Piezometer For Data Connectivity

Piezometer (Fig. 1.24) is used to measure underground water pressure. It converts water pressure to a frequency signal via a diaphragm and a tensioned steel wire. A change in pressure on the diaphragm causes a change in tension of the wire. When excited by a magnetic coil, the wire vibrates at its natural frequency. The vibration of the wire in the proximity of the magnetic coil generates a frequency signal that is transmitted to the readout device. The readout device processes the signal and displays a reading. Calibration factors, which establish a relationship between pressure applied to the diaphragm and the frequency signal returned to the readout device, are used to convert Hertz readings to voltage. Piezometer is put into a borehole, sometimes after tying to a grout pipe, and the entire borehole is backfilled with a non shrinking and low permeability grout. Specifications of piezometer are given in Table 1.8.