Temperature is one of the important parameters to tell the condition of internal process, material and even quality of the desired output. A qualitative but accurate conclusion can be drawn by observing the temperature profile of any surface. On the other hand higher temperature also indicates obvious loss of energy in the form of heat. Therefore temperature monitoring would give ample indication of the condition of the material, process quality and explore the possibility of energy conservation avenues.
With the on-line condition monitoring technology becoming an inevitable part of maintenance strategy in today?s scenario, non-contact type temperature monitoring methods have become more popular. Infrared Thermography is such a non-contact type technique which provides a fast, reliable and accurate temperature profile of any material surface.
Thermography is nothing but the temperature profiling of a surface or point. As the name suggests, infrared thermography is based on Infrared(IR) technique. The principle underlying this technique is that every object emits certain amount of IR energy and the intensity of this IR radiation is a function of temperature. In an electromagnetic spectrum the IR region appears between 0.8 micron to 1000 micron wavelength (See Figure 1). This wavelength of IR spectrum is more than that of a visible spectrum. The IR energy which can directly represent the surface temperature can be detected and quantified by the help of IR scanning system.
A thermography instrument can be a thermal pointer or a thermal scanner. The thermal pointer reads the temperature of a specific dimensional point where as a scanner maps the thermal profile of an area surface.
The basic IR system consists of an ?IR energy detector? and a ?Monitor?. The scanner is an optomechanical device which converts the IR energy received from an object surface to an electrical signal. These signals are further fed into the monitor where it is processed and presented in many forms like simple digital display to indicate temperature level and a video display for thermal profile
Described below are some of the application areas of IR thermography with illustration of some real life case examples.
Infrared Predictive Maintenance (IR/PM) activities, especially as they relate to predicting electrical/mechanical systems equipment failure, are increasing in popularity. This is in no small part due to the efforts of the IR industry to educate engineering and maintenance department managers as to the advantages of predicting, and subsequently preventing, problems from becoming system failures by using infrared thermographic equipment and/or contract services. However, many companies and plants have failed to achieve what they really need: An extensive and effective Infrared Predictive Maintenance Program. One "Hot Spot" survey per year does not make a successful infrared program. The annual survey of equipment, regardless of whether the imaging is performed by a contractor or by an in-house group, should only be a part of the program. For a program to be effective it must be accepted by management as well as other maintenance personnel. Getting other maintenance people involved in Infrared Thermography is a good way of gaining acceptance not to mention the fact that, more people scanning equipment will find more problems, more quickly, resulting in payback more quickly for the plant. This paper discusses the approach which I am implementing with varying degrees of success at my client's plant sites and which could be implemented in plants with existing IR imagers. In the past, I have considered my services a very valuable part of my client's maintenance activities. They have obviously concurred, since I have returned to their facilities year after year. However, when I left a site, I was leaving with the only means of performing infrared testing. Now, I see my role changing. My goal as an infrared thermographer is to report potential problems on their critical electrical/mechanical systems prior to failure in a timely and cost-effective manner. However, there are two problems:
1) I do not inspect everything that needs to be inspected. While performing infrared surveys, we literally walk past hundreds of pieces of equipment that are in different stages of failure. But, we have been given a limited number of hours or days to check critical systems, so we pass by this equipment.
2) There is nothing remedial about infrared thermography itself. Sometimes repairs are either not made or not correctly made. In some facilities I report the same problems or types of problems on the same pieces of equipment year after year. To address these two issues, I have set out to provide my clients with what they need: The start of (or at very least the chance to start) an effective IRIPM Program where my services are a part of the overall program, but not the program itself.
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