These teams base their level measurement in a mechanical phenomenon called Piezo, this means we have a glass when subjected to a voltage, it starts to vibrate emitting pulses, these are emitted from the sensor level, and this, in turn, becomes a receiver, and the time it takes to travel that distance is equivalent to the level, or the measure of the distance between the sensor and the measurement surface.
In ultrasonic measurements, we must be clear whether we will measure level, that means that from a ground level up, or space, which is from the surface of the sensor to the surface of the material to be measured.
HEADS of ultrasonic sensors
Figure N ° 1 is the piezoelecrico material that emits pulses and the receiver detects the return.
Each team brings tables that define the characteristics of the measurement surface, the means of propagation of the mechanical wave (sound wave), characteristics of the pond where it is inserted, shape, material, etc.. Some times the height of the process with respect to the sea. They also have in-house temperature sensors, this allows calculations to correct changes in the speed of sound (This will be a constant that will remain for a long time = 343.2 m / s at 20 ° C).
These instruments, regardless of their strength, have some drawbacks, are affected by obstacles in the measurement mapping in your area, so it must have some consideration for assembly.
Figure N ° 2 shows us that we must do and must not, for good measure.
The installation of this equipment, in 99% of cases, should be perpendicular to the surface to be measured, if this were not possible, you should be careful that the surface which is to be measured is that of largest possible area. Remember that each team has an angle of attack and surface features closer to the sensor face will be measured, and if not we need to take us to deliver measurement errors are called false echoes.
Now that we have the basic knowledge for proper installation to define what we see now is to work with a level sensor installed, which presents operational problems.
Each team has a basic and advanced configuration, which we assume is already installed, which is operational. We should also know that each manufacturer provides a manual that presents the problems and solutions more often may occur.
We will create a list of common pitfalls and deliver the response that best chance for a good result.
Failure-level indication, this means indicating the display is not the real
Simplicity may be the solution to every problem, you see the TEAM?, This loose?, Wires exposed?, The computer is clean?, This firm?, Measuring the surface is free of interference between?
Ans: Check that the sensor membrane is free of impurities and adhering material, although some teams are able to compensate for this weakness is always important to help make this clear.
Ans: Check with the fingertips that the pulses are present in the sensor membrane, they must emit pulses at regular intervals.
Ans: Check that there is no cable without loss of protection or insulation, remember that we need, in some cases, a high voltage (approx. 500 volts) to create pulses in the piezoelectric.
Ans: Check that the sensor diaphragm is not with tears or breaks, this distorts the pulses.
Ans: Check that the measurement space is not an obstacle interference, some teams allow us in their configuration to remove obstacles to avoid disturbing the measurement
Ans: Check that supply voltage is defined by the manufacturer, Phase-Neutral-Earth
Figure N ° 3 SENSOR WITH adhered materials.
These are clear examples for a given problem we can see several solutions. We can begin to see some other solutions for different types of brands to be specific.
If there is a point that does not take into consideration or timely topic, please do get to:
Mail: hcarrasco@instrumentacionycontrol.net and we will see
Twitter: @ instrumentation
