Radiometric safety monitoring offers visible benefits
22 February 2011
In addition to their temperature measuring duties, thermal imaging cameras can also offer cost-efficient monitoring and control capabilities, and are being used increasingly in safety monitoring applications
Many infrared cameras are radiometric and are therefore able to measure and analyse temperature, a fact that is leading to increasing use of thermal imaging cameras for plant safety functions. Indeed, FLIR Systems tells CEE magazine that safety is one of the largest growth markets for static thermal imaging cameras, saying it also has models available that can output this data via email to flag-up a problem or use it to trigger an alarm or a synchronised function.
Infrared cameras are able to provide live, high-resolution images and some have a time-saving measurement masking feature that enables areas of thermal interest to be selected. They remain fully operational, day and night, even when smoke or mist clouds the field of view. Sophisticated software allows multiple cameras to be run simultaneously and standard protocols such as GigEVision and GenICAM help to substantially cut down their integration time.
Quantifying the risk
Usually, the risk areas in a production process and the assets most critical to manufacturing continuity can be easily identified. The challenge is in knowing exactly where or when a problem might occur and quantifying its severity.
For certain industries this ability is vital. In oil and gas production and power generation there is a fundamental need to automatically and continuously detect flares to prevent the outbreak of fire. Similarly, the integrity of critical vessels and infrastructure has to be monitored to avoid downtime and ensure on-site safety.
Infrared is able to meet all of these demands. A camera can be installed discretely almost anywhere to monitor a production processes, safeguard plant and assets and measure temperature differences so that the criticality of the situation can be assessed.
Bulk storage of any combustible material - such as coal, wood or waste - can lead to a fire risk. Self-ignition generally starts in the bottom layers of the stockpile. However, the continuous monitoring of surface layers will allow even subtle changes to be detected early and action taken quickly to prevent fire from breaking out.
One example of an effective solution is offered by systems’ integrator Enelex, to monitor a coal storage facility for a Czech customer. The large size of the storage yard meant the use of portable infrared was not a practical solution for this critical task. Only a fully automated system would be able to provide constant monitoring of the many thousands of tons of coal stored on this 800m x 200m site.
The specified system is based on FLIR A-Series cameras mounted on five steel masts at strategic locations around the site. They are configured to generate a direct alarm output to an operator if previously defined maximum temperature thresholds are exceeded. Acoustic and display alarms on a monitor draw the operator’s attention to the possibility of a spontaneous fire. Data transfer is via 3km of fibre-optic cables to the control room.
The same camera is also central to a new fire prevention system called PYROsmart. The system, developed by German company Orglmeister, can scan a large area and all the separate thermal images that are taken are stitched together to create a single composite image that is continuously updated.
By combining all the 640 x 480 images created by the camera, an image of up to 9600 x 9600 pixels can be achieved. The user can easily set various types of rules in the PYROsmart system and any violation will result in the automatic sounding of an alarm.
A thermal imaging camera can also offer an alternative to its visual counterpart in flare detection. Changes in temperature and pressure during the production process at oil and chemical processing plants can generate excess gas. To protect staff and equipment the pressure is relieved by diverting the excess gas to a flaring device. It is here that the infrared camera’s ability to see through smoke and be equally effective day and night offers many benefits.
Thermal imaging is proving itself to be highly valuable in safety applications both as a solution in its own right and in systems which combine visual and thermal technologies. Thanks to its application scope the technology is now widely commercialised and is affordable. When personnel safety, loss of property, water damage from fire-fighting and loss of production are factored in to the equation, infrared is a modest investment.
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