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.
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.
The VW crackmeter provides a repeatability of 0.3 mm.
The VW crackmeter is available in 60 and 100 mm ranges (2.4 and 4 inch).
The VW crackmeter is equipped with a temperature sensor.
The crackmeter connects easily to a data logger for unattended monitoring.
For more information
VW Crackmeter Specifications
|VW CRACKMETER KITS|
|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|
|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||50613824||Shielded cable with four 22-gauge tinned copper conductors and polyvinyl chloride (PVC) jacket. Specify cable length for each sensor.|
|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 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").|
|Compatible readouts include the VW Data Recorder and other pluck-type VW readouts. See separate data sheets for details.|
|VW MiniLogger for 1 Sensor||52613310|
|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|
|Sensor Type||Vibrating wire. A built-in thermistor provides temperature measurements|
|Thermistor||3k Ohms at 25 °C|
|Over-Range||Range + 20%|
|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|