Sensors in condition monitoring and diagnostic systems for fluid power.
Monitoring systems comprised of dual monitoring products are contributing to the security of pneumatic systems. They are able to prevent the adverse movement of fluid through double redundant dual monitoring products that use valves to block fluid flow and direct the fluid back to the reservoir.
These valves have built-in spool monitoring switches and facilitate the monitoring of pressure. The position and pressure information obtained from the valves can be fed into monitoring controllers to generate alerts in case of failure of the system or shut down the machine.
Flow sensors have improved the monitoring of pneumatic systems considerably, while their innovative designs have removed installation restrictions for end-users. Some of the sensors that have been developed recently do not have mounting restrictions as they work on the anemometry measuring principle. An in-built bypass system generates laminar flow inside the flow sensor, thereby eliminating the need for accessories to condition flow.
Flow sensors can also record and measure air consumption and this information is very useful in monitoring air circuits in which the air flow varies. These sensors are also highly instrumental in tracking air-leakage in pneumatic systems as they have been able to minimise the air wastage that creates energy losses. Reducing air leakage can lead to significant savings, as around 80% of costs incurred for pneumatic systems are for electricity.
Frost & Sullivan notes that the current focus in the condition monitoring area for pneumatics is to obtain more field data from pneumatic instruments. This is being pursued through the hardware, software, and maintenance service areas.
Built-in system diagnostics has progressed due to the functions offered by smart sensors. The implementation of microprocessor control and programmability in conjunction with the sensors has enabled advanced diagnostics and the ability for information output to be available in the form of a display. Several other smart devices such as valve terminals enable point-level diagnostics that can identify specific sensor channels that are the sources of errors. Module and channel-specific diagnostic information can be obtained and identified from among signals produced by sensors, such as flow sensors, pressure sensors, and level sensors. These smart devices can be used to detect abnormalities such as short-circuits in sensors, low voltage and undesirable valve functions.
Diagnostics technology is advancing mainly in terms of developing robust systems that include all components in a pneumatic system, right from the air supply end to the actuator end. Valves, drives, sensors, and other units are integrated into one system to enable comprehensive diagnostics and control.
Software tools are also being developed to analyse incoming data and compare them with optimum parameters. Based on the output from the comparison, the software suggests improvements to the performance of the pneumatic system.
The highest standard in diagnostics and prognostics appears to be the WatchDog agent, which is being tested and adopted by a large number of manufacturing companies. WatchDog is an intelligent, prognostic maintenance platform developed by the Center for Intelligent Maintenance Systems at the University of Cincinnati, Ohio. It embodies a paradigm shift in product performance degradation assessment and intelligent maintenance systems.
The WatchDog Agent is designed to be able to assess and predict the performance of a particular process or piece of equipment in accordance with data input from sensors, historical data, and operating conditions. The intelligent maintenance system would thereby facilitate scheduling maintenance at the optimal time.
For more information on Frost & Sullivan’s technical and market analysis, please contact Patrick Cairns on [email protected].
For more information contact Patrick Cairns, Frost & Sullivan, +27 (0)21 680 3274, [email protected], www.frost.com
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