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.
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
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
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 | |
