Thermal imaging cameras are an increasingly popular tool used to assist maintenance operations throughout many industries. These practical tools enable technicians and engineers to conduct productive surveys efficiently and with minimal impact on the business's daily operations.
As a result, the usefulness of thermal cameras has extended to commercial sectors, and they have even been used for domestic home surveys. But despite how easy these cameras are to use, the way they work is very complex and still a mystery to many operators.
What Is Infrared?
Infrared radiation (IR), otherwise known as near-infrared or far-infrared, is a form of electromagnetic radiation that is invisible to the human eye. The human eye can only see a limited section of the electromagnetic spectrum.
IR has a wavelength of around 1 millimetre or 300 Gigahertz (GHz) toward the red edge of the visible light spectrum. Longer IR wavelengths of 30 microns (μm) are sometimes included in the terahertz radiation range. Infrared waves travel at the speed of light (299,792,458 meters per second). William Herschel discovered infrared light in the 1800’s. He conducted an experiment where he used a prism to split visible light into a rainbow pattern and measured the temperature of each of the visible colours with individual thermometers placed within those segments of the rainbow. During this experiment, he noticed that the light was warmer toward the red segment and beyond into areas where there was no light visible. Within the electromagnetic spectrum, infrared radiation waves are present above those of microwaves and just below those of red visible light which is why it’s been named infrared.
Characteristics Of Infrared Radiation
The radiation that makes up infrared is also referred to as heat, thermal or electromagnetic waves. This is due to its heat-inducing nature. Infrared waves are used in many applications where heat production is needed, such as infrared heater therapeutic applications during medically required physical therapy.
Near-infrared rays are used in many electronic applications such as TV remote controls and cameras. The wavelength ranges of near-infrared are closer and have applications similar to visible light applications.
Far-infrared rays are more thermal in nature. Max Planck’s law of radiation states that the warmer an object is, the greater its emission is at each wavelength and the shorter the wavelength at which they peak. For example, the peak of these emissions would be far sooner for the heat of a 300°C soldering iron (5 micrometres) over the average 37°C of a person (9.3 micrometres). Visible light is 0.5 micrometres, a much shorter wavelength than infrared.
All objects above absolute zero temperature will emit infrared radiation. This is commonly felt as heat through the nerves in our skin but can also be viewed through a thermal imaging camera. The intensity of the radiation is detected by the camera sensor and displayed.
How Do Thermal Cameras help?
The feature that defines thermal cameras is their ability to read these infrared waves, and a conventional camera would read regular light waves. For your standard camera, visible light hits an object and is reflected, and then the detector in the camera captures the reflected light and turns it into an image. Thermal imaging is the process of capturing the infrared energy emitted from the object and using the data to create the thermal image for analysis.
Standard glass lenses do not conduct infrared energy well, which is why our cameras use silicone or germanium lenses, a far superior transmitter of this radiation. The radiation is captured through a detector and then interpreted by the internal electronics. The camera's internal chip will process these signals into a mathematical calculation and create the colour map you see on the back of your camera. This is the process of converting the infrared image into a radiometric one. A radiometric image allows temperatures to be read from the image.
This efficient visual interpretation of thermal energy is the key to the popularity of thermal cameras. The colour map lets users quickly identify and locate locations with unusual temperature variations. These will be revealed either as bright yellows and oranges for overheating components or dark blue or black for very cold areas. But when choosing one of our used thermal imaging cameras, you can also decide on your own palette to best suit your environment.
This feature alone can only tell so much, though thermal surveys provide the best results when conducted regularly, and the results are recorded for comparison. By comparing new surveys with an older baseline survey, the difference will stand out more and assist you when planning any future maintenance.
What Is Thermography?
Thermography can be split into two types, active and passive. Active thermography requires the object's surface to be heated; this generated heat is then monitored as it cools. Active thermography is a less versatile form of thermography that will reveal any potential flaws within a material as the heat decay will be uneven. These tests are often used for aerospace, defence and other industries that demand stringent quality control tests.
Passive thermography is far more commonplace. These tests are non-invasive as they only assess the natural temperature of the object. These passive surveys can reveal a lot about a machine or building by showing the temperature of its components. Unusual temperature changes can signal any number of problems, as no matter the context, a significant change will reveal that something is not operating as it usually should.
Where Are Thermal Cameras Used?
Thermal imaging cameras were initially developed for military applications. The first camera for the military was created in 1958 by AGA Bofors in Sweden. But they have grown into a far more versatile tool. Thermascan has provided thermal imaging cameras for hire and sale to various industries and commercial sectors.
Thermographic building surveys are one of the most popular uses for a thermal camera. This powerful, non-invasive tool is perfect for monitoring and assessing the condition of a building. These cameras are also an excellent assistant when diagnosing any problems with a facility, such as the electrical system, plumbing or insulation. For example, there may be a damaged wiring section within the building. By conducting a thermal survey of the electrical systems, the user will see where the heat from the electrics is absent and conclude this as the location where the electrics are damaged. This non-destructive survey allows the building owner to limit the damage of any needed repairs.
They have also been used for industrial applications such as preventative machine maintenance. For example, accumulated heat within machine components is a reliable sign of something wrong. For instance, if a rotating part starts to grind against another, it will generate friction-based heat. If this is not fixed, the pieces will continue to wear down until they cannot function. A thermographic survey with a thermal imaging camera will reveal this heat on its colour map and allow the site manager to decide the best course of action.
At Thermascan, we pride ourselves in supplying a broad range of FLIR thermal cameras for sale and rent to assist businesses nationwide with their maintenance needs. You can learn more about the range of cameras and thermographic services we provide here.