2017
Making Your Own Blackbody Simulator
Tip written by: Infraspection Institute
Blackbody simulators are essential tools for checking the calibration of infrared imagers and radiometers. One alternative to purchasing a blackbody simulator is to make your own.
In order to provide accurate temperature values, infrared imagers and radiometers must be calibrated on a periodic basis. During the calibration process, blackbody simulators provide targets with a known temperature and a known emittance.
Thermographers wishing to perform a calibration check of their instruments may elect to purchase a blackbody simulator. Several models are commercially available with prices ranging up to several thousand dollars. As an alternative, thermographers may elect to make their own simulator from commonly available items. This may be accomplished as follows:
- Procure a 2 liter square metal can and a 60 Watt electric aquarium heater. Can opening must be large enough to allow heater to be inserted into can opening.
- Cover the exterior of the can with Scotch #191 PVC electrical tape.
- Fill the can with water to within 1” of the top and insert aquarium heater. Avoid causing can to overflow.
- Energize heater and set to desired temperature. Be certain to allow sufficient time for can temperature to stabilize.
When performing a calibration check of infrared equipment, set the subject radiometer’s emittance control to 0.97. Ascertain the can temperature using a thermocouple. Compare the two values and note any differences.
Lastly, be certain to work safely. In particular, avoid fully immersing any aquarium heater not designed for immersion. Be certain to disconnect the aquarium heater from its power source and allow it to cool prior to removing it from the can.
Equipment calibration is one of the many topics covered in the Level II 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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Roof Inspections – Solar Reflectance versus IR Reflectance
Tip written by: Infraspection Institute
Energy and environmental concerns have caused many facility owners to look to their roofing systems for ways to conserve energy. Modern roofing systems known as ‘cool roofs’ can provide savings; however, they can present challenges for thermographers who inspect them.
Over 90% of roofs in the United States are dark colored. On sunny days, temperatures of these roofs can reach 150º to 190º F causing decreased indoor comfort, increased cooling costs, and premature aging of roofing materials. Advances in roofing technology have led to the development of ‘cool roof’ systems that help to solve these challenges.
Cool roof materials have a high solar reflectance or albedo. Compared to conventional roof materials, cool roofs operate at lower temperatures since they absorb less energy from the Sun. Cool roofs also have a high thermal emittance enabling them to radiate well and shed heat quickly after sunset.
Cool roof membranes are usually made of single-ply rubber or plastic materials such as EPDM, PVC, and TPO. These materials are usually white in color and have a smooth surface. Cool roof coatings or paints are an alternative for existing low-slope roofs.
Although cool roof materials are rated to have a high emittance, thermographers should remember that this value is an average emittance value calculated in a laboratory under ideal conditions and at a perpendicular viewing angle. During an infrared inspection, smooth-surfaced roofs appear quite reflective to a thermal imager due to the low viewing angle that is usually associated with inspections performed on foot from the roof surface. This condition is most severe on cloudless nights when atmospheric humidity levels are low.
Due to the low emittance associated with smooth roof surfaces, thermographers can easily miss the small temperature differentials associated with latent moisture. In order to mitigate errors associated with low emittance, thermographers should choose a short wave (2 to 5.6 microns) thermal imager whenever inspecting a smooth-surfaced roof regardless of membrane color or material.
Infrared inspection of flat roofs and proper equipment selection are two of the many topics covered in all Infraspection Institute Level I training courses. For more information or to register for a course, visit Infraspection Institute online or call us at 609-239-4788.
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Post Processing Thermal Images
Tip written by: Infraspection Institute
Post processing of thermal images is a common practice for many thermographers. While image processing may provide a measure of convenience for some, it can have significant drawbacks.
For many thermal imagers, infrared images can be stored in 12 bit format. Saving thermal images in 12 bit format allows thermal images to be recalled at any time and post processed for level, gain and color palette. For imaging radiometers, temperature measurement settings such as emittance may also be changed. Post processing may take place within the imager or through a separate personal computer using the manufacturer’s proprietary software.
Over time, many thermographers have adopted a policy of quickly recording imagery in the field and then returning to the comfort of their office to further process their imagery. Although post processing affords the thermographer a variety of options for image analysis, one should be aware that post processing can be time consuming. Spending as little as five minutes processing imagery can result in a substantial increase in report preparation time.
In addition to wasted time, post processing may invalidate imagery as legal evidence. Not unlike digital photography, thermal images that have been post processed are creations and not originals. Should a thermographer’s report be introduced in a claim, a competent opponent will likely question if the imagery is original. In such situations, a thermographer must be able to affirm that his/her report does not contain processed imagery.
In light of the above, we recommend that thermographers store images exactly the way they will appear in their report and endeavor to avoid post processing altogether.
Image recording and reporting are two of the many topics covered in all Infraspection Institute Certified Infrared Thermographer® training courses. For information on thermographer training and certification, visit us online at www.infraspection.com or call us at 609-239-4788.
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Infrared Inspections of UPS Systems
Tip written by: Infraspection Institute
Uninterruptible Power Supply (UPS) systems are commonly found in facilities where reliable electrical power is critical. Infrared inspections can play a key role in maintaining these crucial systems.
An Uninterruptible Power Supply (UPS) system is an electrical apparatus that provides short-term emergency power to a load when the normal input power source fails. Unlike standby generators, UPS systems provide instantaneous protection from input power interruptions by means of attached batteries.
UPS systems are typically used to protect computers, data centers, telecommunication equipment or other electrical equipment where an unexpected power disruption could cause injuries, fatalities, serious business disruption, or data loss. Due to their critical role, it is imperative that UPS systems be maintained to ensure reliability when needed.
Performed under the correct conditions, thermal imaging can be useful in detecting defects within a UPS system including loose or deteriorated connections, overloads, and faulty components. When combined with regular preventive maintenance, thermal imaging can detect faults that are undetectable by other means.
When performing an infrared inspection of a UPS system, keep the following in mind:
- Panel covers should be opened or removed to afford line-of-sight access
- UPS system must be under load
- Be certain to include all current carrying devices including UPS system controls, switchgear, battery cells, battery bus, and wiring
- Inspect battery casings for discrete hot spots
- Compare batteries to each other noting any with elevated temperatures
Thermal imaging may be applied during normal operation of the UPS system or during a controlled discharge test. If imaging during the latter, a thermographer will have to work quickly to ensure complete coverage of the subject components.
Lastly, be certain to observe all necessary safety practices when working on or near energized electrical equipment.
Infrared inspection 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 or to obtain a copy of the Standard for Infrared Inspection of Electrical Systems & Rotating Equipment, visit the Infraspection website or call us at 609-239-4788.
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Pricing Infrared Inspection Services
Tip written by: Infraspection Institute
A well-known Zen riddle is, “What is the sound of one hand clapping?” A perpetual thermographer’s enigma is, “What are infrared inspection services worth?” This week’s Tip addresses some key considerations when evaluating prices for infrared inspection services.
Better, faster, cheaper – these powerful words are often used in advertising when attempting to attract new customers. Unfortunately, they fail to address the issue of quality – often one of the most important aspects of professional services such as thermography.
In determining prices for any service, one must determine all costs associated with providing services to one’s clients within a given time frame along with the amount of profit desired. The sum of these numbers, divided by the number of billable hours or days that can be sold during the same time period will yield an hourly or daily price. Depending upon how a company is structured and the desired profit margin, these numbers can vary widely.
When considering pricing for infrared inspection services, ask yourself the following questions:
- What services or features are prospects willing to pay for?
- How will the offered services add value to your client’s operation?
- What unique advantages can your company provide?
Once you have established pricing and begun to market your services, be prepared to justify your prices to prospects. Clients will often spend more for services if they can be convinced that they will receive better quality and value. Consistently having the lowest price will not win every order and can compromise a company’s longevity.
Marketing of infrared inspection services is one of the many topics covered in the Level III Infraspection Institute Certified Infrared Thermographer® training course. For more information on infrared training and certification, please call 609-239-4788 or visit us online at www.infraspection.com.
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Temperature Limits for Drive Belts
Tip written by: Infraspection Institute
Temperature is frequently used to gauge the condition of motors and power transmission equipment. In this Tip, we discuss the effect of heat on flexible drive belts and temperature limits for them.
Drive belts are an integral component on many types of machines. Despite the critical role they play in machine operation, V type drive belts tend to out-of-sight and out-of-mind until they fail. In most installations, belt temperature largely influences the life installed V belts.
As a rule of thumb, properly applied and maintained belts should not exceed 140º F (60º C), assuming an ambient temperature of less than 110º F (43º C). It should be noted that belt life can be greatly reduced by higher operating temperature. In fact, for every 18 F (10 C) increase in belt temperature, belt life is cut in half.
There are many factors that contribute to high belt operating temperature including, but not limited to: ambient air temperature, machine design, installation, alignment, and belt tension. Overheating belts can be readily detected with an infrared imager. Once detected, overheating belts should be investigated for cause and proper corrective measures undertaken as soon as possible. Doing so can help prevent unscheduled downtime and may prolong belt life.
Temperature limits for mechanical equipment is one of the many topics covered in the Infraspection Institute Level II Certified Infrared Thermographer® training course. Classes are held regularly throughout the year and are also available through our web-based Distance Learning Program. For more information, please call 609-239-4788 or visit www.infraspection.com.
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Imager Operational Check Prior to Inspections
Many infrared applications standards require that infrared test equipment be within calibration prior to the conduct of an inspection. Although performing a full calibration on a daily basis is impractical, performing some simple operational checks can help to ensure that equipment is functioning properly.
Prior to commencing an infrared inspection, a thermographer should set up his/her equipment by:
- Checking imager optics for cleanliness
- Ensuring that batteries are fully charged
- Inspecting power and video cables/connectors for electrical integrity
- Allowing imager to stabilize with ambient temperature
After completing the above, power-up the thermal imager and note that the imager initializes properly. Once the imager has initialized, adjust imager controls to normal temperature range. Focusing on a high emittance target such as a tabletop or a wall covered with latex paint, check the monitor for image clarity. If the image has inexplicably hot or cold pixels, perform a non-uniformity correction.
Once the image appears clear, a small Delta T can be created by placing one’s hand on one of the above high E surfaces for a few seconds. After removing the hand, image this same area and note the thermal pattern and its intensity. With a properly operating thermal imager, the thermal pattern of the hand should be clearly visible and last for at least one minute.
For more information on thermographer training and certification, contact Infraspection Institute at 609-239-4788 or visit us online at www.infraspection.com.
Blinded by the Light
While it is often interesting to use a thermal imager to view ordinary objects, imaging the sun, arc welders and similarly hot objects should be avoided unless your imager has been built specifically for these applications. The reason for this is that the sensitive thermal detector that comprises the heart of any thermal imaging system can be destroyed by imaging very hot objects, even for brief periods of time.
To help avoid a costly detector replacement, only image objects whose temperatures are within the stated operating range of your imager.
Perhaps a sage corollary could be derived from Bruce Springsteen’s epic song, Blinded by the Light:
… Mama always told not to image into the sights of the Sun…
A ruined detector assembly is NOT where the fun is.
Equipment selection and use are two of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. For information on thermographer training including our Distance Learning program, visit us online at www.infraspection.com or call us at 609-239-4788.
School’s Open – Drive Carefully
Tip Provided by American Automobile Association
By early September, over 55 million children across the United States will head back to school. With 13 percent of those children typically walking or biking to their classes, drivers should be especially vigilant for pedestrians before and after school hours. The afternoon hours are particularly dangerous – over the last decade, nearly one in four child pedestrian fatalities occurred between 3 p.m. and 7 p.m.
Launched in 1946, the American Automobile Association’s School’s Open – Drive Carefully awareness campaign was created as a way to help reduce child pedestrian fatalities and injuries. Here are several recommendations from AAA regarding ways drivers can help to keep kids safe:
- Slow down – Speed limits in school zones are reduced for a reason. A pedestrian struck by a vehicle traveling at 25 mph is nearly two-thirds less likely to be killed compared to a pedestrian struck by a vehicle traveling just 10 mph faster.
- Come to a complete stop – Research shows that more than one-third of drivers roll through stop signs in school zones or neighborhoods. Always come to a complete stop, checking carefully for children on sidewalks and in crosswalks before proceeding.
- Eliminate distractions – Research shows that taking your eyes off the road for just two seconds doubles your chances of crashing. Children can be quick, crossing the road unexpectedly or emerging suddenly between two parked cars. Reduce risk by not using your cell phone or eating while driving.
- Watch for bicycles – Children on bikes are often inexperienced, unsteady, and unpredictable. Slow down and allow at least three feet of passing distance between your vehicle and a bicyclist.
Lastly, always maintain a safe distance from a stopped school bus. Be on the lookout for children boarding or exiting school buses.
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September 04, 2017
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Infrared Inspections of Lightning Arrestors
Tip written by: Infraspection Institute
Infrared thermography is a proven technology for detecting defects in electrical circuits that are under load. Thermal imaging can also be used to detect defective lightning arrestors that are leaking current to ground.
Lightning arrestors are a common feature in electrical distribution systems and are used to guard against voltage surges associated with lightning strikes on power or communications lines. Installed at strategic locations, lightning arrestors act like safety valves to provide a short circuit path that carries excess voltage to ground during a lightning strike.
Lightning arrestors are connected between a conductor and ground. In order to prevent a ground fault, lightning arrestors are engineered so that normal line voltage will not pass through the arrestor under normal conditions. While some lightning arrestors employ a simple spark gap, others consist of porcelain tubes that are filled with semi-conductive discs made of silicon carbide or zinc oxide. During a lightning strike, the resistance of the spark gap or oxide plates is overcome and excess energy flows to ground.
If a lightning strike is sufficiently strong, lightning arrestors may be permanently damaged and begin to conduct electricity to ground full time. When this happens, the body of the arrestors will heat up allowing them to be detected with a thermal imager. The images below show two examples of defective arrestors.
~ Images courtesy Stockton Infrared Thermographic Services
Infrared inspections of lightning arrestors are primarily qualitative in nature. As such, thermographers should compare similar arrestors to one another and note any that are inexplicably warm.
Properly functioning lightning arrestors should be uniform in temperature and close to ambient air temperature if they have not undergone recent solar loading. Individual arrestors should not have any pronounced hot spots across them. Working early in the morning, on cloudy days or at night will help to eliminate solar loading which can hide defective arrestors. When performing your inspection, don’t forget to check grounding connections for hot spots as well.
Infrared inspection 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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September 11, 2017
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Point Radiometers & Spot Measurement Size
Tip written by: Infraspection Institute
With 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.
September 18, 2017
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Change Routes with the Season
Tip written by: Infraspection Institute
To everything there is a season. The same is true for infrared inspection routes within facilities where equipment or systems are operated seasonally.
Traditionally, many facilities perform infrared inspections on an annual basis. While this approach may detect deficiencies within operating systems, systems not under load due to seasonal or operational conditions cannot be effectively inspected.
Examples of seasonally operated equipment include heating/cooling systems, production machinery, and the electrical distribution system. Effective infrared inspections of seasonally operated equipment begin at the planning stages and should include the following:
- Develop an inventory list of equipment to be inspected
- Group seasonally operated equipment into dedicated routes
- Ascertain operating times for subject systems
- Schedule infrared inspections for the beginning of operating season
- Inspect subject systems while under normal load
Be certain to perform a follow up inspection for all detected exceptions once necessary repairs have been completed. As always, remember to observe all necessary safety precautions before, and during the infrared inspection.
The topic of route based infrared inspections and how to properly organize inspection routes 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 25, 2017
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The Myth Behind IFOV Values
Tip written by: Infraspection Institute
A specification commonly provided for thermal imagers is Instantaneous Field of View or IFOV. Many people mistakenly believe that IFOV values provide meaningful information about a thermal imager’s performance. Unfortunately, this is simply not true.
Originally developed for evaluating the optical performance of thermal imaging systems, IFOV values were intended to allow a user to calculate the minimum target size needed to achieve 50% probability of detection at any given distance. Using IFOV values to evaluate modern thermal imagers and radiometers is unreliable for several reasons:
- To date, there is no accepted standard for determining IFOV. Consequently, imager manufacturers calculate IFOV values differently, making test results impossible to compare.
- Because IFOV values are reported for a single pixel, they cannot be used to accurately calculate spot measurement size for imaging radiometers since accurate temperature measurement requires several pixels, not just one.
- Stated IFOV values are traditionally reported at 50% radiance or less which is unreliable for both temperature measurement and accurate thermal imaging.
The Infraspection Institute Standard for Measuring Distance/Target Size Values for Infrared Imaging Radiometers provides a simple and effective method for determining spot measurement size for any quantitative infrared imager. Proper use of this standard is taught in all Infraspection Institute Level II training courses.
For more information on thermographer training and certification or to obtain a copy of the standard, visit us online at www.infraspection.com or call us at 609-239-4788.
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October 02, 2017
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Calculating the Value of an Electrical Hotspot
Tip written by: Infraspection Institute
What is the financial liability of a hotspot within an electrical system? Probably less than you think since electrical hotspots waste surprisingly little energy even when operating at high temperatures.
Over time, many have stated that the cost of infrared inspections can be justified through the detection and subsequent repair of hotspots associated with loose/deteriorated electrical connections. Although these types of defects can produce temperature rises of hundreds of degrees, the amount of energy wasted in the form of excess heat is often surprisingly small.
When detected in their formative stages, loose/deteriorated connections may contribute to only a few watts of energy loss. Even large temperature rises associated with significantly degraded connections will usually produce energy losses of less than 100 watts. We can calculate the financial impact of such an exception as follows:
0.1 kw x 24 hours = 2.4 kwh per day
876 kwh per year x $0.14 per kwh = $122.64 per year
It is important to note the above illustration is for an extreme hotspot operating undetected 24 hours per day for an entire year. While the above potential savings may seem significant, it would be hard to justify the expense of an infrared inspection program based upon energy savings alone. Justification would be even harder if the dissipated energy were only a few watts.
The real value of information obtained from infrared inspections comes from reducing unscheduled downtime, increasing reliability, improving safety, and avoiding losses associated with catastrophic failure.
Infrared inspection 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 or to obtain a copy of the Standard for Infrared Inspection of Electrical Systems & Rotating Equipment, visit us online at www.infraspection.com or call us at 609-239-4788.
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October 09, 2017
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Using a Blower Door During an IR Inspection
Tip written by: Infraspection Institute
Data obtained during infrared inspections can often be improved by incorporating other tools. When it comes to building inspections, a blower door can be useful in detecting air leakage sites and helping to gauge the airtightness of a building.
Air leakage is often a major source of energy loss in buildings. Although an infrared imager can help detect evidence of air leakage sites, it cannot pinpoint all air leakage sites nor can it quantify the amount of air leakage occurring. Many thermographers overcome these limitations by utilizing a blower door in conjunction with their infrared inspection.
A blower door consists of an instrumented, high volume fan that is temporarily placed in a doorway to create a positive or negative pressure within a building. In depressurized mode, the blower door simulates a wind blowing equally on all sides of the building. Conducting an infrared inspection with the building depressurized enables a thermographer to detect air leakage sites that would not be visible under natural conditions. With special software, it is possible to estimate the relative leakage of a structure as well as the total area of all leak sites.
A blower door can provide a thermographer with some advantages; however, there are challenges associated with their use. Using a blower door during an infrared inspection represents a “worst case” scenario and may not be indicative of natural conditions. This may invalidate thermal imagery that is destined for use in a legal case. Since blower doors can cause backdrafts from fireplaces, stoves, and heating equipment, they should be operated only by persons who are properly trained in their application and use.
Infrared inspection of building envelopes 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.
October 16, 2017
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IR Imaging for Checking Tank Levels
Tip written by: Infraspection Institute
For 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.
outdoor storage vessel. Image courtesy of www.imaging1.com
In 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.
October 23, 2017
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An Emittance Greater Than 1.0 ?
Tip written by: Infraspection Institute
According to the laws of physics, only a perfect blackbody may have Emittance of 1.0. Although the E value of real objects must be less than 1.0, some radiometers allow entry of E values exceeding 1.0. The following describes how these radiometers achieve the impossible.
Emittance is a measure of how well an object radiates energy when compared to a blackbody at the same wavelength and temperature. Emittance for any object is measured on a scale between 0 and 1.0. Since blackbodies (E=1.0) exist only in theory, real world objects will have E values of less than 1.0. The E value of an object can never exceed 1.0.
Assuming that most objects are opaque (T=0), they must be somewhat reflective. When making an infrared temperature measurement, this reflected energy represents an error source. To overcome errors due to reflections, quality radiometers have inputs for reflected temperature. By measuring reflected temperature and entering this value into the radiometer’s computer, this error source is compensated for in the radiometer’s software.
Less sophisticated radiometers often lack inputs for reflected temperature. To compensate for this, these radiometers allow the user to exceed E values of 1.0. Although this overcompensation may allow the user to match a desired reference temperature, it can lead to significant errors. For infrared temperature measurement, the best solution is to use quality radiometric equipment and eliminate or avoid reflections whenever possible.
Emittance and proper imager operation are two of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. For information on our open enrollment or Distance Learning courses, please visit us online at www.infraspection.com or call us at 609-239-4788
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October 30, 2017
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Easier Than A, B, C
Tip written by: Infraspection Institute
When performing infrared inspections of electrical distribution systems, many people identify the individual phases of polyphase circuits as A, B, and C; others frequently use 1, 2, and 3.
Confusion can arise with alphabetical or numerical labels particularly when switchgear enclosures are inspected from different perspectives e.g. front versus rear. Further confusion can occur when phase rotation has been modified or changed or, in some cases, mislabelled.
Reference errors can be avoided by using terms that cannot be confused such as Left, Middle, Right OR Upper, Middle, Lower. When using such terms, one should always reference where the image was taken from. For outside power lines references such as Street, Center, and Field may be used to identify phases without confusion.
Using the above simple terms can make your reports easier to understand and help to eliminate confusion when repairs are performed.
Infrared inspection of electrical distribution systems is one of the many applications covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. For course schedules or to obtain a copy of the Standard for Infrared Inspection of Electrical Systems and Rotating Equipment, visit Infraspection Institute online at www.infraspection.com or call us at 609-239-4788.
November 06, 2017
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Does Thermography Really Save Time and Money?
Tip written by: Infraspection Institute
“Thermography saves time and money” is a statement frequently associated with thermal imaging. In this Tip, we discuss the accuracy of this popular claim.
Whether you work as a professional thermographer or are setting up an in-house infrared inspection program, it is important to accurately represent the benefits of thermography to prospects or peers. Failure to do so can lead to unrealistic expectations and disappointment.
The statement, ‘Thermography saves time and money’ is a popular phrase associated with our technology; however, it is a fallacy. As a practice, thermography alone saves neither time nor money. This is due to the fact that infrared inspections require time for their planning and execution, both of which come with a cost. Furthermore, correcting detected exceptions will require additional time and money.
When describing the benefits of thermography, it is important to accurately represent its capabilities in order that others may set their expectations appropriately. This is especially important when seeking approval for in-house programs in order that they may be appropriately funded and staffed.
To this end, a better alternative to the aforementioned statement might be:
Combined with timely, effective repairs, thermography can help to save time and money by avoiding unscheduled downtime or premature failures.
The application of thermal imaging is a topic covered in all Level I Infraspection Institute Certified Infrared Thermographer® training courses. For more information on course locations and dates or to learn more about our Distance Learning courses, visit infraspection.com or call us at 609-239-4788.
November 13, 2017
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Checking IR Equipment Calibration
Tip written by: Infraspection Institute
Equipment calibration can have a significant impact on the accuracy of infrared temperature measurement. In this Tip we discuss a simple technique for checking the accuracy of imaging and non-imaging radiometers.
Infrared radiometers must be within calibration in order to accurately measure temperatures. Traditionally, thermographers periodically send their equipment to the manufacturer for calibration. For some, this process can take several weeks and can be rather expensive. As an alternative, savvy thermographers can check the calibration of their instrument quickly and easily using some commonly available items.
In order to check infrared radiometer calibration, you will need at least two targets each with a known temperature and emittance. A simple solution is to use a container of ice water and a container of boiling water with a coupon of Scotch PVC electrical tape affixed to the container’s exterior surface. The size of both targets must exceed the spot measurement size of the instrument being calibrated. Container temperatures may be ascertained with a thermometer, thermocouple or contact radiometer.
Once targets have been prepared, use the following procedure:
- Turn radiometer on and allow it to stabilize to room temperature
- Set radiometer perpendicular to target surface
- If possible, set radiometer inputs for distance, humidity & air temperature
- Aim, focus and calculate Reflected Temperature
- Set radiometer emittance control. Scotch 191 tape = 0.97 LW or SW. Ice = 0.98 LW; 0.93 SW
- Using subject radiometer, measure temperature of target. For ice water, measure temperature of ice cubes. For hot water container, measure tape coupon.
- Compare radiometer’s value with contact temperature reading for each target to ensure that radiometer is within spec
A heated blackbody simulator can be used to check instrument calibration at higher temperatures. Because radiometer calibration is not user-adjustable, it will be necessary to return it to the manufacturer should you find your instrument is out of spec.
Verifying infrared equipment calibration is specifically covered within Infraspection Institute’s online short course, How to Check Infrared Equipment Calibration. Available 24 hours per day, this 27 minute course focuses on the simple, yet effective techniques for calibrating infrared equipment. The techniques demonstrated are compliant with accepted industry practice and ISO standards. For more information or to register, please visit: https://www.infraspection.com/product/successiries-108/.
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November 20, 2017
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Thanksgiving Safety Tip
Tip written by: Infraspection Institute
When 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.
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November 27, 2017
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Infrared Inspections to Detect Latent Moisture
As interest in building remediation has increased, thermography has become a common tool for helping to detect moisture damage. Knowing when and how to conduct an infrared inspection is key to success.
Water infiltration into buildings can have devastating effects on building materials. Left untreated, latent moisture can cause excess energy loss, mold growth and/or structural failure. Latent moisture also causes changes in the thermal capacitance and conductivity of materials.
Prior to performing an infrared inspection, determine the best vantage point for imaging. Insulated roofs and exterior building finishes such as EIFS are traditionally inspected from the exterior of the building. Interior inspections are usually effective when moisture is affecting interior finishes of the building such as drywall. Thermal imaging may not be effective for low emittance targets.
Next, choose an appropriate time to ensure that a detectable Delta T will be present. For roofs and building exteriors, best results are usually obtained during evening hours following a sunny day. As an alternative, inspections may also be performed when there is an inside/outside temperature differential of at least 10Cº. In some cases, inspections performed from the interior may be performed with a smaller Delta T.
Thermal signatures associated with latent moisture will vary with type of building material and the amount of moisture contained therein. Depending upon vantage point and time of inspection, exceptions caused by latent moisture may show as either hot or cold thermal anomalies. These anomalies may be amorphously shaped, mottled, or correspond to the size and shape of absorbent materials. All thermal data should be correlated with invasive testing to ascertain moisture content of inspected areas.
Infrared inspection of buildings 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.
December 04, 2017
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IR Inspections of Emergency Power Systems
Tip written by: Infraspection Institute
UPS systems and emergency generators are common defenses for facilities where uninterrupted electrical power is critical. Performed properly, IR inspections can help to improve reliability of emergency power systems.
Most facilities perform IR inspections of their electrical distribution systems at least annually as part of a PM program. To help ensure maximum reliability, regularly-scheduled IR inspections should also include the emergency power systems as well. When performing infrared inspections of emergency systems be sure to:
- Inspect all backup generators while running. Begin inspection at generator output leads and proceed to generator bus, breakers, and switchgear.
- Include all Automatic and Manual Transfer Switches. Inspect switches in both normal and emergency positions.
- Inspect UPS system controls, switchgear, battery cells, battery bus and wiring. Battery cell temperatures should be the same between cells with no hotspots on individual cells.
- Have adequate load on the subject emergency circuits. This may be accomplished with normal facility load or by utilizing a load bank.
Taking the time to properly include your emergency power equipment in your IR inspection program can pay huge dividends by increasing the likelihood that your backup equipment won’t leave you in the dark should the power fail.
Infrared inspection of emergency power equipment is one of the many applications covered in the Infraspection Institute Level I training courses. For course schedules or to obtain a copy of the Standard for Infrared Inspection of Electrical Systems and Rotating Equipment, visit Infraspection Institute online at www.infraspection.com or call us at 609-239-4788.
December 11, 2017
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Winter Driving Tips
Tip written by: Infraspection Institute
With 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 18, 2017
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Temperature Measurement and Building Envelope Inspections
Tip written by: Infraspection Institute
Temperature 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, or to obtain a copy of the Standard for Infrared Inspection of Building Envelopes, visit Infraspection Institute online at www.infraspection.com or call us at 609-239-4788.
December 25, 2017
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Detecting Electrical System Overloads
Tip written by: Infraspection Institute
Statistically, overloaded circuits are the second most common cause of exceptions found during infrared inspections of electrical systems. Although overloads are quite common, they can be tricky to accurately diagnose.
As electrical current flows through a conductor, heat is generated. As circuit load increases, so does the amount of heat. Electrical circuits are designed so that loads will not exceed the circuit’s ability to safely carry a sustained load and the amount of heat associated with such load.
Typically, overcurrent protection devices such as fuses or circuit breakers are designed to protect circuits from overload conditions. These devices will interrupt the circuit when the current reaches a predetermined level for a specified period of time.
Serious problems such as fires can be caused by sustained overloads. Such overloads may be caused by: improperly sized wiring, and improperly sized or defective overcurrent protection. Fortunately, a thermal imager can be used to detect the thermal patterns associated with sustained overloads.
When using a thermal imager to detect potential overloads, one should keep the following in mind:
- Overloaded conductor(s) will be uniformly warm throughout entire length
- For polyphase circuits, all conductors may be uniformly warm
- Depending upon ambient conditions and imager settings, overloaded circuits may not appear remarkably warmer than adjacent circuits
Because an infrared imager cannot measure electrical current, suspected overloads must be confirmed with an ammeter while observing all requisite safety precautions. For greatest accuracy, a true RMS sensing ammeter is recommended. Circuits found to be overloaded should be immediately investigated for cause and corrected.
Infrared inspection 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 or to obtain a copy of the Standard for Infrared Inspection of Electrical Systems & Rotating Equipment, visit us online at www.infraspection.com or call us at 609-239-4788.
