Operating Principle
Our piezometers are composed by a stainless steel body with calibrated membrane to which the vibrating wire transducer is connected. Pressure causes deformation of the membrane with a corresponding variation in stress on the vibrating wire.
The change in in tension of the wire causes a variation of vibration frequency of the vibrating wire, the square of vibration frequency being directly proportional to the pressure applied to the membrane.
A dedicated excitation group, composed by two coils positioned on an electromagnet, enables the generation of a pulse for vibration of the wire and, at the same time, constitutes the primary element detecting the vibration frequency of the wire.
The connection of the instrument to junction boxes is possible with 2x1smm cable for the measurement of pressure or by 3x1smm or 4x1smm cable for the measurement of pressure and temperature .
The section of the conductors is established according to distance from the final measuring point; we suggest, however, a rubber insulated cable with thick insulation, external diameter 11mm, suitable for direct embedding in concrete and embankments; the suggested section for the conductors is 1mm2.
The cable is locked and protected by a tube with reduced diameter and connected to the instrument body , externally to the metal/glass element of the sealing element.
Additionally it is sealed with resin and a metallic cable gland.
This kind of vibrating wire instruments can be read by our portable readout units DEC5 and DEC3000 or by our automatic acquisition system DAC3000.
Each instrument can be tested and calibrated on a control bench and provided with a calibration certificate complete with gauge factor and zero value taken in our laboratory.
The membrane is protected by a bronze or sintered steel filter, with permeability of 10 μ or 30 μ depending on application. The instrument is equipped with calibrated coil for the measurement of temperature.
As an alternative and on specific request, it can be complete with internal thermistor.
Technical Features
Vibrating Wire Piezometer
| Technology |
Vibrating Wire |
| Range (kg/cmq) |
3 or 5 or 10 or 15 or 20 or 30 (other ranges upon request) |
| Sensitivity |
0,02% f.s. |
| Accuracy |
<0,1% f.s. |
| Resolution |
0,02% f.s. |
| Linearity |
<0,4% f.s. |
| Operation Range (Hz) |
500 – 1200 |
| Drift in temperature |
0,025% f.s. for °C |
| Filter |
In bronze or sintered steel, porosity 10μm or 30μm |
| Material |
Stainless steel AISI 304 |
| Dimensions |
35mm x 110mm |
| Weight |
750 gr |
| Membrane sealing |
Electrowelding TIG |
| Cable sealing |
By weld metal glass, resin and cable sleeve |
Signal Cable
| Type |
Rubber insulated 2×1 mm2; 3x1mm2 |
| Outside diameter |
11mm |
| Maximum allowable traction |
15 N/mm2 movable installations; 50 N/mm2 fixed installation |
| Weight for 100m |
3x1mm2: 18Kg
2x1mm2: 16kg |
Accessories and related products
| Junction Box |
Available in different models for the connection of different instruments |
| Selection and Measurement Box |
Complete measurement box with MUX cards for the automatic selection |
| Measurement Box |
Simple measurement box |
| Cable 2 x 1 or 3 x 1 mm2 |
Special cable insulated in santoprene for the piezometer connection (simple or with temperature measurement) |
| Multipolar cable |
Available with different conductors to connect different sensors to one cable |
| DEC5 |
Portable Readout Unit |
| DEC3000 |
Portable Datalogger |
| CUM3000 |
Multichannel – Datalogger |
| MUX |
Multiplexer for the connection of different sensors |
Technical Assistance
If you have any requests or questions about our instruments or if you have special needs that require different solutions from the standard, please contact us. Our team will provide all the necessary information and will be very happy to work with you to study, develop and customize instruments and solutions suitable for your specific needs.
All information in our datasheet is subject to change without prior notice.
Please check the datasheet/details carefully and contact Pizzi Instruments for further information.
