Thermography

Thermography_______________________________________________________________ Thermography, thermal imaging, or thermal video, is a type of infrared imaging. Thermographic cameras detect radiation in the infrared range of the electromagnetic spectrum (roughly 900–14,000 nanometers or 0.9–14 µm) and produce images of that radiation. Since infrared radiation is emitted by all objects based on their temperatures, according to the black body radiation law, thermography makes it possible to "see" one's environment with or without visible illumination. The amount of radiation emitted by an object increases with temperature, therefore thermography allows one to see variations in temperature (hence the name).
When viewed by thermographic camera, warm objects stand out well against cooler backgrounds; humans and other warm-blooded animals become easily visible against the environment, day or night. As a result, thermography's extensive use can historically be ascribed to the military and security services.
	Thermal imaging photography finds many other uses. For example, firefighters use it to see through smoke, find persons, and localize the base of a fire. With thermal imaging, power lines maintenance technicians locate overheating joints and parts, a telltale sign of their failure, to eliminate potential hazards. Where thermal insulation becomes faulty, building construction technicians can see heat leaks to improve the efficiencies of cooling or heating air-conditioning. Thermal imaging cameras are also installed in some luxury cars to aid the driver, the first being the 2000 Cadillac DeVille.
Some physiological activities, particularly responses, in human beings and other warm-blooded animals can also be monitored with thermographic imaging.
The appearance and operation of a modern thermographic camera is often similar to a camcorder. Enabling the user to see in the infrared spectrum is a function so useful that ability to record their output is often optional. A recording module is therefore not always built-in.
Instead of CCD sensors, most thermal imaging cameras use CMOS Focal Plane Array (FPA). The most common types are InSb, InGaAs, QWIP FPA. The newest technologies are using low cost and uncooled microbolometers FPA sensors. Their resolution is considerably lower than of optical cameras, mostly 160x120 or 320x240 pixels, up to 640x512 for the most expensive models. Thermographic cameras are much more expensive than their visible-spectrum counterparts, and higher-end models are often export-restricted. Older bolometers or more sensitive models as InSB require cryogenic cooling, usually by a miniature Stirling cycle refrigerator or liquid nitrogen.
Advantages of Thermography
* You get a visual picture so that you can compare temperatures over a large area * It is real time capable of catching moving targets * Able to find deteriorating components prior to failure * Measurement in areas inaccessible or hazardous for other methods Benefits * Reduction of production losses due to unplanned downtime * Reduced maintenance and repair costs * Increased equipment life * Increased Mean-Time-Between-Failures (MTBF) * Increased productivity and profitability * Reduced insurance premiums Applications * Condition monitoring * Medical imaging * Research * Process control * Non destructive testing Thermal infrared imagers convert the energy in the infrared wavelength into a visible light video display. All objects above 0 degrees Kelvin emit thermal infrared energy so thermal imagers can passively see all objects regardless of ambient light. However, most thermal imagers only see objects warmer than -50C The spectrum and amount of thermal radiation depend strongly on an object's surface temperature. This makes it possible for a thermal camera to display an object's temperature. However, other factors also influence the radiation, which limits the accuracy of this technique. For example, the radiation depends not only on the temperature of the object, but is also a function of the emissivity of the object. Also, radiation also originates from the surroundings and is reflected in the object, and the radiation from the object and the reflected radiation will also be influenced by the absorption of the atmosphere. Thermography in Medicine Many of you who are more alternative minded may have heard of thermography. I’d like to take this 000week to tell you a little bit about this wonderful technique and it’s many applications. In medical practice, thermography is the process of taking a snapshot of your skin temperature. With an infrared camera, a person snaps a picture of your skin surface and then aided by computers, a digital picture of the varying skin temperature is seen. It looks a bit like a cartoon, but is an extremely useful technology for assessing abnormalities in skin temperature. Your thermograph is almost like your fingerprint. It does not change over time, yet it is a dynamic (flowing) way to assess your health. Why have one done, you might ask? Because of the body’s symmetry, the skin temperature should not vary from the left hand to the right hand, or the left breast to the right breast for example unless there is a problem. Indirectly, the thermogram is measuring the factors that affect blood flow to the skin surface and when the blood flow to one side of the body varies from that of the other. The factors that affect blood flow include growth proteins produced from tumors, blood clots, infection, and variations in the activity of the autonomic nervous system and a host of others. While thermography is not a diagnostic tool, it can certainly identify if there is an actual problem with blood flow and when used in conjunction with mammography, helps identify more tumors than the mammogram alone can. This technology is now being used in airports to determine if people are lying about what they take on board as well as identifying when their skin temperature is higher than normal thus identifying them as an “at risk” passenger to spread infection. There are over 8000 studies documenting the technology and benefits of thermography. Its application ranges from breast cancer and damaged nerves from a bulging disc to TMJ syndrome. One of the many advantages of thermography is its ability to identify breast abnormalities early. If you have a computer, go to our website, www.cfwellness.com and click on “skip intro”. This will take you to the next page of our site. There you will see two presentations on thermography. Click on “Breast Comparative” and you’ll see the thermograms of a young 37 year old woman who had no previous history of a breast abnormality. You can see that thermography identified a problem in her breast a full year before her mammograms did. While thermography is not a diagnostic tool (in other words it can’t tell you that the abnormality it identified is cancer), it is a very useful tool for identifying the genesis of the problem and for following it over time. When used in conjunction with other techniques, it aids in the early diagnosis of disease. Certification for thermography is done by the American College of Clinical Thermography at Duke University Medical Center. Our office offers full body or region of Interest (such as the breast, or face, etc) thermography. You may benefit from thermography if you are concerned about the following conditions: 1) Breast cancer 2) Fibrocystic breast disease 3) Blood clots 4) Bulging discs in your neck or back 5) Tempromandibular Joint Syndrome 6) Kidney infections 7) Liver problems 8) Reflex Sympathetic Dystrophy (RSD) 9) Thyroid nodules 10) Stress Fractures 11) Chronic arm or leg pain that has not been resolved. To see a more detailed list of conditions that may be more accurately assessed with thermography, go to: http://www.thermologyonline.org/patients_indications.htm PATIENT THERMOGRAPHY INFORMATION This information is being provided to assist you with your Thermography experience. Please adhere to the following protocols to insure the best possible results in your testing as there are many factors that can create false findings on the thermogram. PURPOSE: The purpose of the test is to detect recognizable signs of normal or abnormal physiological activity to determine if further clinical evaluation or preventive recommendations are required. PREPARATION: You will be trying to avoid activities that affect your circulation or body temperature as you prepare for the exam. Three months prior to exam: No major breast surgery, chemotherapy, radiation, lactation, or breastfeeding. One month prior to exam: No minor breast surgery or biopsy. One week prior to exam: Avoid tanning and/or sunburn 24 hours prior to exam: Avoid exercise, any cardiovascular workout of any kind, massage, acupuncture, chiropractic adjustment, physical therapy, steam rooms, saunas, hot or cold packs, hot tubs and shaving. If you have a fever, you will need to reschedule. Avoid alcohol and caffeine for 24-hours prior to your exam. Exam day: Do not shave underarms or legs if receiving a full body scan. Do not use any deodorant, antiperspirant, perfume, powders, cream or lotion on your upper body or under your arms. If receiving full-body scan, this applies to entire body. Avoid sun exposure – you cannot be sunburned. Two Hours prior to exam: Discontinue use of tobacco, caffeine, coffee, hot liquids, cold liquids, exercise, bathing, and showering. If an image of your head is being taken, do not eat or chew gum. DURING THE EXAM: All jewelry will need to be removed for the test. There will be no contact with your body, no injections, no radiation, no fluids to drink. You will be in a cool private room with the camera positioned four to seven feet from you. You will be asked to turn to the necessary positions. You will be required to disrobe all areas of the body to be imaged with the exception of underpants, which will remain on. A trained thermographer will be making the images. A single region of the body takes about 15 minutes, and the full body takes about 45 minutes. REPORTING: Your images and questionnaire will be forwarded to a trained thermologist for interpretation. You will receive a written report and images when the report is complete. A copy can be sent to your doctor with your written request. Please allow 2 weeks for your results. INTERPRETATION: The images are reviewed for certain temperature findings which may suggest elevated risk for disease. Thermal imaging provides information about current and future risk only and does not provide a diagnosis. Findings should be correlated with diagnostic examinations before a final diagnosis and treatment decision is made. Thermograms are not replacements for mammograms, but rather a different kind of tool for predicting disease. PORTABLE INFRARED CAMERAS FOR PLANT CONDITION MONITORING INTRODUCTION: The use of Infrared Thermograph to evaluate the operating condition of electrical, mechanical and process equipment for early warning signs of impending failure has increased dramatically over the past few years. The industry is forecast to continue growing at unprecedented rates, driven by the following catalysts: ü Market Awareness and Acceptance – More information and articles are being printed worldwide on this technology than every before. ü Application Diversity – No other technology has the diversity of infrared thermography. It is used to inspect electrical and mechanical equipment, to detect leaks in underground pipes, subsurface metal corrosion, insulation deficiencies, building energy loss and roof moisture intrusion. It is also used in medicine and for process monitoring and control of a wide range of processes. New applications are continually being found. ü Equipment – The equipment is more compact, it is easier to use, it provides better imagery, faster analysis and uses software that allows reports to be written easily. Prices are also continually dropping. ü Standards – Standards for thermography are beginning to come out (ASNT, ASTM, ISO) which means that it is gaining recognition and credibility. For example, inCanada, USA and Norway most companies are requesting that thermographers have a Level I status to perform infrared thermography inspections. ü Training – Training, educational programs and seminars are now available at locations throughout the world. INFRARED THERMOGRAPHY Temperature is one of the first observable physical parameters that will indicate the operating condition of a component or equipment, and is by far the most measured Quantity in an industrial environment. For this reason, monitoring the thermal operating Condition of electrical, mechanical or process equipment is considered to be the key to any condition monitoring program. Infrared thermography is a condition monitoring technique used to remotely gather thermal information from any object or area, converting it to a visual image. Infrared cameras provide the means for which trained and qualified technicians can examine the temperature distribution of plant equipment. Once a problem is identified a decision is made based on the operating condition of equipment, to either resolve the problem immediately, or continue to monitor the condition The latter may involve using another monitoring technique to provide additional information. Infrared condition monitoring techniques offer an objective way of assessing the condition of plant equipment in order to predict the need for maintenance. BENEFITS OF THERMOGRAPHY This technology is used independently or in conjunction with other condition monitoring techniques and test equipment. Benefits include reduced down time, lower maintenance costs, higher equipment and process availability and increased performance. A key benefit of the technology is the speed at which existing, new or recently repaired equipment can be inspected and problems diagnosed. This in turn maximizes availability. It can be applied to high risk equipment or processes, allowing them to be evaluated from a safe distance. Thermography also has the ability to generate information that can be used to improve equipment and enhance operational and process modifications. BRIGHT FUTURE FOR THERMOGRAPHY Whether you are considering becoming involved in thermography simply to help the company you work for, or are looking to set up an infrared service organization, there has never been a better time than the present. Market evaluation companies such as Frost & Sullivan, Maxtech International and Thomas Marketing Information Centre have all prepared market studies and surveys that look at infrared thermography. The results are similar and show that infrared thermography is an emerging technology that is coming into its own. “The total market is projected to experience a compound annual growth rate of 31% from 1996 to 2003.” APPLICATIONS Total maintenance costs range from 15 – 40 percent of the total cost of goods produced and is the single largest contributor to controllable cost in most manufacturing and process facilities. Infrared thermography has been identified as the most diversified condition monitoring technique available today and has the potential to be the greatest contributor to the reduction of maintenance and process related costs. No other technique offers the variety and quantity of applications, from the inspection of electrical components, bearings, fluid levels, and insulation deficiencies to metal thinning and corrosion. Areas where thermography has proven to be very useful are: ü Electrical equipment – including switches, fuses, transformers, motors, motor control centers, ballasts, overhead lines, bushings, and electronic boards. ü Mechanical applications – overheating bearings, couplings, pillow blocks, gears, belts, compressors, hydraulic systems, internal combustion engines, turbines, generators, valves, brakes, conveyors, and hvac systems. ü Process equipment – steam systems, heat exchangers, storage vessels, boiler casing leakage, vacuum leaks, tank levels and sludge build-up, piping insulation and leaks, leaks in buried lines, product control and furnaces (both interior and exterior), furnace tubes and refractory. ü Buildings – insulation, moisture, air leakage, flat roof leaks, concrete, hvac, refrigeration systems. ü Firefighting, search and rescue, security, safety ü Environmental applications – oil/gas leaks, oil spills on land and water, finding buried storage tanks, thermal/chemical pollution into waterways. ü Other applications include locating leaks and problems in steam systems, piping and steam traps, UPS systems for dead battery cells, poor connections and diesel generator problems, metal applications such as thinning subsurface corrosion, weld integrity and robot welding equipment evaluation. SIGNIFICANT ADVANCES Infrared camera technology has advanced significantly since the early 1960’s when Swedish company, AGA introduced the first commercially available infrared imaging instrument. Early instruments were heavy and bulky, they required liquid nitrogen to operate, they provided black and white fuzzy images and offered only relative temperature measurement that required the use of long and complex formulae. Infrared imagers fall into three categories. Electromechanically Scanned Instruments collect and direct the incoming infrared radiation onto a single detector element, or linear array, by means of rotating or oscillating prisms or mirrors. They Pyroelectric Videcon Imager, the second type, uses a pyroelectric surface detector, which after being aimed at the target, develops a charge distribution that is proportional to the target’s radiant energy. The infrared focal plane array (IRFPA) camera, the third design, makes use of a high density mosaic of small detector elements, which are aimed at the target. Each element “sees” a single infrared pixel of the target, and no mechanically scanned optics are required. The size of they array ranges from a matrix of 128 horizontal elements by 128 vertical elements to one that contains 512 x 512 elements. These instruments are classified as “staring” systems in contrast to opto-mechanical “scanning” infrared devices. The greatest single benefit of an FPA is its ability to generate high quality images (Figure 1). In mechanically scanned single-element detectors, 14,000 to 26,000 picture elements make up the field-of-view. An FPA covering the same field-of-view will comprise 65,000 to 262,000 pixels. This means the FPA will have 3 – 10 times more image detail. An image with higher resolution allows problems to be identified without the camera operator having to change lenses, it enhances analysis procedures and it provides an image that is easier to read and understand. The FPA detector may be a significant breakthrough in technology but without advancements in the optics, electronics and microprocessor technology it would not have been the possible to develop these cameras. The interaction between these components is important and it determines the diversity and quality of the instruments available today. FUTURE DEVELOPMENTS Clearly, uncooled infrared FPA’s represent a revolution in infrared instrumentation. The uncooled microbolometer technology has dramatically changed the industry and has helped create a number of opportunities for thermal imaging. It is expected that the technology will continue to develop particularly in the area of improved detectorperformance and reduced Noise Equivalent Temperature Difference (NETD) and electronics. As costs continue to decrease and production volumes rise, the price of solid state uncooled, lightweight systems should drop significantly. Expect to see larger arrays (640x 480) and smaller, lightweight instruments using less power. There is a movement now into a new semiconductor based IRFPA detector technology, Quantum Well Infrared Photodetector (QWIP). The interest in this technology is that it promises major advances for infrared focal plane arrays: ü Excellent pixel uniformity, imaging and sensitivity performance. ü Large pixel format capability, up to 640 x 480 ü QWIPs are tunable and can be made responsive from about 3 to 25 microns, can be made for broad band and dual band applications. ü Can be produced at relatively low cost and in large quantities. The simplicity, flexibility, high performance and low cost will guarantee the development of this technology.Initially, this technology will be used for military, surveillance and process monitoring and control, but, watch this technology as it is going to be a very interesting one. The interaction between these components is important and it determines the diversity and quality of the instruments available today. Figure 1 - The image resolution of the two FPA images (right) are clearly superior to the single element detector image (left), making identification and analysis easier. INFRARED PROGRAM In order to profit from the benefits of infrared thermography, regardless of the technology chosen, much consideration should be given to establishing an infrared inspection program. One that is properly initiated is guaranteed to provide users with a quick return on investment. Typically this will occur within 3 months of purchasing and using the equipment, but many companies claim receiving a payback the very first day on which they performed an infrared inspection. The first of several steps in setting up a successful thermography program is: Education: The very first step is to find out some more about the products and technology that are available and how they can be used. ü Go to introductory seminars and conferences. ü Request product data sheets and application literature from equipment vendors . ü Browse the internet. This is a little time consuming, but there is a wealth of information on the web. ü Contract in an independent consultant to assist in the assessment and education process. ü Hire an experienced infrared service company and learn from their employees while they are performing an inspection in the field. ü Take a training course before you purchase your instrument. This will provide you with an understanding of the IR industry and technology, equipment and application knowledge, and allow you to gain valuable experience from the instructors and other students. You will also then be prepared to deal with and negotiate efficiently with the instrument sales reps. Make sure you go to independent training companies for this training, the vendors will be very biased in their course towards their products. CONCLUSION Although the methodology used to implement and purchase equipment, and program requirements vary from plant to plant or from person to person, the following key observations set out here should be helpful. Select an instrument that will make inspections successful, now and in the future. An IR camera is a diverse tool and, when deciding on a particular type, also take into account as much as possible, your future requirements. Plan the implementation phase carefully. Decisions on how to collect and manage data should be made at the outset, and should focus on the desired output of the program. This planning will both simplify implementation and maximize the value of the program.