Dwyer DS-300 Series In-Line Flow Sensor, 1" Probe Length Use with the Dwyer Differential Pressure Gages or Transmitters Pitot tubes have been used in flow measurement for years Conventional Pitot tubes sense velocity pressure at only one point in the flowing stream Therefore, a series of measurements must be taken across the stream to obtain a meaningful average flow rate The Dwyer flow sensor eliminates the need for "traversing" the flowing stream because of its multiple sensing points and built-in averaging capability.