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GEOSTRING – In Place MEMS Inclinometer

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EASY INSTALLATION

VERTICAL STRING OF MEMS SENSOR NODES

LOW COST REAL TIME MONITORING

The GEOSTRING inclinometer is a string of closely spaced MEMS sensors, ideal for real time continuous and unattended monitoring of lateral displacement of soil, rock and structures.

 

Description

The GEOSTRING system consists of a number of sensor nodes in a vertical string installed in either 70mm (2.75-inch) diameter inclinometer casing or in 38mm (1.5-inch) diameter Schedule 40 PVC pipe.

The pipe or casing provides access for subsurface measurements. The joints between each sensor are robust, allowing the system to maintain a consistent orientation of all the nodes, regardless of whether it is installed in ABS inclinometer casing or PVC pipe. 

The pipe or casing is typically installed in a vertical borehole that passes through a suspected zone of movement. The nodes are spaced at 0.61 m (2 ft) intervals and provide a reading resolution similar to a  traversing probe. The system spans the zone of movement occurs, the pipe/casing moves as well, changing the inclination of the nodes inside.

Inclination measurements from the nodes are processed to provide graphs of the casing profile and changes in the profile. Changes indicate displacement (movement).

The system requires casings, GEOSTRING segments, a suspension kit, a bottom plug and a jumper cable. 

Nodes, cables, connectors and gage rods are exceptionally durable, making it practical to remove the systems at the end of the project and redeploy them on other projects.

The GEOSTRING system is connected to a SENSLOG data acquisition system, and readings are transmitted to processing software that can trigger alarms based on displacements or rate of change. 

A number of Campbell Scientific data loggers can be integrated in a Roctest Senslog for GEOSTRING systems.Two GEOSTRING systems can be connected on a CR6 or a CR1000X. With an MD485 module per GEOSTRING system, the CR1000 can read up to five systems, the CR800 three systems and the CR300 one system.

GEOSTRING systems have joints capable of bending to 90°, allowing for a compact shipping option. Five segments, each 3.048 meters (10 feet) long, can be shipped in a carton measuring approximately 64 x 64 x 64 cm (26 x 26 x 26 in) and which weigths less than 22 kilograms (50 pounds). Because of its compact size, the system can be shipped via standard overnight service.

 

Specifications
Sensor type MEMS (Micro Electro-Mechanical Systems) tilt sensors for inclination readings.
Thermistor for temperature readings.
Calibrated Range ±30 degrees from vertical over a temperature range of -10°C to +40°C.
Resolution with SENSLOG 9 arc seconds or 0.04 mm/m using the CR1000 data logger.
Repeatability ±82 arc seconds or ±0.4 mm/m.
Power requirements Minimum supply voltage of 10 Vdc. Maximum supply voltage of 30 Vdc.
Digital RS485 signal requires Campbell Scientific data logger.
Housing Stainless steel, 32 mm diameter, waterproof to 2 MPa
Weight 0.54 kg per 0.6m (1.2 lb per 2 feet) gauge length.
Waterproof Waterproof to 2 MPa (300 psi).
Signal Cable Jumper Cable for connecting the system to the datalogger.
Connectors are rated to 70 MPa (10,000 psi).
Casing 70 mm (2.75 in) diameter casing.
38 mm (1.5 in) Schedule 40 PVC Pipe.
Data Logger Compatible with CR6, CR300, CR800, CR1000 & CR1000X Data Loggers.
MD485 RS-485 Interface required for CR300, CR800 & CR1000 Data Loggers.
Ordering Info
Description Length  Length  Inclinometer Casing System Schedule 40 PVC Pipe System
  (m) (ft) 70 mm (2.75 in)  38 mm (1.5 in) 
GEOSTRING Standard Segment        
5 Sensor GEOSTRING Standard Segment  3.048 10 FR-0387050100 FR-0387050200
GEOSTRING Custom Segments        
4 Sensor GEOSTRING Custom Segment 2.438 8 FR-0387050108 FR-0387050208
3 Sensor GEOSTRING Custom Segment 1.828 6 FR-0387050106 FR-0387050206
2 Sensor GEOSTRING Custom Segment 1.219 4 FR-0387050104 FR-0387050204
1 Sensor GEOSTRING Custom Segment 0.609 2 FR-0387050102 FR-0387050202
GEOSTRING Dummy Segments        
Dummy  GEOSTRING Segment 1.524 5 40-0387040105 40-0387040205
Dummy  GEOSTRING Segment 0.609 2 40-0387040102 40-0387040202
GEOSTRING Required Accessories        
Suspension Kit, GEOSTRING     40-0387040410 40-0387040420
Jumper Cable, GEOSTRING to Logger 50 164 40-0387040350 40-0387040350
Jumper Cable, GEOSTRING to Logger 25 82 40-0387040325 40-0387040325
Bottom Plug, GEOSTRING, 6 Pin Seacon     40-0387040500 40-0387040500
GEOSTRING Replacement Accessories       
Replacement Centralizer     40-0387040610 40-0387040620
GEOSTRING Clevis Pin with Head     40-0387040700 40-0387040700
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