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1. GENERAL DESCRIPTION
The 4650 Settlement System is designed to measure the differential settlement between two
points. A reservoir is located at a stable reference point and is connected to a sensor located at
the settlement point by two liquid filled tubes. The sensor senses the pressure of liquid within the
tube. This provides a measure of the height of the liquid column, which in turn gives a
measurement of the elevation difference between the reservoir and the sensor.
Figure 1 shows a typical installation used to measure the settlement inside an embankment. The
sensor is read by means of an electrical cable extending to the readout location. Readings may be
taken using a readout box or datalogger.
Figure 1 - Typical Installation of Vibration Wire Settlement System
The sensor (Figure 2) contains a thermistor for measurement of temperature as well as gas
discharge tubes for protection against lightning damage. The cable contains a vent tube that
connects the air inside the sensor to the space above the reservoir. This ensures that the sensor
readings are unaffected by any changes in barometric pressure. A desiccant chamber located at
the reservoir end of the vent line prevents moisture from migrating into the line.
Figure 2 - Sensor Details
