LABORATORY EXHAUST FANS CONTROLS - VARIABLE GEOMETRY NOZZLE

The Variable Geometry Nozzle (VGN) automatically adjusts to maintain the specified discharge velocity as lab airflow varies. This safely prevents re-entrainment in the make-up air unit and provides energy savings through lower fan speeds in reduced lab flow situations without introducing bypass air to maintain outlet velocities.

The VGN controller receives a signal from the factory provided pressure transducer and converts that signal into a fan flow. It then calculates the appropriate nozzle opening and sends a signal to the nozzle to adjust it to the proper size opening to maintain desired nozzle outlet velocity. Feedback signal provides BMS details as fan flow, nozzle position and a system alarm. The VGN controller does not signal operation of the fan speed, isolation or bypass dampers and it does not control duct pressure; those parameters are controlled by the BMS.

This control system is suitable for the following options and configurations:

Vektor models MS, CS

Controller for one or more fans (maximum of four)

Adjusts individual fan outlet area to maintain discharge velocity

Outlet velocity is a read/write parameter allowing on the fly adjustments based on outside parameters such as wind speed, chemical concentration levels or laboratory air flows.

Communication with BMS through analog connections