Jointmeters and Crackmeters

Vibrating Wire Crackmeter

///Vibrating Wire Crackmeter

Description

The vibrating wire crackmeters are generally used for the automatic measurement of surface cracks in buildings, civil works or historical works, openings in the ground, monitoring of structural joints in dams, bridges or artifacts. They consist of a linear displacement sensor with full vibrating wire technology with two anchors to be fixed to the sides of the crack.
Pizzi Instruments’s crackmeters are developed for different applications and are supplied with different measuring ranges and accessories required for specific applications. Models are available with IP67, IP68 protection or totally watertight with resistance to pressures of up to 100 meters of water column or higher. The vibrating wire crackmeters can be applied on mechanical biaxial or triaxial supports to monitor deformations in 2 or 3 orthogonal directions (2D or 3D control); they can be read manually with our portable units (DEC 3000 and DEC 5) or automatically with our datalogger (CUM3000, VW Brick 2, VW Brick 8, CRio VW). They can be integrated into automatic monitoring systems with real-time monitoring of phenomena and management of local alarms and real time remote alarms.
For specific requests and needs, we develop and manufacture customized products and customized with different characteristics to standard.

Applications

  • Cracks in structures or rock
  • Structural Joints
  • Dams
  • Galleries
  • Rock mass
  • Buildings of reinforced concrete or masonry
  • Monuments and buildings
  • Landslides
  • Immersion
  • Applications at great depths
  • Various

Depending on the specific applications and on the measuring ranges and accuracies , vibrating wire crackmeters are available with different wire deformation amplification systems

Features and Benefits

  • Sturdy
  • Simple installation
  • High resolution and sensitivity
  • Excellent accuracy and linearity
  • High reliability
  • Ideal for long-term monitoring
  • Integrated temperature sensor (optional)
  • Completely stainless steel
  • 3D displacement monitoring accessories

Measurement principle

The body of the instrument is made of two stainless steel tubes of different diameter so that one slides inside the other.
Inside the two cylinders is a harmonic steel wire, the ends of which are connected, through an amplification system, to the head of the two tubes. The sliding of the two tubes causes a lengthening or a shortening of the wire which consequently varies its own frequency of vibration. As the two ends of the instrument are fixed on the two points whose variation in distance is being measured, the elongation of the wire will be proportional to the variation in distance between these points.
The standard version has a degree of protection IP67. A special version , completely sealed and with resistance to 10 atm, is also available.

Technical Features

Technology Vibrating Wire
Sensor of temperature Integrated (if requested)
Range 0÷5mm, 0÷10mm, 0÷25mm, 0÷50 mm, other on request
Accuracy ± 0.2% f.s.
Linearity < ±0,2% f.s.
Resolution < 0,02% f.s.
Frequency Range 500 Hz ÷ 1000 Hz
Material Stainless Steel
Inner Rod Harmonic Steel
Anchoring Types Dowels, threaded bars, fixtures
Protection IP67 or IP68 up to 10 atm
Signal Cable 2 x 0,5; 3 x 0,5 with integrated thermistor
Max Distance to Datalogger 1000 mt

Accessories and Related Products

Triaxial Deformometer Allows the mounting of 3 crackmeters for the monitoring of a crack into the three directions x,y,z,
Fixing Kit Axis Y Allows the monitoring of the crackmeter for the control of the axis Y
Fixing Kit Axis Z Allows the monitoring of the crackmeter for the control of the axis Z
Junction Boxes Different Models for the connection to the different instruments
Multi-core cable Different conductors for the connection of different sensors to one cable
DEC 5 Portable Readout Unit
DEC 3000 Portable Datalogger
CUM 3000 Multichannel Datalogger
MUX Multiplexer for the connection of different sensors to the Datalogger