4 FM quick reads on infrared
1. Infrared Imaging: In-House Insights
This is Chris Matt, Managing Editor of Print & E-Media with Maintenance Solutions magazine. Today's tip is in-house infrared imaging.
A decade ago, managers who needed infrared surveys had to find a qualified vendor and pay a premium price. The manager accepted the materials the vendor called a report, tried to make sense of it, and hoped the electrical and mechanical technicians fixed the right component based on the results. Rechecking the survey's results meant calling back the vendor and writing another check.
The entire process was out of the manager's control, and it cost a bundle. Not anymore. Contractors who provide infrared-imaging services remain valuable assets, given the experience they gained in using the technology. But instead of being simply bystanders, managers now participate in and control the process. Many departments have thermographers who handle infrared imaging in-house, making it easier for managers to incorporate infrared technology into their maintenance programs.
Advances in technology now make it possible for the value of infrared thermography to penetrate much deeper into departments and their activities than ever before. The impact of infrared imaging is similar to that of computerized maintenance management systems (CMMS), which have made tracking asset data much easier in recent years. Instead of pulling a dusty binder from a shelf, a manager can open a CMMS database and review inspections, verify technicians have made repairs, and even determine if technicians have conducted post-repair inspections.
Software for infrared-imaging systems also has evolved greatly. Analysis now can consist of multiple temperature data points within one image, overlay of isotherm palettes to highlight bands of temperature, and correction factors for surface emissivity and reflected background temperature.
These changes mean the information contained in a report gives managers more insight and value.
2. Infrared Imaging: Debunking Misconceptions
This is Chris Matt, Managing Editor of Print & E-Media with Maintenance Solutions magazine. Today's tip is understanding the benefits and debunking the misconceptions of infrared thermography.
Institutional and commercial facilities are reaping the benefits of using infrared thermography as part of their maintenance programs. Many are realizing significant returns in the form of increased equipment uptime, improved technician productivity, and lower maintenance costs.
For electrical systems, thermal imaging can reveal if the problem is a high-resistance connection or an overload in a circuit. Infrared imaging of mechanical systems can clearly show impending failures, from overheating motors to bad bearings. The process gives maintenance and engineering managers valuable data they can use to bring greater efficiencies and value to their inspection and maintenance programs.
As with any tool or technology, though, misconceptions persist regarding the results thermal imaging can, and cannot, produce. Managers considering either adding the technology or expanding existing programs need to consider several important items related to infrared thermography before making final decisions.
Some managers have invested in infrared-imaging programs based on the technology's supposed ability to measure temperature. In fact, infrared cameras — including spot radiometers — detect infrared radiation an object's surface emits and infers a temperature value from it. This process can lead to inaccurate readings, due to the laws of physics, incorrect camera settings, and untrained operators.
Despite commonly held beliefs, technicians cannot achieve accurate temperatures simply by adjusting the camera's emissivity correction value. This situation can get thermographers in trouble. While it usually is possible to make measurement parameter corrections for high-emissivity surfaces — such as rubber insulation on a wire or a painted, metal surface — measurements of shiny, metallic surfaces are unreliable, at best. Measuring temperatures might seem useful, but it is not the easiest application of the technology.
3. The Three Types of Infrared Cameras
This is Chris Matt, Associate Editor of Maintenance Solutions magazine. Today’s tip is better understanding the different types of infrared cameras.
Among the most powerful tools technicians have for holding down energy costs and detecting potential problems – both large and small – are infrared cameras. Infrared cameras come in three basic types: short wavelength, mid-wavelength, and long wavelength.
Short-wavelength infrared cameras typically detect infrared wavelengths in the spectral range of 0.9 to 1.7 microns, which is very close to the visible light spectrum. This type of camera delivers very high resolution, relative to the visible light spectrum in its shadow contrast and detail.
Mid-wavelength cameras typically detect infrared wavelengths in the spectral range of 2 to 5 microns, and they deliver higher resolution with accurate readings. The images are not as detailed as those produced by long wavelength cameras, due to an increased amount of atmospheric absorption within this spectral range. Cameras in this range are used for extreme high-temperature readings, such as scanning boiler applications and ballasted, single-ply roofing systems.
Long-wavelength cameras — the most widely used infrared camera — typically detect infrared wavelengths in the range of 7 to 12 microns. Cameras operating in this spectral range provide a great deal of detail because atmospheric absorption is minimal. Both long- and mid-wavelength cameras provide accurate temperature measurements and can produce detailed differences across small or large temperature ranges.
4. What Makes a Cool Roof Cool
Today’s tip is about the properties that govern how cool a cool roof is. Now that summer is upon us, and facilities are enduring the long, hot days that require lots of cooling energy, a cool roof can be a key part of facility executive’s energy reduction plan.
The two principles at work on a cool roof are infrared reflectance and thermal emittance. Infrared reflectance means the roof’s ability to reflect a portion of the sun’s infrared radiation – the part of the solar spectrum most responsible for heat gain. Some pure white cool roofs have infrared reflectances as high as 80 percent. That’s very good. But the key here is that the roof must be clean. Especially in big cities, where cool roofs have the most benefit because of the urban heat island effect, the smog and other city-related crud can collect on a roof and darken it. To get the maximum benefit of a roof, it should be kept as clean and white as possible.
The other value is thermal emittance, or a roof’s ability to reradiate energy that has been absorbed back into the atmosphere. In hot climates and during hot summer a months, roofs with high thermal emittance are good because they also prevent
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