Vibration measurement for predictive maintenance benefits many industriesAmy J. Born | July 28, 2020
Manufacturers understand the importance of maintenance to keep their operations running smoothly. Neglected maintenance and service issues can cause inefficiencies long before equipment completely breaks down and equipment failure can result in costly delays and repairs. However, shutting down machinery prematurely or unnecessarily to perform preventive maintenance according to a schedule can also be costly in terms of downtime and wasted effort. Predictive maintenance provides information that allows operators to perform maintenance tasks with the least disruption to operations.
Vibration monitoring is one of the most commonly used predictive maintenance methods. Subtle changes in a machine’s vibration can indicate an impending problem.
Vibration measurement devices come in several forms including sensors, transducers, transmitters and switches. Accelerometers, which are generally not considered vibration sensors, can be used for this purpose as well. Vibration monitoring can detect changes in rotating components that make very small movements, such as rolling bearings. A small degree of vibration is normal when equipment is functioning correctly. As faults develop, the bearings emit a higher frequency that can be picked up by the monitoring equipment and communicated to maintenance engineers.
How do various industries use vibration measurement? Requirements for vibration measurement devices vary depending on the conditions in which they will be used. Variations exist in vibration level and frequency range.
Food and beverage
Spoilage and cleanliness are two major concerns in the food industry. Equipment failures can result in substantial losses due to insufficient refrigeration or product contamination, for example. Vibration sensors used to prevent this must adhere to strict food industry hygiene standards. Stainless steel is a good material choice because it resists corrosion from chemicals and cleaning fluids, and holds up well through frequent washings.
Vibration sensors for metalworking machinery must be robust enough to withstand flying debris, heat, dust and corrosion. High signal-to-noise ratio is another important feature.
Environmental factors play an important role in specifying vibration monitoring in mining applications. Temperature and humidity affect performance. The proximity to corrosive chemicals and explosive gases underground must also be considered. Vibration monitoring of crushers, pumping systems, vibrating screens, load-out facilities and truck fleets provides invaluable information for site engineers and maintenance teams regarding the health and safety of equipment.
Oil and gas
Hazardous oil and gas environments require explosion-proof, precise monitoring equipment with RFI shielding to block external electromagnetic waves and prevent interference from internal electromagnetic waves in order to reduce the chance of electronic malfunction. Oil and gas equipment that benefits from vibration sensors includes blowers, centrifuges, chillers, compressors and reciprocating compressors, cooling towers, fans, gearboxes, mixers, motors, pumps, turbines and vibrating conveyors.
Friction and impacting are two common faults in the paper industry. When either occurs, stress wave activity in the form of vibration creates a short-term ripple on the frame of the metal. This can be detected with an accelerometer. Vibration monitors should be temperature- and fluid-resistant and have a high signal-to-noise ratio.
Power plants typically have multiple generators of varying sizes. Major machinery is monitored with permanently installed continuous monitoring systems, while blowout preventer (BOP) machinery can be monitored periodically because of the vast number of points that need to be monitored (700 to 800). Vibration monitors for this equipment should be heat-resistant and measure velocity and acceleration with precise sensitivity. RFI shielding is necessary for high voltage environments.
Early notification of operational problems and faults is necessary to prevent catastrophic damage to wind power applications. Vibration monitoring for predictive maintenance is used for turbines, gearbox conditions, bearing, main shaft and tower sway. The slow rotation of wind turbines necessitates vibration sensors that are small and compact with a very low frequency response (1 Hz or less).
Additional Engineering360 resources and information on vibration measurement including applications and industries, products and services, and standards can be found here.