Abstract: Energy saving and efficiency structural improvements to venturi valve airflow control device that provides constant-velocity hood intake at all positions of hood access-opening for extended product life through the insertion of a “shock absorbing” device ring that maximizes the efficiency of the floating cone in the venturi valve.

Abstract: A fume hood optical sash sensing system for controlling the flow of air into a fume hood to maintain a constant face velocity by utilizing an optical sensing device mounted inside the fume hood that can sense the movement of a sash based on repeatable reflexive tape to produce an output control signal that corresponds to sash movement to produce desired airflow into the fume hood. The system includes an optical sensing device with a light source, reflexive tape with a repetitive, quadrature encoded pattern, a smart controller device that receives output control signals from the optical sensing device, and an actuation device capable of receiving the output signal from the controlling device to control the damper device that will result in constant face velocity across the face of the sash. Obvious permutations of the above can be adapted for various fume hood sash configurations.