor, Clock, MSTP

The KMC Airflow Measurement System (AFMS) reliably provides accurate outside, return, and supply airflow data for monitoring and control. The system delivers accurate, repeatable results on any type of equipment, without the traditionally expected mechanical limitations, performance issues, or ongoing maintenance issues.

It consists of the following components, installed on an AHU, RTU, or unit ventilator:

• One controller with airflow measurement programming [BAC-9311C(E)-AFMS or BAC-5901C(E)-AFMS]
• One inclinometer (included with the controller) mounted on an outside air damper blade
• At least two pressure flow pickup tubes (SSS-1000 Series) installed on the supply air duct, or on the fan inlet
• If a BAC-5901C(E)-AFMS is used, one pressure transducer (TPE-1475-21)
• If pressure-assist measurements are needed (for units with changing pressure in mixed and/or return air sections), one additional pressure transducer (TPE-1475-21), connected to two additional pressure flow pickup tubes (SSS-1000 Series) mounted on both sides of the outside air damper
• Three temperature sensors (STE-1400 Series) for outside, mixed, and return air
• One proportional actuator mounted on the damper shaft

The system measures outside and return air by characterizing damper performance. A characterization curve allows the controller to determine airflow percentages at each angle of the damper. The system’s programming generates the curve using a Learn Mode sequence, leveraging the relationship between the inclinometer and a mixed air equation. During Learn Mode, the damper is positioned at several known points. At each point, the airflow and outside, return, and mixed air temperatures readings are allowed to stabilize before being sampled and averaged. Thereafter, the sensors are no longer needed to measure the airflow rates, but can be left installed for recalibration and fault-detection purposes.