| 摘要 |
<p>A fume hood exhaust terminal for monitoring and controlling gas flow in a duct system includes a tubular duct segment having an upstream end, a downstream end, and an inner periphery, as well as an annular ring secured to the inner periphery between the upstream and downstream ends. A differential pressure transmitter device is disposed on the duct segment for measuring the pressure differential across the ring and for generating a corresponding flow signal. A damper is disposed in the duct segment between the differential pressure measuring device and the downstream end, and an actuator is located on the duct segment to be responsive to the signal generated by the differential pressure transmitter device and connected to the damper for selectively controlling the position of the damper in the duct segment to maintain a specified gas flow.</p> |
