Working principle

The VW Piezometer operates on the principle that a tensioned wire, when plucked, vibrates at its resonant frequency. Around the wire is a magnetic coil which when pulsed by a vibrating readout or data logger interface plucks the wire and measures the resultant resonant frequency of vibration. A change in distance between the anchor and the diaphragm is related to pressure differentials and can be converted to a kPa reading.

Temperature information can be used if logging regularly to determine swift temperature changes during which pressure readings may be exaggerated

Features

Reliable long-term performance

R ed, suitable for demanding environments

High accuracy

Insensitive to long cable lengths

All non-drive-in models can have threaded adaptors to customer specifications

Applications

Pore pressure measurement in soils and rocks

Fluid pressures in hydro-fracture and pump tests

Structure

Permeable ring +sensitive membrane+seal case+signal wire+vibration wire+strong vibration eletromagnetic

Caculate

When pore piezometer loads pressure of water, the voltage "P" and output frequency "F" as below : 

P = k（F20-F2i）

K — Pressure Sensitivity

Fi — Measurement

F0— Reference Value