2013
Using Tmax Corrected Formula to Prioritize Electrical Exceptions
Tip written by: Infraspection Institute
For decades, temperature measurement has been used to gauge the operating condition of electrical components. With this Tip, we explore an alternative to the traditional Delta T method of prioritizing exceptions during infrared inspections of electrical distribution systems.
Thermographers have long used temperature differentials or Delta T measurements as a means of prioritizing electrical exceptions. Typically, Delta T values are calculated by comparing the temperature of an exception to similar components under similar load or to ambient air temperature. Although they work well in many circumstances, Delta T readings are not applicable for components that do not qualitatively manifest themselves as an exception.
An alternative to Delta T calculations is a formula known as Tmax Corrected. This formula is based upon an IEEE formula and calculates pass/fail criteria based upon several factors including equipment type, ambient air temperature, and circuit load. The Tmax Corrected formula looks like this:
TmaxCorr = {(A meas ÷ A rated )2 (T rated rise)} + Ambient
Where:
- Tmax Corr = corrected maximum allowable temperature
- A meas = measured load, in amperes
- A rated = rated load, in amperes
- T rated rise = rated temp rise for component
- Ambient = measured ambient temp
It should be noted that the exponent can vary between 1.6 to 2.0. In this illustration, we have shown an exponent of 2 for simplicity.
Despite taking a little more time to apply than Delta T calculations, Tmax Corrected allows one to determine if a component of interest is running within specification for any load or ambient temperature. Tmax Corrected is especially useful for equipment that is not manifesting itself as an exception. In particular, Tmax Corrected can be an invaluable tool for those who perform infrared inspections as part of commissioning studies or use thermography for acceptance testing of new installations, repairs, or retrofits.
Proper use of the Tmax Corrected formula is just one of the many topics covered in all Infraspection Institute Level II Certified Infrared Thermographer® training courses. The proper application of Tmax Corrected along with a comprehensive table of rated temperature rises is also detailed in the Standard for Infrared Inspection of Electrical Systems and Rotating Equipment. Copies of this Standard may be purchased by calling 609-239-4788 or through the Infraspection Online Store.
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How Much Certification Do You Need
Tip written by: Infraspection Institute
Certification and levels thereof are one of the most frequently discussed issues in thermography. With few standards addressing certification, purchasers of infrared inspection services and thermographers often ask, “How much certification is necessary?”
Due to a variety of definitions, certification can have different meanings. As it is used in thermography, certification generally means, “to declare something to be true and/or to attest by issuing a certificate to.”
The American Society for Nondestructive Testing document, SNT-TC-1A provides suggested curricula and experience for under the Thermal/Infrared test method. Recommended curricula and the classroom hours are listed below; these should be modified to meet an employer’s needs.
In short, it is up to an employer to determine his/her client’s needs for and to set certification requirements accordingly.
Taken at face value, certification generally indicates one’s level of formal training. This training, combined with experience and knowledge of the system or structure being inspected determine a thermographer’s qualifications.
In a larger sense, certification is a measure of a thermographer’s professional qualifications. It is therefore incumbent on the professional thermographer to achieve the highest level of certification possible. The rewards for doing so are both personal and professional and can provide significant financial and competitive advantages.
Infraspection Institute has been training and certifying professional infrared thermographers since 1980. Our Level I, II, and III Certified Infrared Thermographer® training courses are fully compliant with ASNT and industry standards. Students may choose from open-enrollment and convenient web-based Distance Learning Courses. For more information or to register for a class, call 609-239-4788 or visit us online at www.infraspection.com.
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Determining Maximum Operating Temperature for Motors
Tip written by: Infraspection Institute
Operating temperature can have a significant impact on the service life of operating electric motors. Accurately determining maximum operating temperature for motors is critical for setting temperature limits.
One of the specifications for electric motors is maximum operating temperature. This temperature value is determined by several factors including, but not limited to, the motor’s insulation class. Exceeding the maximum temperature for a motor will shorten the life of the motor’s dielectric materials and will result in decreased service life for the motor.
In order to calculate a motor’s maximum rated temperature, one must know the motor’s ambient temperature rating and its rated temperature rise above ambient. Both of these values are generally found on the motor nameplate located on the exterior of the motor casing.
To calculate a motor’s maximum operating temperature, add the ambient and rated rise temperatures. Their sum is the maximum operating temperature for the subject motor at 100% load.
Example:
- Rated Ambient: 40 C
- Rated Rise: 90 C
- 40 + 90 = 130 C or 266 F
It is important to note that some motors specify insulation class rather than a numeric value for temperature rise. In such cases, it is necessary to know the operating limits for the insulation class of the subject motor.
The Infraspection Institute Standard for Infrared Inspections of Electrical Systems & Rotating Equipment provides temperature limits for several common insulation classes of AC and DC motors. In addition to providing inspection procedures, it also provides temperature limit data for lubricants, bearings and seals. To order a copy of the Standard, call 609-239-4788 or visit the Infraspection online store.
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Heat Stress & Hydration
Tip written by: Infraspection Institute
An ounce of prevention is worth a pound of cure. In last week’s Tip, we covered the topic of heat stress, its symptoms, and treatment. This Tip focuses on the importance of hydration as a preventive measure.
What is heat stress?
Heat stress is a physical hazard. It is caused by environmental conditions and results in the breakdown of the human thermal regulating system. If you work or play in hot environments, your body needs a lot more water than you might think.
What is hydration?
Hydration is the process of adding water. Our bodies need water to do many things. In hot environments we need large quantities of water to help keep our bodies cooled to a temperature that allows them to function properly. Heat stress becomes a health and safety concern when the volume of water we need to function drops below the level necessary to maintain homeostasis. We call this low water condition dehydration or under-hydration. The average person is 7% under-hydrated.
How can I avoid being under-hydrated?
Developing the habit of drinking water at routine intervals. One 8 oz. cup every hour on hot days will assure proper hydration.
How will I know if I am properly hydrated?
Check the color of your urine. You are properly hydrated if your urine is clear, copious in volume, and light yellow in color.
What are the benefits of proper hydration?
Staying properly hydrated will help to avoid heat stress and may increase your energy level. For every 1% under-hydration, you lose 5% of your energy potential.
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Insurance for Thermographers
Tip written by: Infraspection Institute
As thermography gains wider acceptance, the number of firms offering infrared inspections continues to grow. A common challenge among thermographers is obtaining appropriate insurance coverage for their inspection activities.
Insurance is a necessary expense in the modern business world. Depending upon a where a business is located, certain types of insurance (unemployment, automobile, workers compensation) and the amount of coverage may be mandated by law. General liability insurance which is designed to protect against an insured against a legal claim often evokes the greatest number of questions.
For professional thermographers, the challenge in obtaining the correct type of insurance and the amount of coverage will depend upon several factors. These include, but are not limited to, the location where work is to be performed, the types of inspections to be conducted, thermographer training and experience, and the content of any reports to be issued.
In order to best determine insurance needs, a thermographer should consult with their insurance broker or agent who can provide the best guidance on insurance options. In the absence of a current insurance professional, consider asking for a referral from another local business. When seeking insurance, consulting with more than one insurance professional will likely provide both policy and pricing options.
Infraspection has been training and certifying thermographers for over 25 years. Since 1983, our Certified Infrared Thermographer® program has been setting the standard for excellence among professional thermographers worldwide. For information on training courses and certification, contact Infraspection Institute at 609-239-4788 or visit www.infraspection.com.
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Understanding Emissivity
Tip written by: Infraspection Institute
Emissivity refers to an object’s ability to radiate infrared energy. Because infrared instruments measure radiant energy, it is imperative for a thermographer to understand emissivity and how it can vary.
All objects above 0 Kelvin radiate infrared energy. The amount of energy radiated is dependent upon an object’s temperature and emittance. Increases in temperature and/or emittance will increase the amount of infrared energy radiated.
Although many equate emissivity to values published in emittance tables, emissivity is a dynamic characteristic and is influenced by several factors. Among these are:
Wavelength – For most objects, emissivity varies with wavelength.
Object Temperature – Changes in object temperature cause changes in Emissivity
For clean metals, E increases with temperature rise
For dielectrics, E decreases with temperature rise
Viewing Angle – Imaging at angles other than perpendicular causes changes in Emissivity
Target Geometry – Target shape affects Emissivity. Compared to a flat surface,
Concave shape increases E
Convex shape decreases E
Surface Condition – Surface roughness, texture, or condition (dirt, oxidation or paint) can significantly affect Emissivity
Although thermographers frequently obtain emittance values from published tables, this practice can introduce significant temperature measurement errors since emittance tables cannot account for several of the above factors. Because of this, calculating emittance with one’s thermal imager will help to ensure measurement accuracy.
A simple procedure for calculating emittance may be found in the Standard for Measuring and Compensating for Emittance Using Infrared Imaging Radiometers. To order a copy of this or other standards, call Infraspection Institute at 609-239-4788 or visit the Infraspection Online Store.
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From the Top Down
Tip written by: Infraspection Institute
“From the top down” describes an approach for managing companies. It may also describe an effective way to perform infrared inspections.
During the performance of infrared inspections of electro/mechanical equipment in high-rise facilities, efficiently moving between floors can be a challenge. Waiting for elevators can be especially time consuming; climbing stairs with tools and instruments can be physically taxing.
One solution is to begin the infrared inspection at the uppermost floor or roof level. Upon completing the inspection of all equipment on the subject floor, proceed to the next lower floor via the stairwell. Doing so usually requires less than a minute, compared to the lengthy wait often required to catch an elevator.
- When using stairways to move between floors, make certain that:
- Affected personnel are notified of the inspection activities
- Inspectors have keys or doorway lock combinations to enter occupied spaces from the stairwell
- Fire/security alarms will not be tripped whn moving into or out of stairwells
- Tripping hazards are not created by test equipment or tools
Infrared inspections of power distribution systems is one of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. For information on thermographer training including course locations and dates, visit us online at www.infraspection.com or call us at 609-239-4788.
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Flame Resistant Clothing
Tip written by: Infraspection Institute
Flame Resistant Clothing is required Personal Protective Equipment for many who work in high temperature areas or near energized electrical equipment. If your job requires the use of FRC, there are several important things of which you should be aware.
Not all garments classified as FRC are created equal. When choosing FRC you should be aware that:
- FRC is not fireproof. It is designed to protect the wearer from burns by resisting ignition during brief periods of high temperature exposure such as electrical arc flashes.
- FRC is manufactured with different materials and different weights. Be certain that the chosen material is appropriate for the task at hand.
- FRC effectiveness can be compromised by age, wear, contamination with flammable materials and the attachment of name patches or embroidery. FRC can be permanently damaged by improper cleaning or laundering.
- FRC provides protection from thermal burns. It does not provide protection against other hazardous forces such as flying debris, electric shock, or the supersonic blast wave that may be associated with arc flash incidents.FRC is only effective when it is worn properly. It should always be worn as the outer-most garment. If worn over other layers clothing, the undergarments should be made of natural fiber and completely covered by the FRC.
Before wearing FRC, be certain to understand its proper application and limitations and how to use it properly. As always, remember to work safely!Safety is one of the many topics covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. For more information or to register for a course visit us online at www.infraspection.com or call us at 609-239-4788.Visit Infraspection Institute Web Site
Infrared Inspections of Retrofitted Roofs
Tip written by: Infraspection InstituteIf your roof has been retrofitted with a new roof installed over an existing one, it is imperative that you test the roofing system for water infiltration at least annually. With limited opportunity for egress, water entering the upper roof of a retrofitted system can cause widespread damage in a very short period of time. To make matters worse, there is usually no visual evidence of this type of a leak from inside of the building.
Performed in conjunction with regular visual inspections of your roof, infrared inspections of low slope roofs are a very cost effective way of tracking the overall health of your facility’s roofing system. Locating leaking areas while they are small allows them to be addressed before they can spread. Additionally, moisture trapped within a roofing system almost never dries out and can cause premature failure of the roofing membrane, adhesives, fasteners, and the roof deck.
Whether you choose to have an in-house thermography team or an outside contractor perform the inspection, make certain that the Thermographer is both Certified and experienced. Since an infrared imager cannot confirm moisture presence, all infrared data must be verified by invasive testing as well.
Infrared inspection of flat roofs is one of the many topics covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. For more information or to register for a course, visit Infraspection Institute or call us at 609-239-4788.
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September 02, 2013
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Infrared Inspections of Retrofitted Roofs
Tip written by: Infraspection InstituteFor many areas, September is a month of transition – cooler weather, leaves turning color, and children returning to school. In this Tip we offer some advice for keeping school students safe.
Over 56 million students are projected to be enrolled in U.S. schools this fall; over 70 percent will be under 15 years old. According to the National Highway Traffic Administration, one-fifth of all children 14 years of age and younger who die in motor vehicle crashes are pedestrians. On average, one pedestrian is killed in the United States every two hours.
Morning can be a dangerous time for children, as they travel to the bus stop, ride their bike to school or walk along their routine path. Afternoon introduces additional risks as the ring of the final bell marks the sound of freedom for school-age children. Unfortunately, children are often distracted by thoughts of playtime or are unable to accurately judge traffic situations while on their journey home.
Keeping the following in mind can help protect everyone’s safety:- Slow down in or near school and residential areas.
- Drive with your headlights on – even during the day – so children and other drivers can see you.
- Look for clues such as School Safety Patrols, Adult Crossing Guards, bicycles, and playgrounds, which indicate children could be in the area.
- Always stop for school buses that are loading/unloading students.
- Limit distractions such as cell phones, CD players or other devices that cause you to take your eyes off the road.
- Practice extra caution in adverse weather conditions.
- Pay particular attention near schools during the morning and afternoon hours.
- Scan between parked cars and other objects for signs that children could dart into the road.
Remember, school’s open – drive carefully. You can make a difference just by staying alert and taking the extra care while driving where children are present. For more info on driving safety, contact the Mid-Atlantic AAA.
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September 09, 2013
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Autumn IR Inspections to Assess Roof Condition
Tip written by: Infraspection InstituteWith parts of the US experiencing record setting heat, it is hard to think about winter. For many, autumn provides a perfect opportunity to conduct infrared inspections of flat roofs to help ensure that they are ready for the upcoming colder months.
Summer can be especially tough on roofing systems. High temperatures, building movement, and UV radiation often cause cracks and splits in the waterproofing system. Left undetected, these cracks and splits can lead to roof leaks and premature roof failure. Performing an infrared roof inspection prior to the onset of colder weather can detect evidence of problems and help to direct repair efforts.
Performed under the proper conditions with the right equipment, an infrared inspection can detect evidence of latent moisture within the roofing system often before leaks become evident in the building. For many locations, autumn provides perfect conditions for conducting an infrared inspection and performing any necessary roof repairs.
The best candidates for infrared inspection are flat or low slope roofs where the insulation is located between the roof deck and the membrane and is in direct contact with the underside of the membrane. Applicable constructions are roofs with either smooth or gravel-surfaced, built-up or single-ply membranes. If gravel is present, it should be less than ½” in diameter and less than 1” thick.
For smooth-surfaced roofs, a short wave (2-5.6 µ) imager will provide more accurate results especially if the roof is painted with a reflective coating. All infrared data should be verified by a qualified roofing professional via core sampling or invasive moisture meter readings.
Infrared inspection of flat roofs and proper equipment selection are two of the many topics covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. For more information or to register for a course, visit Infraspection Institute or call us at 609-239-4788.
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September 16, 2013
Sponsored by:Get Your Website Seen
Tip written by: Oliver Beauchemin
Accolade Group of Vermont, LLC – www.accoladegroup.comEver since Google became the number one search engine, companies and individuals have been trying to get them to recognize their website. So the experts have been giving website owners advice on how to accomplish this task for a few years. Unfortunately, the advice they are giving has not kept pace with the way Google decides if a website should be included in the search results, on what page of the search results it should appear, or, if the website should be ignored.
Here are a few tactics that have lost the favor they once held by Google and other search engines: links to your website, what comments you make about your website on blogs or forums, keywords.
Whoa! Keywords? They aren’t relevant? This correct. In fact, they haven’t been relevant for a number of years. By keywords we mean the words that are entered into the keywords metatag in the code that displays your website. The keyword metatag is passé. Now don’t go running off to delete all your keyword metatags; some search engines still look at them, just not Google.
So, here’s what does work with Google.
1. The URL of the webpage. If you can, it is helpful if the url of the webpage is closely related to the topic of the webpage. If the page is about cats, a good url would be www.domain.com/cats.html.
2. The Title metatag. In the codebehind your webpage, there is a place for you to give a Title to the page. Do this. Don’t overlook it. This is part of what Google will display if your website appears in the Search Engine Result Pages (SERPS). A good Title metatag would be “This webpage is about the history of cats.” Try to keep your Title metatag no more than 70 characters including spaces.
3. The Description metatag. This is also a most important metatag. What you write here will appear in the description of your webpage if Google decides to show your page in the SERPS. Here is a clear Description metatag: “The history of cats is amazing and you will want to read this with your cat.” About 150 characters including spaces; more characters and Google will display an ellipsis (…) instead of what you wrote.
4. H1 tags. H1 tags are headlines. In the code they look like this:
History of Cats.
The best place for an H1 tag is in a headline, larger font, above a paragraph of text. Think of them as headlines.
5. Content on the page. This is the most important element for having your webpage in the Google search engine. The entire webpage should be on a single topic. Start adding more topics and Google has difficulty determining what the webpage is about.
The content of the webpage should use words that clearly express what the webpage is about. Sound familiar? This is the current definition of KeyWords. Some good keywords for our example might be “cat”, “feline”, “history of cats”, “history of short hair cats”. However, do not overuse the keyword that you want Google to take notice of. Use the word too many times and Google will call it “keyword stuffing” and your page will be penalized. More than seven uses of a word begins to move into the “keyword stuffing” area.
The above tips are not all inclusive of what Google calls “signals” for a webpage. However, they are among the most relevant. Following the guidelines above will not guarantee you will be in the Google results but if you aren’t using them your success rate will be greatly diminished.
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September 23, 2013
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The Value of Level III Certification
Tip written by: Infraspection InstituteCertification is one of the most frequently cited credentials for practicing infrared thermographers. In this Tip we discuss the importance of Level III certification and why thermographers need to train and certify to the highest level possible.
The advent of lower priced equipment has created greater public awareness and a dramatic increase in infrared imager sales. Sales of imagers to contractors, service companies, engineers and consultants are at an all-time high. As a result, many areas have seen an increase in competition among those who provide professional infrared inspection services.
In addition to an increase in the number of firms providing infrared inspection services, many infrared consultants are often competing with poorly trained thermographers with little or no field experience. The following practices can help customers and prospects appreciate the true value of an experienced consultant and to level the playing field in competitive situations.
- Obtain quality training for all thermographers. Training should be from a recognized, independent training firm
- Implement a meaningful written practice for your thermography program. This simple step serves as a blueprint for an infrared inspection program and helps to ensure quality
- Emphasize thermographer field experience in addition to training. Clients often place value above low price and will spend more money for your services if they believe that you are better qualified than a lower priced competitor
Lastly, train and certify all thermographers to Level III. Training to minimal levels sends a poor message to clients and limits a thermographer’s knowledge base and revenue potential. Requiring Level III for all thermographers can provide a competitive advantage and increased profits.
Infraspection Institute has been training and certifying professional infrared thermographers since 1980. Our Level III Certified Infrared Thermographer® training course teaches the industry’s best practices and is fully compliant with ASNT and industry standards. Our highly experienced instructors provide up-to-date information vital to help maximize your program’s success and profits. For more information or to register for a class, call 609-239-4788 or visit us online at www.infraspection.com.
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September 30, 2013
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Point Radiometers & Spot Measurement Size
Tip written by: Infraspection InstituteWith awareness of infrared technology at an all time high, point radiometers have become a common tool in many areas. Frequently, knowledge of proper operation lags behind instrument popularity. Understanding how spot measurement size affects accuracy is imperative to collecting meaningful data.
All radiometers are limited by a characteristic known as spot measurement size or spot size, for short. Spot size is determined by a radiometer’s detector and optics. Typically, spot size increases as distance to the target is increased. For accurate temperature measurement, spot size must always be smaller than the target being measured. When using a point radiometer, be sure to keep the following in mind:
- Point radiometers are usually supplied with a Distance to Spot Ratio value. To determine spot size, divide distance to target by ratio value.
- Point radiometers have minimum focus distances. At lesser distances, spot size will not decrease.
- Single, laser-generated aiming dots do not represent spot size
- Multiple, laser-generated aiming circles/dots often understate spot size
- Beware of stated spot size ratio values. Spot size ratios are frequently quoted at 90% radiance (accuracy) or less
When using a point radiometer, be sure to understand the limits of your instrument and the challenges presented by your target. Always use correct emissivity values and stay within the limits of your instrument.
Spot measurement size and its effect on non-contact temperature measurement is just one of the many topics covered in all Infraspection Institute Level II Certified Infrared Thermographer® training courses. For more information on open enrollment classes or our Distance Learning opportunities, call 609-239-4788 or visit us online at www.infraspection.com.
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October 07, 2013
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IR Imaging for Checking Tank Levels
Tip written by: Infraspection InstituteFor many facilities, obtaining accurate product level information for tanks and silos is critical for effective inventory management and safety. Under the right conditions, a thermal imager can quickly indicate product levels and serve as a cross reference for calibrating level indicators.
When product is stored in a vessel, the density of the product is usually greater than the head space of air or gas above the stored product. For stored products that generate heat, levels may be observed by imaging the vessel’s exterior and noting the temperature gradient between head space and product.
For stored products that do not generate heat, it is possible to rely on solar loading to create a temperature differential. Under solar loading conditions, vessels will usually exhibit cooler temperatures above the product level during the early to mid-morning hours. As the day progresses, the head space will exceed product temperature and show as a warm area above the product. This thermal pattern may remain for up to several hours after sunset and reverses once the head space cools to below stored product temperature.
Thermogram shows relative height of liquid contained in a large
outdoor storage vessel. Image courtesy of www.imaging1.comIn general, this application works best for un-insulated, single-wall vessels having a high emittance. For vessels with a low emittance, it may be possible to modify the surface with a stripe of high emittance paint. This application also works best on storage vessels where product level is not subject to rapid changes.
Thermal imaging of storage tanks and silos is one of the many applications covered in the Level I Certified Infrared Thermographer® training course. For more information on open enrollment classes or our convenient, web-based Distance Learning program, call 609-239-4788 or visit us online at: www.infraspection.com.
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October 14, 2013
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Measuring and Compensating for Reflected Temperature – Part 1
Tip written by: Infraspection InstituteNon-contact thermometry provides a means for rapidly measuring object temperatures. To ensure measurement accuracy, all error sources must be considered and properly addressed. With this Tip, we discuss how to measure and compensate for Reflected Temperature using the Reflector Method.
Unlike contact thermometry, infrared temperature measurement is subject to several error sources. While many are familiar with emissivity, another common error source is reflectivity. In order to compensate for errors due to reflections, imaging and non-imaging radiometers have inputs for entering Reflected Temperature. Depending upon the make and model of the instrument, this control may be referred to as TAM, Ambient Temp, Background, or Reflected Temperature.
Since all real world objects have emittance values of less than 1.0, some infrared energy will always be reflected from a measured object’s surface. The Reflected Temperature feature found on radiometers will mathematically compensate for this error source provided that it has been properly set by the operator.
Listed below are the general steps for measuring and compensating for Reflected Temperature when using an imaging radiometer and a diffuse infrared reflector. A diffuse reflector can be made from a crumpled and re-flattened sheet of aluminum foil that has been wrapped around a piece of cardboard.
- Place imager at desired location and distance from object to be measured
- Aim and focus imager
- Place diffuse reflector in front of, and in same plane as, object’s surface
- With imager’s E control set to 1.0, measure apparent temperature of diffuse reflector
- Conduct procedure three times and average results
- Enter averaged value into radiometer’s Reflected Temperature input
When measuring Reflected Temperature, make certain to maintain a safe distance from any hot or energized targets and observe all necessary safety precautions. When entering Reflected Temperature into your radiometer, be sure to access the proper menu as some imagers have inputs for Reflected Temperature as well as ambient air temperature.
The above procedure is described in greater detail in the Standard for Measuring and Compensating for Reflected Temperature Using Infrared Imaging Radiometers. For more information on infrared standards or thermographer training, call 609-239-4788 or visit us online at www.infraspection.com.
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October 21, 2013
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Measuring and Compensating for Reflected Temperature – Part 2
Tip written by: Infraspection InstituteNon-contact thermometry provides a means for rapidly measuring object temperatures. To ensure measurement accuracy, all error sources must be considered and properly addressed. With this Tip, we discuss how to measure and compensate for Reflected Temperature using the Direct Method.
Unlike contact thermometry, infrared temperature measurement is subject to several error sources. While many are familiar with emissivity, another common error source is reflectivity. In order to compensate for errors due to reflections, imaging and non-imaging radiometers have inputs for entering Reflected Temperature. Depending upon the make and model of the instrument, this control may be referred to as TAM, Ambient Temp, Background, or Reflected Temperature.
Since all real world objects have emittance values of less than 1.0, some infrared energy will always be reflected from a measured object’s surface. The Reflected Temperature feature found on radiometers will mathematically compensate for this error source provided that it has been properly set by the operator.
Listed below are the general steps for measuring and compensating for Reflected Temperature when using the Direct Method.
- Place imager at desired location and distance from object to be measured
- Aim and focus imager
- Estimate angle of incidence and angle of reflection
- Position imager pointing away from target & parallel to angle of reflection
- With imager focused and its E control set to 1.0, measure average apparent temperature of scene using either area measurement or isotherm feature
- Conduct procedure three times and average results
- Enter averaged value into radiometer’s Reflected Temperature input
When measuring Reflected Temperature, make certain to maintain a safe distance from any hot or energized targets and observe all necessary safety precautions. When entering Reflected Temperature into your radiometer, be sure to access the proper menu as some imagers have inputs for Reflected Temperature as well as ambient air temperature.
The above procedure is described in greater detail in the Standard for Measuring and Compensating for Reflected Temperature Using Infrared Imaging Radiometers. For more information on infrared standards or thermographer training, call 609-239-4788 or visit us online at www.infraspection.com.
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October 28, 2013
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Autumn is the Time for Steam Trap Testing
Tip written by: Infraspection InstituteWith the onset of seasonably cooler weather, autumn is the time to prepare your steam system for the upcoming heating season. Testing your steam traps before the season begins can help to pinpoint costly leaks before the heating season begins.
Traditionally, two different non-destructive technologies have been employed to test steam systems – contact ultrasonics and temperature measurement. Used individually, each of these techniques has limitations that can lead to false positive and/or false negative results. Combining temperature measurement with ultrasound can result in a highly accurate test method by following a few simple steps:
- Measure trap inlet to ensure that temperature is above 212º F. If trap inlet is below 212º F, ascertain why steam is not reaching trap
- Listen to the trap outlet with contact probe of ultrasonic unit. Continuous hissing or rushing sounds usually indicate a failed trap
- Ascertain that trap is cycling periodically. Frequent cycling may be caused by an undersized or worn trap
- Tag defective traps and document in written report
- Re-test defective traps after repair to ensure effectiveness of repair.
Always be sure to follow appropriate safety precautions especially when working with high pressure steam or when using ladders or lift equipment.
Infrared inspection of steam traps is one of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. For information on thermographer training including course locations and dates, visit us online at www.infraspection.com or call us at 609-239-4788.
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November 04, 2013
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Detecting Open Neutrals and Hot Ground ConductorsInfrared imaging is a proven technology for detecting hot spots caused by loose or deteriorated electrical connections. It is also capable of detecting hot components associated with open neutral conductors.
Basic principles state that electricity travels in a loop and needs a return path. Whether the electrical system is residential, commercial, or utility, this same principle applies. Therefore, one should see “outgoing” current flow on the main feed conductor and “return” current flow on the neutral conductor when measured with an ammeter. If the neutral conductor becomes open as a result of a failed connection or broken conductor, the return current is rerouted from the neutral pathway to a grounded object.
Common problems experienced with an open neutral are lights that burn dimmer on some circuits and others that burn brighter on other circuits. Also common are lights that flicker or turn brighter when heavy loads are applied, such as an air conditioning unit turning on.
Infrared imaging is an excellent tool for locating open neutral problems, especially for utility clients. The images below were captured during a periodic infrared scan of a overhead distribution feeder. The image shows an eyebolt anchor on a neutral line with a temperature rise of over 65 Fahrenheit (36 C) degrees. Not only did the discovery of this problem save unknown amounts of time to locate, it also prevented possible serious injury to an unsuspecting utility worker.
Having an open neutral is a dangerous situation that should be corrected as soon as possible. With an open neutral, the grounding conductor becomes energized and can cause injury to someone coming in contact with any bare metal that is intended to be at ground potential.
In most cases, open neutral problems experienced in residential and commercial buildings can be traced backed to the utility’s side of the power system. This makes sense since utility connections are far more exposed to outdoor elements that can cause breaks and failures to conductor connections.
Tip Provided by:
Brady Infrared Inspections
935 Pine Castle Court
Stuart, FL 34996Office: 772-288-9884
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November 11, 2013
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Training – A Wise Use of Year End Budget Money
Tip written by: Infraspection InstituteWhen it comes to spending year end budget monies, the phrase “Use it or Lose it” often applies. Training can be a wise choice for those looking to reduce a budget surplus.
Staying within budget is a constant challenge for maintenance managers. For many, it seems that there is never enough money in the budget. On occasion, however, it is possible to experience a surplus in one’s budget when nearing year end.
When faced with a budget surplus, it is imperative to fully utilize allocated financial resources. Failure to do so can cause a reduction in future budgeting if management perceives that your department is over funded. When searching for wise choices for year-end spending, training is always a good option.
Thermographic training is a sound investment for initiating a PdM program or expanding an existing one. Whenever considering infrared training be certain to:
- Examine course curriculum to ensure that it meets your needs
- Ensure that course will be germane to all infrared imagers
- Determine course locations or availability of Distance Learning courses
- Ascertain if certification is included with course, its expiration date, and renewal fees
- Insist that instructors be practicing thermographers with documented field experience in their area of instructionInfraspection Institute has been providing infrared training and certification for infrared thermographers since 1980. Our Level I, II, and III Certified Infrared Thermographer® training courses meet the training requirements for NDT personnel in accordance with the ASNT document, SNT-TC-1A. Certification and applications courses are offered as open enrollment or on-site classes or through our Distance Learning program. All courses are taught by expert Level III thermographers whose field experience is unsurpassed anywhere in the world. For more information call 609-239-4788 or visit us online at www.infraspection.com.Visit Infraspection Institute Web Site
November 18, 2013
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Emissivity Settings for Building Inspections
Tip written by: Infraspection InstituteA common question among thermographers who perform infrared inspections of buildings is, “What emissivity setting should I use?” While this might seem like a straightforward question, the answer is not that simple.
Recent years have seen a dramatic increase in the use of thermography as a building diagnostics tool. While many applications are qualitative, there are occasions when quantifying temperature can be useful. In order to accurately perform non-contact temperature measurements, one must input the correct emittance value into a radiometer’s computer.
While many equate emissivity to values published in emittance tables, emissivity is a dynamic characteristic that is influenced by several factors. These include: wavelength, object temperature, viewing angle, target shape, and surface condition. Each of these factors can vary between projects or during a given inspection.
Further compounding the challenge is the fact that not all imagers are created equal. Imagers lacking corrective inputs for atmospheric attenuation and/or reflected temperature often require an exaggerated emittance value be utilized.
When performing an infrared inspection of buildings, keep the following in mind:
- For qualitative inspections performed with an imaging radiometer, leave the imager’s E control set to 1.0. If possible, turn off all temperature measurement tools.
- In general, dielectric materials will have a relatively high emittance; shiny surfaces and glass will be quite reflective.
- Viewing angle and reflected temperature can greatly influence the effective emittance of a material. In particular, smooth-surface roof membranes and building sidewalls can be quite reflective when imaged at low viewing angles often associated with ground-based inspections.
Lastly, emittance values obtained from published tables can introduce significant temperature measurement errors. Whenever possible, one should calculate emittance values with the subject imager and cross verify observed temperatures with contact thermometry.
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November 25, 2013
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Thanksgiving Safety Tip
Tip written by: Infraspection InstituteWhen it comes to heat transfer and safety, thermographers traditionally think of the workplace. With the Thanksgiving holiday upon us, neither of these topics should be overlooked when it comes to preparing the holiday feast.
According to estimates from the Centers for Disease Control, approximately 76 million Americans become ill each year as a result of foodborne pathogens. Of these, approximately 5,000 die. Proper hygiene practices before, during, and after food preparation can reduce the risk of food poisoning.
As part of their nationwide Be Food Safe public education campaign, the US Department of Agriculture offers four simple tips for safe food preparation:
Clean – Wash hands, surfaces and utensils often to avoid spreading bacteria when preparing food.
Separate – Use different cutting boards for raw meat, poultry, seafood and vegetables. Keep raw turkey away from vegetables and side dishes that won’t be cooked.
Cook – You can’t tell it’s done by how it looks! Use a food thermometer. Every part of the turkey should reach a minimum internal temperature of 165ºF.
Chill – Keep the refrigerator at 40ºF or below to keep bacteria from growing. Pumpkin pie should always be refrigerated and all food should be refrigerated within two hours.If deep fried turkey is your preference, be sure to observe all safety precautions and never leave your fryer unattended. For more information on food safety, visit the US Department of Agriculture website.
From all of us at Infraspection Institute, Happy Thanksgiving to all of our readers and friends! May you enjoy a safe and happy holiday in the company of those you love.
~ Jim and Christopher Seffrin ~
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December 02, 2013
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Winter Driving Tips
Tip written by: Infraspection InstituteWith an unusually harsh winter well underway, many have already experienced driving challenges associated with severe weather. With this Tip, we offer some advice for driving in winter conditions.
Prepare Your Vehicle
- Make sure brakes, windshield wipers, defroster, heater and exhaust system are in top condition
- Check radiator for coolant level and adequate antifreeze protection. Fill windshield washer reservoir with freeze-resistant fluid
- Check tires for proper inflation and tread condition
- Carry an ice scraper, brush, and a shovel
- Maintain a full gas tank in case of traffic delays or should you need to turn back due to conditions
- Keep snow chains handy and in good condition
Driving Tips
- Allow enough time. Trips take longer during stormy/icy conditions
- Keep windshield and windows clear
- Maintain a safe distance from other vehicles; snow and ice make stopping distances much longer
- Remember to avoid sudden stops and quick direction changes
- Watch for slippery spots. Bridge decks and shady spots can be icy when other areas are not
- Be more observant. Visibility is often limited in winter by weather conditions. Slow down and watch out for stopped vehicles and emergency equipment
Lastly, be certain to wear your seat belt. Consult your local weather forecast before you set out and consider postponing your trip if extreme weather is predicted.
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December 09, 2013
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Temperature Measurement and Building Envelope Inspections
Tip written by: Infraspection InstituteTemperature measurement is recognized in many thermographic applications as a means for gauging the severity of exceptions. For infrared inspections of building envelopes, temperature measurement is frequently of little or no value and may serve to underestimate the severity of certain conditions.
Infrared inspections can be used to detect a wide variety of problems in building envelopes. These conditions include, but are not limited to: air leakage, missing or damaged insulation, latent moisture, and pest infestation. Since thermographic detection of these conditions is qualitative, temperature measurement is not required. In fact, there is no reliable means for correlating temperature with the severity of the aforementioned deficiencies. For conditions such as latent moisture, there is no acceptable temperature limit or differential.
Although temperature measurements are frequently meaningless for building envelope inspections, many thermographers routinely include them in their reports. Unfortunately, this practice can create unnecessary liability for a thermographer and damage his/her reputation if their work product is ever questioned or compared to published standards or accepted industry practice. Presently, published thermography standards and accepted industry practice do not incorporate temperature measurement into building envelope inspections.
When faced with situations where temperature measurement can be useful, thermographers should take steps to ensure the accuracy of their measurements. For non-contact temperature measurements, minimum considerations should include equipment calibration, spot measurement size, target emittance, as well as local weather and site conditions.
Infrared inspections of building envelopes is one of the many topics covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. For more information including course locations and dates, visit Infraspection Institute online at www.infraspection.com or call us at 609-239-4788.
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December 16, 2013
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Purchasing an Imager – Which Brand is Best?
Tip written by: Infraspection InstituteWhen purchasing a thermal imager, buyers frequently ask, “Which brand of imager is best?” While this seems like a straightforward question, the answer is not so simple. In this Tip we offer advice for making the correct choice.
As infrared thermography gains wider acceptance, its usage is increasing. Meanwhile, the task of selecting an imager is becoming more difficult. Presently, there is a wide selection of equipment available from a record number of manufacturers. With some manufacturers offering several variants of camera models, there are more choices than ever before.
Procuring an imager is a challenge for many reasons: initial purchase price can easily run into the tens of thousands of dollars, no imager is capable of performing all imaging applications, imager performance varies widely, performance specs are not always available or comparable, and making an incorrect purchase can be costly.
Purchasing an imager should be done by assessing your company’s present and future needs, obtaining and comparing manufacturer specifications, and taking time to thoroughly evaluate the imager in the workplace where it will be used. Prior to purchase, the imager and its manufacturer should be carefully evaluated in the following areas:
- Evaluate imagers objective and performance specifications
- Obtain service and warranty information
- Evaluate imager for subjective characteristics
- Consider equipment value
Lastly, when considering pre-owned equipment, it is often a good idea to have a title search conducted prior to purchase to ensure that the equipment is free of liens.
Equipment purchase is of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. For more information on upcoming classes or to obtain a copy of our article, Selecting, Specifying and Purchasing Thermal Imagers, call 609-239-4788 or visit us online at www.infraspection.com.
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December 23, 2013
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Holiday Wishes
Tip written by: Infraspection InstituteIt is hard to believe that another year has passed and the holiday season is once again upon us. With this Tip, we invite our readers to share a favorite memory as we celebrate the season.
Recently, we noticed a television schedule announcing the airing of one of our all-time favorite programs, ‘A Charlie Brown Christmas’. As children growing up in the 1960’s, the annual airing of this program was proof that Christmas was just around the corner.
With no reruns on broadcast television, we, like many of our childhood friends, would plan our entire week around watching this special program each year. With a cool soundtrack, the program brought our favorite Peanuts characters to life as Charlie Brown strove to discover the meaning of Christmas. To this day, Linus VanPelt’s simple monologue is one of our favorite holiday memories.
With the holidays and busy year-end schedules upon us once again, we invite you to take the time to make special memories with family and friends and to keep them in your heart where you may easily find them in the future.
As we enjoy this holiday season, we extend a heartfelt Thank You to all of our readers, friends, and associates throughout the world for everything that you do for us all year long.
May your holidays be filled with peace and joy and your New Year with good health and happiness.
~ Jim & Chris Seffrin
Linus’ Monologue
Charlie Brown: Isn’t there anyone who knows what Christmas is all about?
Linus: Sure, Charlie Brown. I can tell you what Christmas is all about. Lights, please.
And there were in the same country, shepherds, abiding in the fields, keeping watch over their flock by night and lo, the angel of the Lord came upon them. And the glory of the Lord shone ‘round about them and they were so afraid. And the angel said unto them, “Fear not. For behold, I bring you tidings of great joy which shall be to all people. For unto you is born this day in the city of David, a savior, which is Christ the Lord. And this shall be a sign unto you, ye shall find the babe wrapped in swaddling clothes lying in a manger.”
And suddenly there was with the angel, a multitude of the heavenly hosts praising God and saying, “Glory to God in the highest and on Earth, Peace and Goodwill toward men.”
That’s what Christmas is all about Charlie Brown.
Excerpted from ‘A Charlie Brown Christmas’ by Charles Schulz
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December 30, 2013
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Frostbite & Hypothermia
Tip written by: Infraspection Institute“Jack Frost nipping at your nose.” These lyrics from a popular Christmas carol evoke romantic visions of winter; however, frostbite and hypothermia are dangerous medical conditions that can present serious safety hazards.
For many, the dead of winter is upon us. Thermographers working outdoors in cold climates can face serious safety challenges due to frostbite and hypothermia. Knowing the symptoms of these conditions and proper treatment is imperative for worker safety.
Frostbite is a severe reaction to cold exposure that can permanently damage its victims. A loss of feeling and a white or pale appearance in fingers, toes, or nose and ear lobes are symptoms of frostbite.
Hypothermia is a condition brought on when the body temperature drops to less than 90 degrees Fahrenheit. Symptoms of hypothermia include uncontrollable shivering, slow speech, memory lapses, frequent stumbling, drowsiness, and exhaustion.
If frostbite or hypothermia is suspected, begin warming the person slowly and seek immediate medical assistance. Warm the person’s trunk first. Use your own body heat to help. Arms and legs should be warmed last because stimulation of the limbs can drive cold blood toward the heart and lead to heart failure. If the person is wet, put them in dry clothing and wrap their entire body in a blanket.
Never give a frostbite or hypothermia victim beverages containing caffeine or alcohol. Caffeine, a stimulant, can cause the heart to beat faster and hasten the effects the cold has on the body. Alcohol, a depressant, can slow the heart and also hasten the ill effects of cold body temperatures.
