Vibrating Wire Piezometer

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The RST Vibrating Wire Piezometer provides excellent long-term accuracy, stability of readings and reliability under demanding geotechnical conditions.

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Overview

The RST Vibrating Wire Piezometer provides excellent long-term accuracy, stability of readings, and reliability under demanding geotechnical conditions. Vibrating Wire Piezometers are the electrical piezometers of choice as the frequency output of VW devices is immune to external electrical noise and able to tolerate wet wiring common in geotechnical applications.

Vibrating Wire Piezometers contain a high tensile steel wire with a fixed anchor at one end and are attached to a diaphragm in contact with water pressure at the other end. The wire is electrically plucked, with the resonant frequency of vibration proportional to the tension in the wire. This frequency induces an alternating current in a coil which is detected by the readout unit, such as the VW2106 Vibrating Wire Readout, and can then be converted to a pressure. The frequency output is immune to external electrical noise.

The frequency signal is exceptionally immune from cable effects, including length (to several kilometers), splicing, resistance, noise pickup, and moisture. The vibrating wire coil circuit contains no semiconductor devices and has built-in ionized gas discharge device protection against transient damage. As a result, the vibrating wire piezometer provides excellent reliability in typical geotechnical situations – i.e. long outdoor cables buried in saturated soil.

The piezometer is equipped with a standard sintered stainless steel porous filter to prevent soil particles from contacting the diaphragm. A thermistor is built into the piezometer body to permit temperature measurement and temperature compensation of the piezometer. Standard construction is all stainless steel. RST vibrating wire piezometers are shipped with extremely tough polyurethane-jacketed foil-shielded cable for maximum endurance in field conditions.


Vibrating Wire Piezometer Specifications

ITEM SPECIFICATION
Over range 2 X F.S.
Resolution 0.025% F.S. minimum
Accuracy 0.1% F.S.
Linearity <0.5% F.S.
Operating Temperature -20 to 80°C (-4 to 176°F)
Diaphragm Displacement <0.001 cc at F.S.
Thermal Zero Shift <0.05% F.S./°C
Materials Hermetically sealed stainless steel housing
Thermistor Type NTC 3K Ohms @ 25°C
Thermistor Interchangeability ±0.2°C
Thermistor Resolution 0.1°C
Filter 50 micron sintered filter. (High air entry alumina filter 1 Bar available)


Electrical Cable Specifications

PART # DESCRIPTION
EL380004 Two twisted pairs cable with polyurethane jacket
EL380004HDL Two twisted pairs heavy-duty cable with a thick polyurethane jacket mold for added protection
EL380004K Two twisted pairs Kevlar® reinforced, non-stretch polyurethane jacketed cable for rigorous installations where the stretching of cable is a concern

*Other types of cables, depending on site conditions and atmospheric reference requirements, are available upon request. These include vented, FEP, PVC, polyurethane, and armored varieties.

Vibrating Wire Piezometers are commonly used for:

  • Assessing performance and investigating stability of earth fill dams and embankments.
  • Slope stability investigations.
  • Monitoring water levels in wells and standpipes.
  • Monitoring pressures behind retaining walls and diaphragm walls.
  • Monitoring pore pressures during fill or excavation.
  • Monitoring pore pressure in land reclamation applications.

View illustrations on how Vibrating Wire Piezometers are used for:

Vibrating Wire Piezometer Ordering Info

PART # DESCRIPTION PRESSURE RANGE DIMENSION
VW2100 Standard model for general applications 0.35, 0.7, 1.0, 2.0, 3.0 MPa 19 mm Ø X 130 mm
VW2100-HD Heavy duty piezometer for direct burial in fills and large dam embankments or for high pressure borehole installations 0.35, 0.7, 1.0, 2.0 3.0, 5.0, 7.5, 10, 20 MPa 25.4 mm Ø X 146 mm
VW2100-DPC Drive point model with CPT thread 0.07, 0.175, 0.35, 0.7, 1.0, 2.0, 3.0, 5.0, 7.5 MPa 33.4 mm Ø X 508 mm
VW2100-DPEW Drive point model with EW thread 0.07, 0.175, 0.35, 0.7, 1.0, 2.0, 3.0, 5.0, 7.5 MPa 34.6 mm Ø (body) X 304.8 mm
VW2100-L Low Pressure, unvented 70, 175 kPa 25 mm Ø X 133 mm
VW2100-LV Low Pressure vented 70, 175 kPa 25 mm Ø X 133 mm
VW2100-M Miniature version – 17.5 mm diameter 0.35, 0.7, 1.0, 2.0, 3.0 MPa 17.5 mm Ø X 133 mm
VW2100-MM Micro-miniature version – 11.1 mm diameter 0.35, 0.7 MPa 11.1 mm Ø X 165 mm
VW2190 Heavy duty piezometer with bladder for brine environment 0.07, 0.175, 0.35, 0.7, 1.0, 2.0, 3.0, 5.0, 7.5 MPa 42 mm Ø X 319 mm
VW2191 Heavy duty piezometer with bladder for acidic environment with secondary corrosion protection 0.07, 0.175, 0.35, 0.7, 1.0, 2.0, 3.0, 5.0, 7.5 MPa 42 mm Ø X 319 mm

 

Optional Equipment

VW2106 Vibrating Wire Readout
Data loggers
Cable splice kits

File Name

Vibrating Wire Piezometer

Resource Type

Brochure
Language Version Download
English ELB0055O
Portugese VWB0002B
Spanish ELB0069F

File Name

Vibrating Wire Piezometer Manual

Resource Type

Manual
Language Version Download
English ELM0005T

Speak with an Expert

I’m very happy with the quality of the instrumentation and technical support from RST, as always. They worked with us from the initial stages of the project to ensure that we were fully prepared and equipped to use the RSTAR network for the first time. They delivered everything within the tight project time frame to ensure that there were no delays on site, and the submersible tilt meters looked like new even after over twelve months of being submerged in Thames water!
 
-Richard Lipscombe, BEng (Hons), Director & Principle Consultant - RL Geotechnical Ltd