1.Introduction
The Model 4651 Vibrating Wire Settlement Profiler is shown schematically in Figure 1. It consists of a vibrating wire pressure sensor, a liquid-filled tube mounted on a portable reel, a reservoir with sight tube, and a vented signal cable leading from the sensor to a readout box.
Figure 1: Typical Settlement Profiler Assembly
In use, the reel is mounted on a pedestal located on solid ground, and is free to turn as the sensor and liquid tube is pulled along a buried pipe, or as the sensor is carried from location to location. The sensor accurately measures the height of the liquid column between the sensor and the reservoir at any point along the buried pipe. The liquid-filled tube is graduated in either meters or feet so that the sensor can be located accurately and repeatedly inside the buried pipe.
Provision must be made to enable the sensor to be pulled into the pipe. This will require a pull-in cable passing over a pulley at the far end of the pipe. A retrieval cable can be attached to the back end of the sensor to allow the sensor to be retrieved without pulling on the instrument cable. Four wire rope clamps are included for attaching the retrieval cable to the sensor. Retrieval cable can be purchased from geokon.
The vibrating wire sensor is vented to atmosphere through the signal cable so that it is not affected by barometric pressure fluctuations. A desiccant chamber is mounted on the end of the vent tube to prevent moisture from reaching the sensor.