Vibrating Wire Piezometers
Vibrating wire piezometers are used to measure pore-water pressure and water levels. Datasheet
Applications
Typical applications include:
- Monitoring pore-water pressures to evaluate slope stability.
- Monitoring dewatering systems and wick drains at construction sites.
- Monitoring pore pressures to check the performance of earth fill dams.
- Monitoring containment systems at landfills and tailings dams.
- Monitoring water levels in stilling basins and monitoring wells.
Vibrating Wire Piezometer Photo courtesy of Geokon Inc
Operation
The vibrating wire transducer inside the piezometer converts water pressure to a frequency signal via a diaphragm, a tensioned steel wire, and an electromagnetic coil.
The transducer is constructed so that a change in water pressure on the diaphragm causes a change in the tension of the wire. The electromagnetic coil excites the wire, which vibrates at its resonant frequency. The coil then acts as a pickup, senses the frequency of vibration, and transmits a signal readout device.
The readout or data logger then converts the frequency signal to a pressure in engineering units by applying calibration factors.
Advantages
Groutable: VW piezometers can be installed in boreholes that are backfilled with a bentonite- cement grout. This technique makes it possible to install multiple piezometers at different elevations in the same borehole.
High Resolution: VW piezometers provide a resolution of 0.025% FS.
High Accuracy: Most ranges provide an accuracy of ±0.1% F.S.
Rapid Response: VW piezometers respond very quickly to even small changes in pore- water pressure.
Reliable Signal Transmission: Signals from the VW piezometer can be transmitted long distances
Compatible: VW piezometers are compatible with loggers such as the Campbell CR6 or GeoCloud Vibrating Wire Nodes.
Specifications
Sensor Type: Pluck-type vibrating wire sensor with built-in thermistor and tripolar plasma surge arrestors.
Range: Standard ranges include 50, 100, 250, and 500 psi. Custom calibration ranges are available.
Resolution: 0.025% F.S. with suitable readouts.
Accuracy: ±0.1% F.S.
Linearity: <0.5 % F.S.
Materials: Stainless steel wetted surfaces, including the sintered steel filter.
Length x Diameter: 5.2 x 0.75 inch.
Signal Cable: Four conductor cable attached at factory. Vented cable available on request.
Standard Wire Colors
- VW sensor: Red / Black
- Temp sensor: Green / White