Encardio-rite Model EAN-41M is a MEMS tilt sensor (beam sensor) designed for monitoring inclination and vertical rotation of structures. Any change in a structure that is caused due to construction activity like excavation; tunnelling or de-watering that may affect the ground supporting the structure is called a tilt change. It may also be due to the loading of the structure, such as loading of a dam during impoundment, loading of a diaphragm wall during excavation or loading of a bridge deck due to wind and traffic. The Data collected from the tiltmeter provide an early warning of possible threatening deformations, giving sufficient time to take corrective measure or evacuation of the area, if necessary.
Tilt Sensor Application
If you’re wondering where tilt sensors are used, they are used in the following monitoring activities:
Monitoring the vertical rotation of retaining walls.
Monitoring inclination and rotation of dams, piers, piles and other structures.
Monitoring stability of structures in landslide areas.
Monitoring tunnels for convergence and other movements.
Monitoring safety of structures around zones of excavation or tunnelling.
Monitoring deflection in bridges and struts under different loading conditions
Operating Principle – How does a tilt sensor work?
Tilt sensor working principle is built around the Micro-electromechanical system (MEMS). Encardio-rite Model EAN-41M beam sensor has a range of ±15°, along with high sensitivity and tilt sensor accuracy mounted inside an aluminium enclosure (beam). It provides a bipolar DC voltage output proportional to the sine of tilt angle measured by the tiltmeter. The output is zero volts for a truly vertical position.
The MEMS tilt sensor gives a comparatively low-cost tilt measurement solution and yet offers excellent resolution and long term stability. With the help of mounting accessories like brackets and anchors, the tiltmeter can be secured on any vertical surface, horizontal floor, or the ceiling.
Model EAN-41M Tilt Sensor is not designed to measure the absolute determination of tilt of structures. It measures the change in the tilt of a structure to which it is fixed. Once the instrument is mounted on the structure, the initial tilt reading is noted. Subtracting initial tilt reading from subsequent tilt reading gives the change in the tilt of structure over a period of time.
How to install tilt sensors?
Encardio-rite Model EAN-41M can be installed in horizontal as well as the vertical surface. Let’s start with the installation on horizontal structures.
Tools and accessories required for installation
Sensor mounting kits, one more than the number of beams to be mounted in series.
Two open-ended spanners of 17 mm size and one open-ended spanner of 13 mm size, or two adjustable wrenches.
One flat head screwdriver with 4 mm blade width.
Quick set epoxy grout for grouting the anchors in concrete.
Loctite 290 threads sealant or any other equivalent post assembly thread sealant.
Percussion or hammer drill with 12 mm drill bit.
Chalk line and coloured chalk.
Tape measure, longer than the maximum beam gauge length to be used.
Spirit level.
Installation of Horizontal Tilt Sensor
Installing the anchors
Horizontal sensors are designed to discover the relative vertical displacement of the two anchors at its ends. The distance between the two anchors is known as the gauge length of the tilt sensor. They are usually available in standard gauge length of 1, 2 or 3 m, but varied specified lengths are also available.
The sensors are generally used in a string with two tilt sensors sharing a common anchor for fixing.
Identify and mark the point where you want the sensors places with the help of a chalk-line and suitable coloured chalk. In the case of wall mounting, make use of a spirit level and a beam to ensure that the line is as horizontal as possible. As for floor mounting, the line should be in sync with the direction of the vertical settlement profile.
Mark off distances corresponding to the gauge length of the beams to be fixed, using a tape measure. Keep in mind that the beams are somewhat longer than their gauge length. If wanted, beams of different gauge lengths may be used in the same string. Each mark corresponds to an anchor position.
With the help of a drilling machine, dig 12 mm diameter anchor holes to a depth of about 100 mm at the marked positions making sure that the holes are perpendicular to the wall or floor surface.
Blow air or brush the debris, making the hole clear.
With the help of epoxy grout in these holes, places the longer (148 mm) anchors (figure 2) of the mounting kits in such a way that the 50 mm length of anchors projects out of the surface after fixing.
Let the grout settle for the required amount of time before handling it.
Measure & record the exact centre to centre distances between each anchor in the ...[Continue Reading]
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