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

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, Splashproof52636381
60mm, Waterproof52636388
100mm, Splashproof52636382
100mm, Waterproof52636389
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 TypeVibrating wire. A built-in thermistor
provides temperature measurements.
Range60 mm or 100 mm
Resolution0.025% FS with VW Data Recorder
Calibration Accuracy±0.1% FS
Repeatability±0.5% FS
Waterproof RatingWaterproof crackmeter is rated to 17 bar (250 psi)
MaterialsStainless steel body and shaft, Neoprene O-rings, plated-steel swivels, mild-steel anchors
Nominal Length60 mm crackmeter is 400 mm (15.7") long; 100 mm crackmeter is 530 mm (21") long
SIGNAL CABLE
Signal Cable50613824Shielded cable with four 22-gauge tinned copper conductors and polyvinyl chloride (PVC) jacket. Specify cable length for each sensor.
EXTRA ANCHORS
Anchor Set52636080Set of two groutable anchors. Needed if the crackmeter is moved to a new location
Ball Joint02700196One ball joint. Needed if either of the original ball joints supplied with the crackmeter are damaged or corroded.
TERMINAL BOXES
Terminal Box for 6 sensors57711606
Terminal Box for 12 Sensors57711600
Terminal Box for 24 Sensors97711624
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 Sensor52613310
4-Channel V-Logger52615140
Campbell Scientific Data LoggersVW 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
RangeLengthPart Number
12.5mm195mm92636135
25mm243mm92636255
50mm275mm92636055
75mm369mm92636075
100mm400mm92636335
150mm530mm92636155
200mm660mm92636205
300mm917mm92636305
500mm1433mm92636505
Sensor TypeVibrating wire. A built-in thermistor provides temperature measurements
Thermistor3k Ohms at 25 °C
Over-RangeRange + 20%
Resolution0.025% FS
Calibration Accuracy±0.1% FS
Non linearity<0.5% FS
Frequency Range1650 - 2700 Hz
Nominal zero value1850 Hz
Waterproof RatingWaterproof crackmeter is rated to 16 bar (232 psi)
Diameter12.5mm to 300mm range are 13mm in diameter. 500mm range is 16mm in diameter