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SLOPE INDICATOR - EL BEAM SENSORS |
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Application |
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EL beam sensors are used to monitor differential movement
and rotation in structures. Typical applications include:
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Monitoring stabilization measures, such as pressure
grouting and underpinning.
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Monitoring structures which may be affected by nearby
tunneling and excavating.
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Evaluating the performance of bridges and beams under
load.
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Monitoring the stability of structures in landslide
areas.
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Monitoring the deflection and deformation of retaining
walls.
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Monitoring convergence and other movements in tunnels.
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Specifications |
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The beam sensor consists of
an electrolytic tilt sensor attached to a rigid metal beam. The tilt sensor
is a precision bubble-level that is sensed electrically as a resistance
bridge. The bridge circuit outputs a voltage proportional to the tilt of the
sensor. The beam, which is typically one to two meters long, is mounted on
anchor bolts that are set into the structure. Movement of the structure
changes the tilt of the beam and the output of the sensor
The voltage reading from the sensor is converted to a
tilt reading in mm per meter. Displacements are then calculated by
subtracting the initial tilt reading from the current tilt reading and
multiplying by the gauge length of the sensor (the distance between
anchors). When sensors are linked end to end, displacement values can be
accumulated from anchor to anchor to provide a profile of differential
movements or settlements.
Because the beam sensor has a very narrow range, it is
necessary to "null" the sensor at installation time. This provides the
maximum measurement range and also takes advantage of the sensor's best
characteristics. The
EL Nulling Device or the
EL Data Recorder
are convenient tools for the nulling operation. |
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Advantages |
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High Resolution:
The EL beam sensor can detect a change in
tilt as small as one second of arc, equivalent to a movement of 0.005 mm
per meter of beam.
Reliable
Measurements:
Since the EL beam sensor has a defined
gauge length, changes in tilt can be converted simply and accurately to
millimeters of movement, regardless of the rigidity of the structure.
Linked end to end, beam sensors can provide absolute displacement and
settlement profiles.
Convenient to
Install:
A low profile design makes the EL beam
sensor practical to install in tunnels and other locations where clearance
is important. The length of the beam can be modified to fit the structure,
and special mounting brackets provide easy installation on curved or
distorted surfaces.
Simple and Robust:
The electrolytic tilt sensor has no
moving parts, and its insulated packaging provides thermal symmetry,
shielding it from the effects of temperature gradients and radiated heat.
Remote Readout:
In construction-control applications,
beam sensors are connected to a data acquisition system that continuously
monitors movements and triggers alarms when threatening movements are
detected. In less critical applications, beam sensors can be read manually
at a remote terminal box with a hand held readout.
Cost Effective:
The EL beam sensor provides reliable,
high-resolution measurements, is simple to install, and is easily
connected to a data acquisition system. It represents an efficient and
economical alternative to precision leveling surveys and settlement
profiling systems.
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| * Click to download
datasheet [EL Beam Sensors] |
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