Introduction
What is infrared thermography?
Infrared thermography is the most common way of utilizing a thermal imager to distinguish radiation (heat) coming from an object, converting it over to temperature and showing a picture of the temperature dispersion. Photos of the detected temperature distribution are called thermograms, and they make it possible to see heat-producing objects invisible to the naked eye. As a result, it’s widely utilized in predictive maintenance and thermography condition monitoring.
Since all items above outright zero (- 459.67 degrees Fahrenheit) emit thermal infrared energy, thermal imagers can detect and display infrared wavelengths without much of a stretch, paying little heed to ambient light. As a result, infrared thermography is normally utilized in an assortment of businesses and applications, including:
Machine thermography condition monitoring
Building diagnostics such as roof, moisture and energy-loss inspections
Medical imaging like peripheral vascular disease, thyroid abnormalities, metabolic and inflammatory thermography condition monitoring
Chemical imaging
Law enforcement and security imaging
Earth science monitoring
Fluid system monitoring
Electrical system monitoring
Infrared thermography condition monitoring and plant maintenance are used in applications like:
Observing the electrical and mechanical conditions of a motor
Bearing inspections- abnormal bearing friction
Monitoring refractory insulation
Locating gas, sludge levels and liquids
Types of Infrared Thermometers
In its most fundamental structure, an infrared thermometer comprises a lens that focuses the infrared thermal radiation onto a detector, which transforms the radiant energy into a colour-coded signal. Infrared thermometers are intended to measure temperature from a distance, preventing the requirement for contact with the object from being estimated. At present, there are different varieties of infrared thermometer configurations for particular applications. Following is a glimpse at three of the most widely common sorts of infrared thermometers.
Spot infrared thermometers: A pyrometer is also called a pyrometer. A spot infrared thermometer looks like a handheld radar gun and is utilized to detect and map the temperature at a particular spot on a surface. Spot infrared thermometers are great for measuring thermal radiation on hard-to-reach assets or operating under extreme conditions.
Common applications for using spot infrared thermometers for preventive maintenance consists of:
Monitoring electrical rooms
Checking bearings and belts
Energy audits looking for heat loss
Water leaks
fluid-handling systems
Panelboards
Rotating motor monitoring
Boiler operations and steam system monitoring
Infrared scanner systems: These infrared thermometers examine larger regions and are usually used in manufacturing plants with web processes or conveyors. Scanning objects on a sheet of glass, conveyor belt or metal leaving an oven are common applications for infrared scanner systems.
A thermal imaging camera is an advanced radiation thermometer that measures the temperature at multiple points across a large area and creates two-dimensional thermographic images. Thermal imaging cameras are significantly more software and hardware-based than a spot thermometer.
Infrared thermal imaging cameras help users toggle between various colour palettes and help decipher different temperatures variations. Some are- Iron palette, a black and white palette and a rainbow palette.
Also, two of the most important features one should consider are detector resolution and thermal sensitivity.
Obtaining the best image for analyzing
Just like utilizing a digital single-lens reflex (DSLR) camera, you will need to adjust to get the best thermal picture out of your camera. Consider adjusting the focus, emissivity setting, reflective temperature setting and thermal tuning. Emissivity refers to the measure of radiation an object is given contrasted with if the two items were a similar temperature.
How to use Infrared Thermography?
Infrared thermography is an important device for condition monitoring and preventive maintenance. In addition to the fact that it allows you to identify thermal abnormalities of machines, it allows you to do so in a non-intrusive, hands-off way while getting results in real-time. Thermographers ordinarily utilize one of three methods when performing thermal inspections:
Comparative thermography,
Baseline thermography and
Thermal-trending thermography
Infrared Thermography Assessment Criteria
When utilizing infrared thermography condition monitoring, it’s suggested you set up severity criteria. Severity criteria can be introduced in two structures: general categories identifying temperature levels or specific categories of machines or parts.
Relative temperature criteria: There are many safety rules dependent on temperature rises isolated into classes. For instance, you might have intermediate, advisory, serious and critical categories.
Absolute temperature criteria: A thermographer may utilize material or plan criteria dependent on the extreme reasonable temperature obtained from recently distributed data.
Profile assessment criteria: When you compare temperature contrasts and patterns across any surface, you are rehearsing a cycle known as profile assessment.
Interpreting Infrared Data Correctly
As mentioned earlier, ease of use is why infrared thermography condition monitoring has become a generally utilized tool for preventive maintenance. In any case, deciphering the information and comprehension imager abilities can prompt some normal missteps. These include:
Not understanding resolution: Infrared thermography imagers have constraints on what they see and measure.
Discounting ambient conditions: Wind, rain, ambient air temperature, and sunlight factor into the last temperature estimation.
Disregarding cold spots: While it is a given that you will be searching for spots, in some cases, the issue comes from cold spots.
Solely focusing on surface temperature: Thermal imaging isn’t extraordinary at showing precise temperatures due to ambient factors. Along these lines, focus on differences in thermal patterns as opposed to the apparent temperature.
Infrared Thermography Testing Techniques
With regards to infrared thermography testing strategies, there are a few options from which you can pick. Your choice will rely upon the considerations examined above, including what set of data you’re requiring and what you’re checking. The most well-known infrared thermography testing methods:
Passive thermography: This infrared thermography testing method takes thermal images while the machine is running or immediately after operation.
Active thermography: This method requires an external energy source to make temperature fluctuations in the component affected by inside materials and deformities.
Flash thermography: This method utilizes light beats to find gaps, inclusions or different obstacles that block heat flow into a component.
Vibrothermography: By bringing acoustic waves into a component or machine, vibrothermography can figure out where cracks might have been framed in the material.
Lock-in thermography: Like a large number of different methods, lock-in thermography necessitates that an external energy source (light, sound, heat, and so on) be applied to a component’s surface to uncover abnormalities beneath the surface.
Infrared Thermography and Preventive Maintenance
Infrared thermography is a strongly suggested preventive maintenance tool in almost all industries. You will not discover another apparatus that gives you such accurate, real-time data without upsetting the process flow from closing down your systems. Working infrared thermography into your consistently scheduled maintenance strategies is an extraordinary way of rapidly getting irregularities in parts and machines. In addition, utilizing baseline thermography on new equipment or after fixing gear will give a bunch of thermal pictures to look at any other tests against and lets you all more effectively investigate future issues. (thermography condition monitoring)
Advantages and Disadvantages of Infrared Thermography
Advantages:
Requires no contact with parts or machines
Constant output
Can acquire data on enormous surface regions all at once
Simple to-peruse visual pictures
Data can be transferred to software for additional analysis
Infrared cameras offer extraordinary mobility
No downtime or production interferences for testing
Disadvantages:
Infrared equipment is genuinely costly. You should consider the expense of the time and labour required, just as the savings you will get with early detection warnings from infrared technology.
Infrared technology cannot identify temperature if a part is isolated by a non-transparent material, for example, a glass cover. This is because when seen with an infrared imager, glass shows up in a non-transparent way.
Infrared data requires critical skills and a broad knowledge base to assess imaging results.