The vibration meter is widely used by manufacturers as a tool for mechanical condition check, product testing and quality assurance purpose. Most of mechanical maintenance engineers use vibration meter device with sound level meter to analyze frequency of target equipment or devices. In civil engineering, #vibration meters is used to measure the vibrations of structures such as buildings, roads and bridges. In addition, the technicians in healthcare industry are using specialized vibration devices to measure vibration generating in the human body. The oscillograph measures one or more vibration #acceleration, vibration speed (speed), and/or vibration displacement.
Typically a vibrator is a portable device you can carry all the time. And technically it usually has memory inside for writing measurements. Most of #oscillograph models have built-in data loggers which is able to collect and record the vibration measurement data continuously. This allows the collection of vibration measurement data with great accuracy.
How vibration meter works
Vibration meter or analyzer is an electronic device which is able to process vibration signals. If we will take it again in very simple way, imagine that your vibration meter / analyzer is a volt meter. The sensor is generating 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. Vibration device is able to process the voltage signal and display vibration values such as acceleration and velocity.
How to choose measurement
What is the most common problem when using vibration measuring devices? The first issue will be what to measure first, and the second issue is what these figures tell me?
There are some limit vibration values which can be considered as values indicating a bad machine condition. We can set up the limits according to some experience with certain machines and there are also for example ISO 10816-3 standards for those limit values.
▶ Low Frequency Vibrations: All mechanical faults which are related to the speed of the machine such as unbalance, misalignment and mechanical looseness are considered as low frequency vibrations. These vibrations are measured as velocity in mm/s or inches/s. The most common frequency range of this measurement is 10 – 1000 Hz. This frequency range is also applied on ISO 10816-3 standards.
▶ Overall velocity measurement: 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 10-1000 Hz. We call this measurement a Static value as it is represented by one number.
▶ High Frequency Vibrations: A specific part of the machine which we want to monitor is a bearing. Bearings generate vibrations on higher frequencies due to their construction.
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 – 16000 Hz.
We can conclude that there are 2 key values which we should measure regularly on our machines:
● Overall Velocity in mm/s (inch/s) – lower frequency range – which indicates the general machine condition
● Overall Acceleration in g – higher frequency range – which indicates the bearing condition
(Reference source: www.adash.com)
Mobilio is a specialized company in vibration sensing solution and services.