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In this video we will simply explain what kind of vibration measurements you should take. What vibration limits are and what an acceleration sensor and a vibration meter or analyzer is.
Here you can DOWNLOAD ADASH VIBRATION LIMIT CHARTS: https://adash.com/support/datasheets...
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The most commonly used acceleration sensor in industry is a piezoelectric acceleration sensor.
A piezoelectric crystal generates an electric charge when it is deformed – meaning compressed or stretched. To ensure deformation of the piezoelectric crystal you can see that there is some preloaded mass on it. The electric charge is transferred into the electronics of the sensor where the electric charge is converted to Voltage. This voltage is then transferred into your vibration meter through the sensor connector and cable.
In other words, the sensor is shaking on the running machine. The preloaded mass is deforming the piezoelectric crystal and this generates a Voltage signal on the output of the sensor.
A vibration meter or analyzer is an electronic device which is able to process vibration signals. If we think about it again in a very simple way, imagine that your vibration meter or analyzer is a volt meter.
The sensor is generating a Voltage signal while it is shaking on the machine. This voltage signal is transferred through the cable to your vibration device. But your vibration device will not show you volts. It is smarter that volt meter. The Vibration device is able to process the voltage signal and display vibration values such as acceleration and velocity.
There are some limit vibration values which can be considered as values indicating a worsening machine condition. We can set up the limits according to some experience with certain machines. There are also for example ADASH and ISO 10816 standards for those limit values. Or the ADASH DDS software can set up the limits automatically based on statistics from the previous measurements.
All mechanical faults which are related to the speed of the machine such as unbalance, misalignment and mechanical looseness are considered to be low frequency vibrations.
These vibrations are measured as velocity in mm/s or inches/s. (Maybe you are asking now how you can measure velocity with an acceleration sensor? With an acceleration sensor you measure an acceleration value, but the meter (analyzer) can convert the value to the velocity value). The most common frequency range of this measurement is 10 – 1000 Hz. This frequency range is also applied on ISO 10816 standards. These standards take into account the size of the machine and its foundation.
Adash has defined vibration limit values which are related to the speed of the machine (not to the size of the machine). The frequency of 101000 Hz is also applied.
Do not assume that a newly installed machine runs under its optimal condition! What if it was badly installed? It could be misaligned or unbalanced right from the beginning!
This way we came to the conclusion that to monitor mechanical vibrations (related to the shaft speed) of the machine we will use the measurement of Overall Velocity in mm/s (or ips) in the range of 101000 Hz. This measurement is represented by one number. Using the Adash DDS software we can trend this value in time and see its development.
A specific part of the machine which we want to monitor is a bearing. Bearings, as well as gears, generate vibrations on higher frequencies due to their construction their natural frequency.
These vibrations are measured as acceleration in a “g” value. The frequency range of this measurement may vary a lot and you should find out what would be the best for your particular bearing.
But let’s keep it simple and define your measurement of acceleration in the range of 500 – 16 000 Hz.
Adash has defined bearing vibration limits related to the speed of the machine again. The mentioned frequency range of 500 – 16 000 Hz has been applied.
So, the second measurement which we will include in our regular machinery measurement will be Overall Acceleration in g in the range of 500 – 16000 Hz. It is represented by one number. Again, using DDS software we can trend this value in time and see its development.

00:00 01:50 Acceleration Sensor principle
01:50 02:40 Vibration Meter and Analyzer principle
02:40 09:31 Vibration limits and Measurements types