Operation

The VW standard borehole piezometer converts water pressure to a frequency signal via a diaphragm, a tensioned steel wire, and an electromagnetic coil. The piezometer is designed so that a change in pressure on the diaphragm causes a change in tension of the wire. When excited by the electromagnetic coil, the wire vibrates at its natural frequency. The vibration of the wire in the proximity of the coil generates a frequency signal that is transmitted to the readout device. The readout device processes the signal, applies calibration factors, and displays a reading in the required engineering unit.

Advantages of Vibrating Wire Piezometers

High Resolution: VW piezometers provide a resolution of 0.025% of full scale.

High Accuracy: Slope Indicator's automated, precision calibration system ensures that all VW piezometers meet or exceed their accuracy specifications.

Groutable: The VW piezometer can be directly grouted-in with a bentonite-cement grout. More information about the direct grout-in method can be found in the VW piezometer manual and in a technical note.

Rapid Response: VW piezometers offer rapid response to changes in pore water pressure, whether they are grouted in, pushed into cohesive soils, or embedded in a sand filter zone.

Reliable Signal Transmission: With properly shielded cable, signals from the VW piezometer can be transmitted long distances.

Temperature Measurement: All VW piezometers are equipped with a temperature sensor.

For more information

Please download the datasheet and manual for the VW Piezometer. These documents can be viewed and printed with Adobe Acrobat Reader. For more information about fully-grouted piezometers, please visit our Papers and References page.

Standard Borehole Piezometer Specifications

STANDARD VW PIEZOMETERS
3.5 bar (50 psi) Piezometer	52611020
7 bar (100 psi) Piezometer	52611030
10 bar (150 psi) Piezometer	52611060
17 bar (250 psi) Piezometer	52611040
35 bar (500 psi) Piezometer	52611050
Signal Cable	50613824

VW PIEZOMETERS WITH CABLE
Standard VW Piezometers, 3.5 bar (50 psi)	with 15 m (50') cable	52611028
	with 30 m (100') cable	52611024
	with 45 m (150') cable	52611027
	with 60 m (200') cable	52611026
Standard VW Piezometers, 7 bar (100 psi)	with 30 m (100') cable	52611033
	with 45 m (150') cable	52611034
	with 60 m (200') cable	52611035
	with 90 m (300') cable	52611036

VW Piezometer Specifications

VW PIEZOMETER SPECIFICATIONS
Sensor Type	Pluck-type vibrating wire sensor with built-in thermistor
Range	Standard ranges are listed at left. Custom calibration ranges are available
Resolution	0.025%FS
Accuracy	±0.1% FS for 0.7 - 7 bar sensors, ±0.3% FS for 17 and 35 bar sensors
Maximum Pressure	1.5 x rated range
Filter	50-micron, sintered stainless steel. A ceramic 1-bar high-air entry filter can be ordered for standard and heavy-duty piezometers by specifying part number 60101240 in addition to the piezometer part number
Temperature Coefficient	< 0.04% FS per °C
Materials	Stainless steel
Size	Standard: 19 x 195 mm (0.75 x 7.75") Low-Pressure: 29 x 191 mm (1.125 x 7.5"). Heavy-Duty: 29 x 191 mm (1.125 x 7.5"). Push-In: 35 x 270 mm (1.385 x 10.5")
Weight	Standard: 0.16 kg (0.3 lb). Low-pressure: 0.45 kg (1 lb). Heavy-Duty: 0.8 kg (1.75 lb). Push-in: 1.2 kg (2.75 lb).

SIGNAL CABLE SPECIFICATIONS
Signal Cable	50613824	Shielded cable with four 22-gauge tinned-copper conductors and polyvinyl chloride (PVC) jacket
Armored Signal Cable	50613586	Shield cable with four 22-gauge tinned-copperconductors, inner polyurethane jacket, steel braid armor, and outer high-density, polyethylene jacket. For heavy duty piezometer only

READOUT & TERMINAL BOXES
VW Data Recorder	52613500
Jumper Cable for Terminal Box	52613557
Terminal Box for 6 sensors	57711606
Terminal Box for 12 Sensors	57711600
Terminal Box for 24 Sensors	97711624