Understanding the Benefits and Limitations of Infrared Thermography in Plant and Machinery Maintenance

Due to the non-destructive nature of this technique, readings are taken away from the surface being monitored. This means the surrounding environment can affect your measurements.

Here are some environmental factors you should know: 

• Temperature - Whether it be ambient temperature or heat emanating from neighbouring machines, environmental temperature can distort your readings
• Humidity - If humidity is too high it can cause the surface of the object being measured to retain more heat than normal. As the measuring technique is based on relative temperature differences, irregular heat retention could affect the reading accuracy
• Wind - Something as simple as a draft can make the heat on the surface being measured dissipate faster than normal. Again this manipulates relative temperature differences, leading to unreliable results
• Sunlight - As sunlight can change quite dramatically throughout the day, any light hitting the surface being measured will cause erroneous temperature fluctuations. Artificial light can also affect readings. However, as room lighting intensity is generally constant, it is possible with current technology to calibrate your device to minimise its impact

Reflective surfaces such as metal, glass, or liquid can reflect radiation from other sources, like sunlight. Infrared radiation can be reflected in irregular directions, distorting the thermal image. Reflections can also create hot spots or false readings. Taking readings on a surface with little or no reflection is always advisable. Sometimes reflective surfaces cannot be avoided and in some cases, special coatings are used to reduce reflective properties.

For infrared thermography, surface emissivity is a fundamentally critical material property of the object being measured. Emissivity shows us how well a surface emits or absorbs infrared radiation. If it is low, the amount of infrared radiation it emits is low. This means we cannot discern the true temperature of the surface, making it more likely that any readings you collect are from the surrounding environment. Consequently, a high emissivity means our measuring device can sense an increased quantity of infrared radiation coming from the material being monitored. This gives you more accurate readings.

There are also limitations to the equipment itself. Some of these will vary depending on the infrared thermography device specifications you choose:

• Temperature range - This is governed by the detector sensitivity in your device. Both the temperature range and accuracy within that range should be considered when making your decision
• Proximity - The distance from the detector to the object being measured can affect your reading accuracy
• Line-of-sight - There needs to be a clear line of sight from object to detector. Anything obstructing the path to the detector will again affect or completely block your readings
• Resolution - The resolution of radiation detection will vary depending on your device's specifications. This will affect the level of detail in your readings

Without the right level of training and experience, it is possible for users to misinterpret readings or fail to consider the limitations and potential interference of infrared thermography. This will lead to inaccurate data collection and the potential for irreparable damage to the machinery or process being monitored.

Predictive maintenance is one of the key advantages of infrared thermography. Being able to detect tell-tale signs of potential problems that would not normally be visible to the naked eye allows you and your team to make the necessary adjustments or repairs to your equipment to keep things operating smoothly and prevent costly damage to your equipment.

Taking measurements with laser-like precision allows you to assess every aspect of your equipment or processes. Along with accurate measurements that can detect the smallest fluctuations in temperature changes, these details make all the difference.

The ease and speed at which you can take readings - with some devices able to take simultaneous readings of multiple machines - greatly reduces the time and effort required to maintain your equipment. That, along with the ability to identify and address issues before they become serious problems, makes these devices a clear cost-benefit for your business.

Demand for non-invasive monitoring of plant and machine maintenance continues to drive development in thermal imaging. As technology advances and researchers find effective ways to mitigate limitations, we will see higher resolutions and increased accuracy in these devices.

It is also highly probable that with the current exponential improvements in artificial intelligence and machine learning technologies, we could soon see on-board or remote analysis of thermal readings or images with relevant, applicable guidance and recommendations for machine maintenance and repair - perhaps even in a fully automated way. Further speeding up diagnosis, error correction, and damage prevention, resulting in increased productivity, cost-benefit, and greater return on investment.

While we eagerly wait for these advancements, why not look at the devices currently available and see how they can improve your plant and machinery maintenance processes?