The ShapeAccelArray Field (SAAF) is a type of SAA that is most commonly used. All SAA types have rigid segments separated by flexible joints. Triaxial MEMS gravity sensors measure tilt in each individual segment. SAAFs produce data equivalent to inclinometer data. Each SAA is a fully-calibrated measuring instrument with a length of up to 100 meters, delivered on a reel, and installable in very small diameter casing. As a result, installation is rapid and lower in cost, and much larger deformations can be monitored.
An SAAF may be installed near vertical to track the magnitude and direction of lateral deformation, or near horizontal to track vertical deformation. It can also be installed along the cross-section of tunnels and used in “mixed H/V” mode to measure convergence. Due to the bandwidth of the MEMS sensors and communication protocol, it is possible to use the SAAF to monitor 3D vibration data at up to three selected locations along the instrument. The SAAF model 003 has a non-multiplexed structure where every segment has a microprocessor unit and a temperature sensor.
SAAV is the newest and most advanced ShapeArray model. Inspired by direct feedback from customers, Measurand developed a new installation method unique to the SAAV that allows the array to be installed easily into existing conventional inclinometer casings.
SAAV’s off-the-reel cyclical installation system inserts the ShapeArray in a zigzag pattern into casings from 47 mm to 100 mm in diameter. The SAAV is then locked into place with a Spring Box assembly. SAAV is ideal for retrofitting ShapeArray instrumentation into existing conventional inclinometer casings or for new installations in ungrooved casings.
SAA installations are designed for either manual or automated measurements with a PC or Data Logger and can be powered with either mains or solar power. Other custom solutions are also available, contact for more details. All communications in the SAA are digital and carried along a cable to the reading device. Standard software required to collect, process, and view SAA data is available free of charge from the Measurand website within the SAASuite software package. A Measurand interface is required between an SAA and logger or computer. Interface functions include protocol conversion, power control, and surge protection. Interfaces include SAA232, SAA Field Unit, and SAAUSB.
Physical Properties:
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Segment length: 305 mm or 500 mm (joint centre to joint centre)
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Maximum length of SAAF: 100 m (500 mm segments) or 60.96 m (305 mm segments)
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Maximum number of segments: 200
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Length of far tip end: 60 mm
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Length of unsensorized near cable end: 340 mm (includes: Cable Terminator Segment underneath PEX)
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Length of hardened cable (inside PEX): 175 mm
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Length of PEX tubing: 1,5 m standard
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Length of communication cable: Standard 15 m (13,5 m extending past the PEX tubing)
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Weight: 0,6 kg/m
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Joint diameter in extension: 25 mm
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Joint diameter in compression: 27 mm
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Maximum tensile resistance: 320 kgf
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Maximum axial compression: 45 kgf (in casing), 22 kgf (no casing)
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Minimum axial compression to provide snug fit in casing: 10 kgf
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Maximum joint bend angles: 45° (larger angles permitted when stored on factory reel in factory orientation)
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Smallest bend radius for 27 mm ID conduit which allows for extraction: 3,5 m for SAAF500, 2,0 m for SAAF305
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Storage temperature: -40°C to 60°C
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Installation temperature: -5°C to 60°C
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Operating temperature: -35°C to 60°C polynomial temperature algorithm corrected
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Waterproof to: 980 kPa
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Power requirements: 12 VDC at 4,2 mA/segment
Dynamic Acceleration Measurements:
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Range: ±1,7 G
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3dB Bandwidth: 50 Hz
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Noise floor of MEMS: 110 µG/Hz0,5
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Data rate: SAA232: 38,4 kbps to 230,4 kbps
Static Shape Measurements:
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Angular range of MEMS sensors: 360° (software selection required for 2D/3D modes)
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Range of 3D mode (vertical): ±60° with respect to vertical (SAARecorder alert at ±70° w.r.t. vertical)
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Range of 2D mode (horizontal): ±60° with respect to horizontal
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Range of 2D mode (mixed H/V): ±180° with respect to horizontal
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Long-term accuracy relative to starting shape: ±1,5 mm for 32 m SAA
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Long-term resolution relative to starting shape: ±0,5 mm for 32 m SAA
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Long-term accuracy of tilt/segment within 20° of vertical: ±0,0005 rad = 0,029°
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Azimuth error in joints: < ±0,25°
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Orthogonality error in joints: ±0,1°
