Presence Sensor

Model 873-c

The 873-d Presence Sensor is a must-have for any Fume Hood. Its ability to sense both fast and slow rates of motion allow the sensor to have extremely low chance of false activation.


The Waddell Motion Detector will sense two levels of motion -- a fast rate (person walking to or from the hood) and a slow rate (person working in front of the hood). The motion of a technician is detected by the sensor and is transmitted to the hood controller. The hood controller then selects either an occupied (High) flow rate valve position or an unoccupied energy saving (Low) flow rate valve position.



The motion detector operation is based on a Doppler comparison between the transmitted and received frequencies of the short range K Band radar waves. Only motion is detected – the presence of a non moving device, such as an instrument table, is not recognized. No periodic re-mapping is required to identify a non moving object. Neither a variation in lighting levels or clothing color will affect motion detection.


Applications and Benefits



  • Research Laboratories

  • Teaching Laboratories

  • Quality Control Laboratories



  • Energy Saving

  • Technician Safety

  • Proven Technology

  • Cost Effective



873-c Product Bulletin