A vibration monitoring sensor measures various parameters to identify changes in machine behavior. They help save money and time, reduce catastrophic failures, and improve the functioning of machines.
Vibration Monitoring 101
Abnormal vibration in an industrial machine should be detected early and repaired before machine failure can occur. Such failures are potentially costly in terms of time, cost, and productivity. Measuring vibration allows industrial plants to increase efficiency and save money.
A broken piece of equipment or machinery may lead to high repair and maintenance costs and thus real time vibration monitoring is the most effective way to prevent such losses. The following Critical machines are always given priority over other machines.
- Machines that require expensive, lengthy, or difficult repairs if broken down
- Machines that are critical to production or general plant operations
- Machines that are known to frequently suffer damage
- Machines that affect human or environmental safety
How Vibration Monitoring Sensors Work
Every rotating machine has its own unique vibration characteristics. Problems such as unbalance cause these characteristics to change. As with most other industrial sensors and transducers, it is critical that the vibration sensor is well suited to condition monitoring applications
The most effective system is a fully integrated monitoring system to protect machinery and plant. For such installation, sensors with a DC output are more suitable.
This type of vibration sensor produces an output proportional to velocity or acceleration in the range of 4-20ma. This means they can be used with most PLCs to continuously monitor plant equipment and machinery.
Mounting Vibration Sensors
Most machines involve rotary mechanisms. Motors, pumps, compressors, fans, conveyor belts, and gear boxes all involve rotary mechanisms and are frequently used in machines.
Most rotary mechanisms have bearings that support the weight of rotating parts and bear the forces associated with rotary motion and vibration.
Large amounts of force are borne by bearings. It is thus not surprising that bearings are often the place where damages first occur.
Vibration measurements are usually taken at the bearings of machines, with the sensors mounted at or near the bearings. If the sensor is treated roughly, it may produce unreliable signals.
The accelerometer must never be mounted on a very flexible part of the machine, as the spectrum will be distorted by the flapping of the flexible part.
Bearings are typically the place where damages first occur.
Precautions to Take When Mounting Vibration Sensors
Be careful when mounting your vibration sensors to ensure proper installation.
- Mount as close as possible to the bearing
- Make sure the accelerometer is firmly attached
- Make sure the accelerometer is oriented correctly
- Mount the same accelerometer in the same location
Take Care of the Accelerometer
The parameters used for measuring vibration determine:
- How data is collected
- How much or how fast data is collected
- How data is processed
- How data is displayed
Critical to vibration monitoring is the machine mounted sensor. Three parameters representing motion detected by vibration sensors are displacement, velocity, and acceleration.
- Displacement Sensors – Displacement sensors are used to measure shaft motion and internal clearances. These sensors are best suited for measuring low frequency and low amplitude displacements typically found in sleeve bearing machine designs.
- Velocity Sensors – Velocity sensors are used for low to medium frequency measurements. They are useful for vibration monitoring on rotating machinery and have lower sensitivity to high frequency vibrations and are thus less susceptible to amplifier overloads. The piezoelectric sensor is versatile, reliable, and the most popular vibration sensor for machinery monitoring.
- Piezoelectric Sensors – The solid-state construction of industrial piezoelectric sensors enables them to operate under most harsh environmental conditions. They are unaffected by dirt, oil, and most chemical atmospheres.
Choosing an Industrial Vibration Sensor
When selecting an industrial vibration sensor, many factors should be considered so that the best sensor is chosen for the application. Such factors include the vibration level, frequency range of interest, temperature range and whether corrosive chemicals are present.
Primary vibration sensor considerations are the sensitivity range and the frequency range.
- Sensitivity Range – The sensitivity of industrial accelerometers typically range between 10 and 100 mV/g. To choose the correct sensitivity for an application, it is necessary to understand the range of vibration amplitude levels to which the sensor will be exposed during measurements.
- Frequency Range – In order to select the frequency range of a vibration sensor, it is necessary to determine the frequency requirements of the application.
There are also some environmental requirements to consider.
Sensors must be able to survive temperature extremes of the application environment. Temperature transients can cause metal case expansion resulting in erroneous output during low frequency measurements.
Vibration monitoring sensors are sealed to prevent the entry of high humidity and moisture.
High Amplitude Vibration Signals
The sensor operating environment must be evaluated to ensure that the sensor’s signal range covers the vibration amplitude of interest. Exceeding the sensor’s amplitude range can cause signal distortion.
Vibration sensors certified as being Intrinsically Safe should be used in areas subjected to hazardous concentrations of flammable gas, vapor, and mist.
Other Sensor Types
- High Temperature Piezoelectric Vibration Sensors – High temperature industrial sensors are available for applications up to 1400° F.
- Triaxial Sensors – Various industrial players use triaxial vibration sensors for multi-directional machine monitoring and balancing. These devices contain three sensors which give the user more information concerning machinery health than conventional single-axis units.
Get Vibration Sensors for Your Conveyor Belt Systems Today!
Ready to get started with vibration monitoring? Contact Machine Saver, Inc. and we can help you get all the information you need. Plus, we can help you find the perfect vibration sensors for your conveyor belts and other machines.
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How Vibration Monitoring Sensors Work | Machine Saver, Inc. – Houston, TX