Pneumatic Piezometers
Applications include:
- Monitoring pore pressures to determine safe rates of fill or excavation.
- Monitoring pore water pressures to determine slope stability.
- Monitoring the effects of dewatering systems used for excavations.
- Monitoring the effects of ground improvement systems such as vertical drains and sand drains.
- Monitoring pore water pressures to check the performance of earth-fill dams and embankments.
- Monitoring pore water pressures to check containment systems at landfills and tailings dams.
Please refer to the ordering information tab below before making your selection.
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Piezometer Only
| Description | Part Number |
|---|---|
| Pneumatic Piezometer | 51417800* |
*This part number includes piezometer and one quick connect plug. Tubing is attached to the piezometer at the factory and must be ordered at the same time as the piezometer.
Piezometer with Tubing
| Description | Part Number |
| Piezometer & 50’ of tubing | 51417801 |
| Piezometer & 100’ of tubing | 51417802 |
| Piezometer & 150’ of tubing | 51417803 |
| Piezometer & 200’ of tubing | 51417804 |
Tubing & Connectors
| Description | Part Number |
|---|---|
| Twin Tubing – Two polyethylene tubes bundled in polyethylene jacket | 51416900 |
Installation Accessories
| Description | Part Number |
| Small Canvas Bag 64 x 457 mm (2.5 x 18″) | 06240000 |
| Large Canvas Bag 114 x 457 mm (4.5 x 18″) | 06240001 |
| Push-In Well Point – Steel well point for piezometer, 30 x 610 mm (1.25 x 24″), 2 kg (4.4 lb.). | 51400099** |
**This part number includes labor to insert the piezometer into a good point but does not include piezometer, tubing, or quick-connect plug.
Terminals
| Description | Part Number |
| Terminal Pipe, 6 Positions Heavy gauge, zinc-plated, iridium treated steel pipe, 70 mm x 2 m (2.75″x 80″). | 51409900 The inside panel accommodates quick-connect plugs from 6 piezometers. Includes panel, panel nuts, locking cap, keyed-alike padlock, and 90° PVC sweep for tubing entry |
| Terminal Pipe, 20 Positions Heavy gauge, zinc plated steel pipe, 127 mm x 178 mm x 1.8 m (5″x 7″x 6’). | 51417100 The inside panel accommodates quick-connect plugs from 20 piezometers. Includes panel and panel nuts, locking cap, keyed-alike padlock, and 90° PVC sweep for tubing entry |
| Terminal Box, 10 Positions Fiberglass box with lockable lid, 292 x 235 x 140 mm (11.5 X 9.25 x 5.5″). | 51401510 The inside panel accommodates quick-connect fittings from 10 piezometers. Box can be mounted to a wall or post. Includes panel and panel nuts |
Pneumatic Indicator
| Description | Part Number |
| With 0.25% Analog Gauge | 51425601 |
| With 0.1% Digital Gauge | 51425602 |
| PNEUMATIC PIEZOMETER | |
|---|---|
| Sensor Type | Twin-tube pneumatic transducer |
| Range | Pressure rated for 27.5 bar or 400 psi. The working range depends on the gauge supplied with a pneumatic indicator. The digital gauge provides a range of 690 kPa / 100 psi. Analog gauges provide ranges to 1000 kPa / 150 psi |
| Repeatability | ±0.25% FS |
| Diaphragm Displacement | 0.01 ml typical |
| Filter | Sintered stainless steel, 50-micron pores |
| Materials | ABS and PVC plastic body, synthetic rubber diaphragm |
| Diameter | 25.4 mm (1″) |
| TUBING & CONNECTORS | ||
|---|---|---|
| Twin Tubing | 51416900 | Two polyethylene tubes bundled in polyethylene jacket |
| Tubing Size | 4.76 mm with 1 mm wall (3/16″with 0.04″ wall) | |
| Jacket | 12 mm x 7 mm with 1.1 mm wall (0.46″ x 0.28″ with 0.045″ wall) | |
| Burst Pressure | 3.4 MPa (500 psi) | |
| Minimum Bending Radius | 75 mm (3″) | |
| Tubing Buoyancy | 0.021 kg per m (0.014 lb per foot) | |
| Weight | 0.06 kg per meter (0.04 lb per foot) | |
| Splice Kit | 51401723 | Includes 3 brass unions, self-vulcanizing mastic pad, and sealing tape |
| Quick Connect Plug | 51407302 | Brass quick-connect fitting for input tube. The plug includes an in-line filter and a 90° elbow for insertion into the panel. One quick connect plug included with sensor |
In a typical installation, the piezometer is sealed in a borehole, embedded in fill, or suspended in a standpipe. Twin pneumatic tubes run from the piezometer to a terminal at the surface. Readings are obtained with a pneumatic indicator.
The piezometer contains a flexible diaphragm. Water pressure acts on one side of the diaphragm and gas pressure acts on the other. When a reading is required, a pneumatic indicator is connected to the terminal or directly to the tubing. Compressed nitrogen gas from the indicator flows down the input tube to increase gas pressure on the diaphragm.
When gas pressure exceeds water pressure, the diaphragm is forced away from the vent tube, allowing excess gas to escape via the vent tube. When the return flow of gas is detected at the surface, the gas supply is shut off.
Gas pressure in the piezometer decreases until water pressure forces the diaphragm to its original position, preventing further escape of gas through the vent tube. At this point, gas pressure equals water pressure, and the pneumatic indicator shows the reading on its pressure gauge.
