Extensometer Model EDS-70V/EDS-70P (MTI.EWS,ER.M-EDS-70V/EDS-70P). The borehole extensometer measures extension (displacement) that takes place with time in a bored hole or in several bored holes in a rock mass. The borehole extensometer essentially consists of one or more anchors and a reference. The anchor or anchors are set in the same borehole or in different boreholes drilled adjacent to the first borehole. They help to accurately measure distance between the various anchors with respect to the reference and monitor their relative
displacement with passage of time.
It is usually assumed that the deepest anchor is in stable
ground and so any change in the anchor spacing is
interpreted as sag of the roof bed, movement of side wall
or slope, settlement of the foundation etc.
Extensometer Model EDS-70V/EDS-70P
• Range (mm) 50, 100, 150
• Accuracy ± 0.2 % fs normal, ± 0.1 % fs normal
• Sensitivity ± 0.02 % fs
• Non linearity ± 0.5 % fs
• Temperature limit - 10 to 800C (operational)
• Thermistor YSI 44005 or equivalent (3 kOhms at 25°C)