29. Drifting Velocity Sensor

This scattergraph displays data from a flow monitor with a drifting velocity sensor.  Note that the reported flow velocity drifts over a wide range without a corresponding change in depth.  This flow monitor was equipped with an electromagnetic velocity sensor, which is subject to fouling from grease.  The sensor performance worsened over time and eventually caused the flow monitor to report negative velocities.  The data from this flow monitor are invalid and should be disregarded.