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Thermal Imager

 


A thermal imager gun, also known as an infrared (IR) thermal imaging camera or infrared thermometer, is a device used to detect and visualize heat energy emitted by objects. These devices are widely used in various fields, including electrical inspections, HVAC maintenance, medical diagnostics, building inspections, and industrial applications. Below is a comprehensive overview of thermal imager guns, their working principles, components, applications, and usage.



What is a Thermal Imager Gun?

A thermal imager gun is a handheld device that captures infrared radiation (heat energy) from objects and converts it into a visible image, called a thermogram. This allows users to see temperature variations across the surface of an object, which can be useful for identifying hot spots, cold spots, and thermal anomalies.

An infrared (IR) thermometer is a sensor that determines the temperature of an object by detecting and quantifying the infrared radiation emitted by measured target. An IR thermometer can be compared to the human eye. The lens of the eye represents the optics through which the radiation (flow of photons) from the object reaches the photosensitive layer (retina) via the atmosphere. This is converted into a signal that is sent to the brain. Fig. 3 shows how an infrared measuring system works. 


Every form of matter with a temperature above absolute zero (-273.15°C / -459.8°F) emits infrared radiation according to its temperature. This is called characteristic radiation. The cause of this is the internal mechanical movement of molecules. The intensity of this movement depends on the temperature of the object. Since the molecule movement represents charge displacement, electromagnetic radiation (photon particles) is emitted. These photons move at the speed of light and behave according to the known optical principles. They can be deflected, focused with a lens, or reflected by reflective surfaces. The spectrum of this radiation ranges from 0.7 to 1000 µm wavelength. For this reason, this radiation usually cannot be seen with the naked eye


The invisible part of the spectrum, however, contains up to 100,000 times more energy. Infrared measuring technology builds on this. It can be seen in Fig. 5 that the radiation maximum move toward evershorter wavelengths as the target temperature rises, and that the curves of a body do not overlap at different temperatures. The radiant energy in the entire wavelength range (area beneath each curve) increases to the power of 4 of the temperature. These relationships were recognized by Stefan and Boltzmann in 1879 and illustrate that an unambiguous temperature can be measured from the radiation signal. 


Emissivity is the measure of an object's ability to emit infrared energy. Emitted energy indicates the temperature of the object. Emissivity can have a value from 0 (shiny mirror) to 1.0 (blackbody). Most organic, painted, or oxidized surfaces have emissivity values close to 0.95. Majority of Fluke Process Instruments sensors have adjustable emissivity feature to ensure accuracy when measuring other materials such as shiny metals. 

If you are using a sensor with a fixed, preset emissivity of 0.95, and need to measure a shiny object you can compensate by covering the surface to be measured with spray oil, flat black paint or masking tape. Measure the temperature of the taped or painted surface. That is the true temperature.



To optimize surface temperature measurement accuracy:
1. Determine the object emissivity for the spectral range of the instrument to be used for the measurement.
2. Avoid reflections by shielding object from surrounding high temperature sources.
3. For higher temperature objects, use shorter wavelength instruments, whenever possible.
4. For semi-transparent materials, such as plastic film and glass, assure that the background is uniform and lower in temperature than the object.


Components of a Thermal Imager Gun

  1. Infrared Lens

    • Captures infrared radiation from the target area.

  2. Detector (Sensor)

    • Converts the infrared radiation into an electrical signal. Common types include microbolometers.

  3. Processing Electronics

    • Processes the electrical signals from the detector and converts them into temperature data.

  4. Display Screen

    • Shows the thermal image (thermogram) in real-time. Can be LCD or LED.

  5. Control Buttons

    • Allow users to adjust settings such as emissivity, color palettes, and temperature ranges.

  6. Battery

    • Provides power for the device. Typically rechargeable.

Working Principle

The thermal imager gun works based on the principle of infrared thermography. Here’s a step-by-step outline of how it functions:

  1. Detection of Infrared Radiation

    • All objects emit infrared radiation as a function of their temperature. The infrared lens captures this radiation.

  2. Conversion to Electrical Signals

    • The detector inside the thermal imager converts the captured infrared radiation into electrical signals.

  3. Signal Processing

    • The processing electronics convert these electrical signals into temperature data and generate a thermal image.

  4. Display

    • The thermal image is displayed on the screen, showing different temperatures as different colors or shades.

Applications of Thermal Imager Guns

  1. Electrical Inspections

    • Identify hot spots in electrical panels, circuits, and equipment, which can indicate potential faults or overloads.

  2. HVAC Maintenance

    • Detect heat loss, insulation issues, and HVAC system performance problems.

  3. Building Inspections

    • Find moisture intrusion, roof leaks, and insulation deficiencies.

  4. Industrial Applications

    • Monitor equipment and machinery for overheating, predictive maintenance, and quality control.

  5. Medical Diagnostics

    • Non-invasive detection of abnormal temperature patterns in the human body, which can indicate various medical conditions.

  6. Firefighting

    • Locate hot spots, fire sources, and survivors in low-visibility conditions.

How to Use a Thermal Imager Gun

  1. Power On the Device

    • Turn on the thermal imager by pressing the power button.

  2. Adjust Settings

    • Set the appropriate emissivity for the material being inspected. Adjust other settings like temperature range and color palette as needed.

  3. Aim at the Target

    • Point the infrared lens at the target area. Ensure the device is at a suitable distance for accurate measurement.

  4. Capture the Image

    • Observe the thermal image on the display. You can often capture and save images for further analysis.

  5. Interpret the Results

    • Analyze the thermal image to identify any temperature anomalies. Different colors or shades represent different temperatures.

  6. Documentation

    • Save and document the thermal images and findings. Many thermal imagers have built-in storage or connectivity options for easy data transfer.
                   



Example: Electrical Panel Inspection

Objective: Identify potential hot spots in an electrical panel.

Steps:

  1. Safety First: Ensure all safety protocols are followed. Wear appropriate PPE.

  2. Power On: Turn on the thermal imager gun.

  3. Settings: Adjust the emissivity to match the surface of the electrical components (typically around 0.95 for electrical components).

  4. Scan the Panel: Aim the thermal imager at the electrical panel and scan from a safe distance.

  5. Capture Image: Identify any hot spots by looking for areas that are significantly warmer than others.

  6. Analyze: Investigate the cause of any hot spots, which could indicate loose connections, overloaded circuits, or failing components.

  7. Document: Save the thermal images and note the locations of any hot spots for follow-up maintenance.

Advantages of Thermal Imager Guns

  1. Non-Contact Measurement: Allows for temperature measurement from a distance, enhancing safety.

  2. Visual Diagnosis: Provides a visual representation of temperature distribution, making it easier to identify issues.

  3. Efficiency: Quickly scans large areas and identifies problems that might not be visible to the naked eye.

  4. Versatility: Can be used in various applications across different industries.

Conclusion

Thermal imager guns are powerful tools for detecting and diagnosing thermal anomalies in a wide range of applications. By converting infrared radiation into visible thermal images, they provide valuable insights that help in preventive maintenance, safety, and efficiency improvements. Proper use and interpretation of thermal images can lead to early detection of issues, reducing downtime and enhancing operational reliability.




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