There are different types of Audible/Visual (AV) indicator systems used on fume hoods at Carleton University. Your fume hood might have one of the indicators listed below. These indicators have an audio and/or visual indicator which alerts laboratory personnel if there is insufficient airflow in the fume hood or laboratory ventilation equipment.

There are four different indicators installed on fume hoods around campus:

  • Active Devices
    • Plastec, Alnor,  Landis & Gyr and Phoenix Face Velocity Monitors:
      • Face velocity indicator with an audible and/or visual alarm if the face velocity goes below or exceeds a safe level.
    • Vent Alert Monitors:
      • Air flow indicator with an audible and/ visual alarm if the air flow goes below or exceeds a safe level.
    • Hoffman Air Flow Monitors
      • Green indicator light for normal operation.
      • Red indicator light and audible alarm when the velocity goes below or exceeds a safe level.
  • Passive Devices:
    • Magnehelic:
      • Qualitative flow indicator only. The gauge should read greater than 0.1 inches of water.

When an AV system indicates a problem with the fume hood or ventilation equipment:

  • Stop all processes, close all chemicals bottles and remove to an appropriate storage area.
  • Contact EHS at X3000
  • Do Not simply press the silence button on the AV indicator and continue working. You may expose yourself and others to hazardous chemicals.