VW Crackmeter

VW Crackmeter

Applications

The VW crackmeter is used to monitor movement at joints and cracks in concrete structures or rock. Typical applications include:

  • Monitoring joints for unexpected movement to provide early warning of performance problems
  • Monitoring joints and cracks in structures that may be affected by nearby excavation and construction activities.
  • Monitoring cracks in structures that have experienced seismic activity.
VW Crackmeter

Operation

The VW crackmeter consists of a VW displacement transducer and a mounting kit. Anchors are installed on opposite sides of the crack and the transducer is mounted across the anchors. A change in the distance across the crack causes a change in the frequency signal produced by the VW displacement transducer when excited by the readout or data logger.

The readout device processes the signal, applies calibration factors, and displays a reading in millimeters or inches. The initial reading is used as a datum. Subsequent readings are compared to the datum to calculate the magnitude, rate, and acceleration of movement across the crack.
 

Advantages

High Accuracy

The VW crackmeter provides a repeatability of 0.3 mm.

Two Ranges

The VW crackmeter is available in 60 and 100 mm ranges (2.4 and 4 inch).

Temperature Measurement

The VW crackmeter is equipped with a temperature sensor.

Manual or Automatic Readings

The crackmeter connects easily to a data logger for unattended monitoring.

For more information

Please download the datasheet and the manual for the VW Crackmeter and the datasheet for the VW Displacement Sensor (Transducer).
These documents can be viewed and printed with Adobe Acrobat Reader.

VW Crackmeter Specifications

VW CRACKMETER KITS
60mm, Splashproof 52636381
60mm, Waterproof 52636388
100mm, Splashproof 52636382
100mm, Waterproof 52636389
The VW Crackmeter consists of two components: a vibrating wire displacement sensor and a set of anchors. Signal cable, ordered separately, is connected to the sensor at the factory.
Sensor Type Vibrating wire. A built-in thermistor
provides temperature measurements.
Range 60 mm or 100 mm
Resolution 0.025% FS with VW Data Recorder
Calibration Accuracy ±0.1% FS
Repeatability ±0.5% FS
Waterproof Rating Waterproof crackmeter is rated to 17 bar (250 psi)
Materials Stainless steel body and shaft, Neoprene O-rings, plated-steel swivels, mild-steel anchors
Nominal Length 60 mm crackmeter is 400 mm (15.7") long; 100 mm crackmeter is 530 mm (21") long
SIGNAL CABLE
Signal Cable 50613824 Shielded cable with four 22-gauge tinned copper conductors and polyvinyl chloride (PVC) jacket. Specify cable length for each sensor.
EXTRA ANCHORS
Anchor Set 52636080 Set of two groutable anchors. Needed if the crackmeter is moved to a new location
Ball Joint 02700196 One ball joint. Needed if either of the original ball joints supplied with the crackmeter are damaged or corroded.
TERMINAL BOXES
Terminal Box for 6 sensors 57711606
Terminal Box for 12 Sensors 57711600
Terminal Box for 24 Sensors 97711624
Provides terminals for signal cable from 6, 12, or 24 sensors. Sensors are selected by rotary switch.Small 6-sensor box is 240 x 190 x 120 mm (9.5 x 7.5 x 4.75"). Larger 12 and 24-sensor box is 290 x 345 x 135 mm (11.5 x 13.5 x 5.25").
READOUTS
Compatible readouts include the VW Data Recorder and other pluck-type VW readouts. See separate data sheets for details.
DATA LOGGERS
VW MiniLogger for 1 Sensor 52613310
4-Channel V-Logger 52615140
Campbell Scientific Data Loggers VW displacement transducers connect directly to the VW MiniLogger, V-Logger and Campbell Scientific CR6. Campbell Scientific CR800 or CR1000 require an AVW200 vibrating wire adapter. See separate data sheets.

VW Displacement Sensor Specifications

VW DISPLACEMENT SENSORS
Range Length Part Number
12.5mm 195mm 92636135
25mm 243mm 92636255
50mm 275mm 92636055
75mm 369mm 92636075
100mm 400mm 92636335
150mm 530mm 92636155
200mm 660mm 92636205
300mm 917mm 92636305
500mm 1433mm 92636505
Sensor Type Vibrating wire. A built-in thermistor provides temperature measurements
Thermistor 3k Ohms at 25 °C
Over-Range Range + 20%
Resolution 0.025% FS
Calibration Accuracy ±0.1% FS
Non linearity <0.5% FS
Frequency Range 1650 - 2700 Hz
Nominal zero value 1850 Hz
Waterproof Rating Waterproof crackmeter is rated to 16 bar (232 psi)
Diameter 12.5mm to 300mm range are 13mm in diameter. 500mm range is 16mm in diameter