Inspection: A hot topic!

Thermal imaging cameras can be used for both routine and predictive maintenance. Mike Murley, product manager for thermal imaging, gas and emissions at Testo, looks into the benefits and applications, and explains what to look out for when choosing a camera.

There are many benefits to using thermal imaging cameras. As a maintenance tool, these can not only be used to carry out diagnostic work, but they can offer a solution for preventative or condition maintenance. An advantage here is that the cost of maintenance can be greatly reduced by predicting when repairs or routine maintenance are needed; and planning when maintenance is carried out can help to minimise downtime.

In addition, being a non-contact technology, inspection can take place even on live systems where there could be dangerous temperatures, electrical currents or high speed moving parts. As a result, systems can be inspected under real operation conditions, enabling mission critical or high value processes such as manufacturing to continue while the thermal inspection is being carried out.

Thermal imaging cameras can be used to detect mechanical wear and tear – such as when a worn bearing is put under load and gets hot. Without this being detected, a catastrophic failure could occur.

The technology is also a great tool to assist with optimising energy consumption – for example, for regularly checking the seals around cool room doors. Leaks will show up clearly as cool air escapes from the door, or as warm air enters the cool room, if the image is taken from inside. Similarly, oven door seals can be checked to ensure heat is not escaping.

Furthermore, while a large proportion of downtime is caused by electrical faults, some could be avoided through regular thermal inspection of electrical wiring and distribution panels. Using a thermal imaging camera it would take just minutes to see if electrical connections are getting too hot and need to be renewed – helping to avoid the costs of unscheduled downtime or even electrical fires.

For the smooth running of machinery and processes, keeping fluids topped up is often important. Thermal imaging cameras can be used here, too, to check vessel fill levels quickly. As the liquid either warms or cools the surface of the vessel, the level can be easily seen with the thermal image without the need to carry out a physical inspection.

An important aspect of any professional thermal imaging solution is the analysis and reporting package – and keeping track of inspections by downloading the images for cataloguing, distribution and analysis is very useful.

With thermal analysis software, the technician can make measurements

on the captured thermal images and compare them with previous inspections, meaning anomalies can be seen as the condition of equipment changes over time. It is also possible to add annotation to images to instruct the maintenance team on what to repair, or brief management to assist with budgeting.

Camera features

When choosing a camera, technical specification is probably the most important factor. As a general rule it is advisable to buy the best resolution you can afford, which means looking for the camera with the most pixels. The more pixels available, the more detail can be seen from the thermal images.

Thermal sensitivity can also be an important factor. Many cameras offer 100mK which means the camera can detect differences in temperature down to 0.1°C. Higher specification cameras such as the Testo 875i series offer 50mK which means the thermal differences are even clearer, making it easier to diagnose faults or look for problems.

Thermography usually involves taking still images of the subject and analysing the temperatures. The ultimate solution for analysing dynamic temperature, however, is to use a camera with Radiometric Video. This means it captures a thermal video which includes all of the measurement data.

Another useful feature is Site Recognition, which means the camera automatically recognises the object which is being inspected using a site recognition label. When the images are downloaded to computer they are automatically archived to a dedicated folder. This feature is available on Testo’s 885 and 890 high end cameras.

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