IR Inspections of Parking Garage Ceilings
Tip Coauthored by Wayne Swirnow Infrared Imaging Services
When inspecting building envelopes for heat loss, thermographers tend to focus their imaging efforts on the sidewalls and roof. For some buildings, it is important to also thermographically inspect the underside of the building.
In many parts of the United States a common building practice for commercial structures is to elevate the building on support columns and place an unheated parking garage directly below the first story. This practice exposes the underside of the first occupied level and its associated plumbing to the outside environment.
In colder regions a common approach is to construct a suspended ceiling for the garage and to create a heated space between the underside of the first occupied floor and the garage ceiling so that water, waste, and sprinkler pipes do not freeze. To minimize heat loss, batts of glass fiber insulation are often laid directly on top of the ceiling tiles.
When performed under proper conditions, an infrared inspection of the garage ceiling can quickly reveal thermal patterns caused by missing, misapplied, or damaged insulation. Areas exhibiting excess energy loss may then be visually inspected to ascertain cause.
Infrared inspection of building envelopes is one of the many topics covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. For course information or to obtain a copy of the Standard for Infrared Inspection of Building Envelopes, visit Infraspection Institute online or call us at 609-239-4788.
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IR Inspection of Liquid-filled Transformers
Tip written by: Infraspection Institute
A thorough infrared inspection of an electrical transformer can point out symptoms of loose connections as well as other possible problems. When performing an infrared inspection of a liquid-filled transformer, be certain to include not only the primary and secondary connections but also the following items as well:
- Inspect neutral and grounding connections for hot spots
- For transformers with separate tanks for each phase, compare phase tanks to each other. Transformers with balanced loads should exhibit similar temperatures between tanks.
- Qualitatively inspect radiator sections. Radiator tubes should be uniform in temperature and, in most cases, should operate above ambient temperature.
- Compare transformer operating temperature to nameplate rating. For long term service, transformers should not operate above their maximum rated temperature.
- Compare tap changer tank to main body of transformer. For properly operating tap changers, tap changer tank should not appear warmer than main body of transformer.
In conjunction with the infrared inspection, cooling fans and/or pumps should be checked for proper settings and operation. Finally, transformers require proper air circulation for cooling. To help ensure maximum airflow, transformer radiators should be unobstructed and free from dirt and debris.
Infrared inspections of electrical 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, Skype 609-239-4788.
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January 16, 2023
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Accuracy and Sensitivity – Part 1
Tip provided by Wayne Swirnow – Infrared Imaging Services, LLC
Objective specifications are frequently used to describe the performance of thermal imaging systems. In this two-part Tip, we explore the significance of two commonly used, but frequently misunderstood terms: Accuracy and Sensitivity.
Infrared cameras along with most other electronic measurement systems have to manage their own sources of measurement error. These error sources include detector electronics, signal-to-noise ratios along the signal path, non-linearity, thermal drifting of components, gain/offset adjustments, and a host of other internal electronic workings in the measurement chain of the camera. Each component adds its contribution to the overall error of the camera as a measurement system.
Because many electronic measurement systems are similar in function, that is to detect and convert real world analog information into digital numbers, they all tend to use the same two specifications called “Sensitivity” and “Accuracy”. These two specifications combined describe the unit’s ability to state how close the converted value will be to the actual value of the input.
The Sensitivity specification for an infrared imager states the smallest amount of detectable change in the level of radiant power the camera can sense and convert into a digital number. Any change in radiant power smaller than this amount will not be recognized by the system. It is usually a very small number, (near LSB level in digital terms) and for infrared cameras it’s commonly stated as a fraction of one degree C. Typical specifications for Sensitivity are in the range of 0.2°C , 0.1°C or 0.06°C at a given temperature such as 30°C.
Because Sensitivity values are calculated using a blackbody simulator under laboratory conditions, they represent a best case scenario. An imager’s sensitivity can be significantly affected when imaging real world targets. Factors which influence sensitivity include, but are not limited to: target temperature, target emittance, and imager measurement range.
In part 2 of this Tip we will discuss the topic of Accuracy.
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January 23, 2023
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Accuracy and Sensitivity – Part 2
Tip provided by Wayne Swirnow – Infrared Imaging Services, LLC
Objective specifications are frequently used to describe the performance of thermal imaging systems. In part two of this Tip, we explore the significance of our second frequently misunderstood term, Accuracy.
For an infrared camera, the Accuracy specification states how close the camera’s measurement of radiant power will be to the actual radiant power emitted from a target. Things would be less confusing if this spec was called “Inaccuracy” or “Allowable Error” because it is really stating how inaccurate the camera is allowed to be.
Taking a closer look at the specification for Accuracy, it is made up of two separate components which are combined to give a complete statement of Accuracy:
The “Minimum” part of the spec is expressed as a window of temperature where what is measured is guaranteed to be no further away from the actual input than this spec. A typical specification is “± 2ºC”. This part of the spec covers the camera’s error or inaccuracy when dealing with lower levels of radiant power or lower temperature targets.
The “Maximum” part of the spec is expressed as a percentage of the measured value where what is measured is guaranteed to be no further away from the actual input than this spec. A typical specification is “± 2% of reading”. This part of the spec covers the camera’s error or inaccuracy when dealing with higher levels of radiant power or higher temperature targets.
As the measured value gets larger, the relative contribution from error remains the same as a percent of the total measured value, but its absolute value goes up. For example, 2% of 100 is “2”, but the same 2% of 1000 is “20”. As the measured temperature value increases to say 500ºC, then the ±2ºC spec is inadequate to express the camera’s accuracy because 2ºC out of 500ºC would be less than .05% error and that is not what the camera can do.
This is why the percentage of reading (± 2% of reading) component of the spec is needed and why for larger measurement values it now becomes the dominant factor in the Accuracy spec. And just to make sure the entire range of accuracy in the camera is covered regardless of the measurement value, manufacturers add the statement, “whichever is greater”.
Now that we understand the separate components of an Accuracy specification, here is the total statement of how well you can expect a typical infrared camera to measure the radiant power of an object:
“Accuracy = ± 2ºC or ± 2% of reading, whichever is greater”
If this is unclear, try this:
Imagine a marksman shooting at a target and we want to describe his ability to hit the bull’s eye mark every time, or more appropriately, define how far away from the bull’s eye he is allowed to deviate. Let’s also define how tightly his shots will be grouped. But here is the problem: hitting the bull’s eye and making tight groups are two separate talents our marksman possesses. Although they are related, they do operate independently in this shooter and therefore need to be discussed and defined individually.
For our marksman, we’ll assign some infrared camera specifications to his shooting so we can set expectations as to his anticipated performance.
Sensitivity – ability to group shots together
Specification: 0.1 inch
Expectation – Our marksman can place shots within one tenth of an inch of each other
Accuracy – ability to hit the bull’s eye dead center
Specification: ± 2 inches or ± 2% of the distance from the target whichever is greater
Expectation – Our marksman is allowed to miss the bull’s eye by up to 2 inches; greater inaccuracy is allowed as distance to the target increases.
As you can see in this example, his grouping talents do not help him in hitting the bull’s eye. By specification he is allowed to miss the bull’s eye by up to 2 inches. Regardless of a camera’s fantastic “Sensitivity” spec, it is allowed to miss an accurate temperature measurement by its “Accuracy” spec!
Tip provided by Wayne Swirnow – Infrared Imaging Services, LLC
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January 30, 2023
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Gauging Solar Loading
Tip written by: Infraspection Institute
Did you know that an automobile can be used to gauge solar loading? Under the correct conditions, a parked car can serve as a cheap, but effective, pyranometer.
Many types of infrared inspections rely on solar loading to heat the target so that infrared imaging may be performed successfully. Applications include, but are not limited to, low slope roof inspections, concrete bridge decks, storage vessel levels and latent moisture within building sidewalls. Ensuring that enough solar loading has occurred is imperative to collecting good data.
Good solar loading conditions are easy to recognize – long days with bright sunny skies, low humidity and no wind. More tricky is being able to determine if less than optimal conditions are allowing for appreciable solar gain.
A time tested method for gauging solar loading is to check the interior of a parked automobile. With the engine stopped and the windows and doors closed, allow the vehicle to sit in the sun for up to an hour. Immediately upon opening the door, check to see if the vehicle interior has exceeded outdoor ambient temperature. If a noticeable difference is not detected, feel the dashboard to see if it has warmed. If not, it is likely that appreciable solar loading has not occurred and it may be best to reschedule your solar driven inspection for another day.
Active thermography, including how use the Sun to create desired temperature differentials, is one of the many topics covered in all Infraspection Institute Level I training courses. For more information on thermographer training including our Distance Learning Courses, visit Infraspection Institute online or call us at 609-239-4788.
February 6, 2023
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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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February 13, 2023
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What Do Thermometers Measure?
Tip written by: Infraspection Institute
When asked what a thermometer measures, most people will tell you that thermometers measure whatever they contact. The correct answer is a little more complex and is fundamental to understanding and accurately applying contact thermometry.
Contact thermometry is a common technique used in temperature measurement. Thermocouples, resistance temperature devices, thermistors, and bulb thermometers are used to gauge the temperature of a wide variety of objects, materials, and systems. Although each works on a different principle, all contact temperature devices have one thing in common: contact thermometers report their own temperature.
Because contact thermometry is often used by thermographers to confirm radiometric measurements and to calibrate infrared equipment, accuracy is extremely important. To help ensure accuracy when using a contact thermometer, keep the following in mind:
- Select thermometer appropriate for task. Be sure to consider sensor size, thermometer sensitivity, operating range, and response time
- Prior to use, confirm that chosen thermometer is calibrated and operating properly
- Make certain that selected thermometer is in good contact with object
- Allow sufficient time for thermometer to achieve thermal equilibrium with object
Prior to using a contact thermometer, make certain that the surface to be measured is safe to touch. Never use a contact thermometer on energized electrical equipment or on any machinery where contact could result in personal injury.
Advanced heat transfer and temperature measurement are some of the many topics covered in the Infraspection Institute Level II Certified Infrared Thermographer® training course. For course schedules or to register for a course, visit Infraspection Institute online or call us at 609-239-4788.
February 20, 2023
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Infrared Inspections of Arc Fault Circuit Interrupters
Tip written by: Infraspection Institute
Excess heating is often a sure sign of defective electrical equipment; however, the absence of heat can also be a sign of component failure. In this Tip, we demonstrate how thermal imaging may be used to detect defective Arc Fault Circuit Interrupters.
An Arc Fault Circuit Interrupter (AFCI) is an advanced type of electrical circuit breaker that automatically opens a circuit when it detects a dangerous electrical arc on the circuit it protects. Designed to help prevent electrical fires, an AFCI can sense between electrical arcs caused by defective equipment versus those associated with the normal operation of devices such as light switches.
In order to monitor for dangerous electrical arcing on a circuit, AFCI devices have electronic circuitry built into them. This circuitry can cause the body of the AFCI to run several degrees warmer than ambient temperature. Depending upon the settings of your thermal imager, these devices may show a marked contrast to their surroundings.
When thermographically inspecting AFCI devices, be sure to inspect the line and load side connections at the AFCI device as well as the neutral bus bar connection for the subject breaker. Should you find an AFCI device that is operating close to ambient temperature, it is likely that the internal circuitry has failed making the device incapable of protecting against arc faults. Such devices should be further tested and replaced if they are found to be defective.
Infrared inspection of electrical 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.
February 27, 2023
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A Thermographer’s Magic Marker
Tip suggested by: Randall D. Cain, American Water Company
An age-old challenge for thermographers is the ability to annotate or mark objects to make them easier to identify in recorded imagery. One possible solution is to mark targets with an ink pen with low emittance ink.
Many thermographers have long sought ways to mark targets in such a fashion that numbers or text can clearly be seen with a thermal imager. Over time, some thermographers have used paints with emittances that contrast sharply with the objects being marked. In these cases, text and/or numbers painted on the target are clearly visible within resulting thermal imagery and recorded thermograms.
Recently some thermographers have reported good results in utilizing a Sharpie permanent felt-tip marker in silver color. The low emittance of the metallic ink contrasts markedly with high emittance targets allowing annotations to clearly appear within thermal images. In many cases, the silver ink can also be clearly seen in daylight images as well. An example can be seen below.
One should be aware that Sharpie markers are permanent unless the ink is applied to a removable material such as tape or labels affixed to the target. Prior to marking any target, be certain it is safe to do so and that marking will not permanently damage the target.
For more information on thermographer training and certification or to obtain a copy of the Standard for Infrared Inspection of Electrical Systems and Rotating Equipment, call Infraspection Institute at 609-239-4788 or visit us online at wwww.infraspection.com.
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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 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 on class locations or our Distance Learning program, visit www.infraspection.com or call 609-239-4788.
Combining IR & Ultrasound for Steam Trap Testing
In order to increase the accuracy of thermographic inspections of steam traps, contact ultrasonic testing should be used as well as infrared imaging. Contact ultrasonics are much more sensitive to trap failures than temperature measurement alone.
Over time, 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 a written report
- Re-test defective traps after repair to ensure the effectiveness of repairs
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.
Renting a Thermal Imager
Whether you are facing an equipment shortage or looking to evaluate the characteristics of a new imager prior to purchase, renting a thermal imager may provide a solution. As with purchasing an imager, there are several important things to consider when arranging for a rental unit.
To help ensure that you select an appropriate imager for rental, be certain to:
- Identify appropriate spectral response required for project
- Determine if temperature measurement is required
- Evaluate the system for objective specifications
- Ascertain imager compatibility with reporting software
When arranging for a rental, obtain terms and conditions from the rental agency. These should include, but not be limited to: rental period, extension of rental, shipping costs, and requirements for insurance against loss. One should also consider the rental agency’s ability to provide technical support during the rental period.
For more information on specifying an infrared imager, refer to the article, “Selecting, Specifying, and Purchasing a Thermal Imager” which may be found on this website here.
Lastly, the greatest limiting factor in any infrared inspection is the thermographer. To help ensure accurate results, infrared inspections should only be performed by properly trained and experienced thermographers. For more information on thermographer training, call 609-239-4788 or visit Infraspection Institute online.
Spring is the Time for Infrared Roof Inspections
Tip written by: Infraspection Institute
With the onset of warmer weather, the harshness of winter is but a fading memory for most. Left undetected, the damage caused by winter’s fury is a reality that can lead to premature roof failure. Fortunately, an infrared inspection of your roof can detect evidence of problems before they get out of hand.
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.
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 obtain a copy of the Standard for Infrared Inspection of Insulated Roofs, visit Infraspection Institute 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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How to Use Spot Size Ratios
Tip written by: Infraspection Institute
With awareness of infrared technology at an all time high, point radiometers have become a common tool in a wide variety of industries. Understanding how to properly apply spot size values is imperative for accurate temperature measurement.
For non-contact radiometers, manufacturers typically supply spot size values. These values are usually expressed as a ratio such as 50:1. Spot size ratios allow one to calculate the minimum target size for a given distance or the maximum distance for a given target size. The formulae for these calculations are as follows:
Distance to Target ÷ Spot Ratio = Minimum Target Size
Example: Using a radiometer with a spot ratio of 50:1, calculate minimum target size at 25″ from a target
Solution: 25″ ÷ 50 = 0.5″
Target Size x Spot Ratio = Maximum Distance
Example: Using a radiometer with a spot ratio of 50:1, calculate maximum distance for measuring a 1″ target
Solution: 1″ x 50 = 50″
It should be noted that non-contact radiometers are subject to minimum focus distances. Prior to using the above formulae, ascertain the minimum focus distance for your radiometer. The formulae contained herein are only applicable at or beyond a radiometer’s minimum focus distance.
Lastly, spot size ratios supplied by manufacturers are frequently quoted at 90% radiance (accuracy) or less. The Standard for Measuring Distance/Target Size Values for Quantitative Thermal Imaging Cameras provides a simple procedure for accurately calculating spot ratio values for imaging radiometers. To obtain a copy, contact Infraspection Institute at 609-239-4788 or visit the Standards section of the Infraspection Online Store.
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Infrared Prior to PM Shutdowns
Many facilities undergo regularly scheduled shutdowns for preventive maintenance. Performed prior to shutdowns, infrared inspections can help to point out potential problems in electrical and mechanical systems and allow for more effective use of resources during a shutdown.
When planning a scheduled outage, it is a good practice to perform infrared inspections four to six weeks prior to the outage. Doing so can uncover hidden problems and allow for scheduling of additional requisite manpower and/or obtaining replacement parts prior to the shutdown. Infrared inspections can also save money by helping to direct maintenance efforts where they will be most needed during the planned outage.
Pre-outage infrared inspections should be performed with subject equipment energized and operating under normal load. Inspections should be performed by trained and certified thermographers who are familiar with the equipment being inspected. A follow-up infrared inspection of all repaired/retrofitted equipment should then be performed within 48 hours of repair or installation to confirm that repairs were effective.
For more information on thermographer training and certification, or to obtain a copy of the Standard for Infrared Inspection of Electrical Systems and Rotating Equipment, please contact Infraspection Institute at 609-239-4788 or visit us online at www.infraspection.com.
Tornado Safety
Tip written by: Infraspection Institute
With the onset of warm weather, tornado season has arrived. In an average year, tornadoes in the US cause 80 fatalities and 1500 injuries. Knowing what to do before and during a tornado is crucial for survival.
Tornadoes are nature’s most violent storms. Spawned from powerful thunderstorms, tornadoes can cause fatalities and devastate a neighborhood in seconds. A tornado appears as a rotating, funnel-shaped cloud that extends from a thunderstorm to the ground with whirling winds that can reach 300 miles per hour. Damage paths can be in excess of one mile wide and 50 miles long. Every state is at some risk from this hazard.
Some tornadoes are clearly visible, while rain or nearby low-hanging clouds obscure others. Occasionally, tornadoes develop so rapidly that little, if any, advance warning is possible. The best defense against tornadoes is to be alert to weather conditions and be ready to seek shelter.
Before a tornado, be alert to changing weather conditions.
- Listen to NOAA Weather Radio or to local newscasts for the latest information
- Watch for approaching storms
- Know the danger signs: Dark, often greenish sky; large hail; large, dark, low-lying or rotating clouds; loud roar, similar to a freight train
If you see an approaching tornado or are under a tornado WARNING, seek shelter immediately.
- If you are in a structure, go to a pre-designated shelter area or the center of an interior room on the lowest building level. Get under a sturdy table and use your arms to protect your head and neck. Do not open windows.
- If you are in a vehicle, get out immediately and go to the lowest floor of a sturdy, nearby building or a storm shelter. Mobile homes, even if tied down, offer little protection from tornadoes.
- If you are outside with no shelter, lie flat in a nearby ditch or depression and cover your head with your hands. Beware of flying debris and the potential for flooding.
For more information on tornadoes and tornado safety, visit the NOAA website.
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Normal Hot Spots in Electrical Systems
In general, hot spots within electrical systems are indicative of problems such as loose connections or overloaded circuits. For some electrical components, high temperature operation is normal and an infrared imager can be used to help ensure that these devices are functioning.
During a routine infrared inspection of electrical distribution systems, similar components under similar load are compared to each other. Items appearing inexplicably hot are reported as exceptions to be further investigated and appropriately repaired. For components that normally operate at elevated or high temperature, a lack of heat may be indicative of an exception.
Capacitors used for power factor correction are good examples of components that are normally warm. Properly functioning capacitors should operate above ambient temperature and their casings should be uniform in temperature when compared to similar units under similar load.
Thermal overload relays are found in many motor controllers. The elements of these relays, often called heaters, may operate at high temperature when the circuit is under load. When compared to adjacent phases, these elements should be similar in temperature with no pronounced hot spots.
Electric strip heaters are used to control humidity within switchgear enclosures. Switchgear heaters usually operate at very high temperatures and their operation can easily be verified with an infrared imager. Cold strip heaters may be indicative of a failed element, improper control settings, or a de-energized control circuit.
The above are just three examples where elevated temperatures are normal. Thermographers should always be on the lookout for cold spots that may be indicative of problems in addition to hot spots traditionally associated with exceptions.
Infrared inspection of electrical 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.
How to Calculate Emittance
Tip written by: Infraspection Institute
Utilizing correct emittance values is imperative for accurate non-contact temperature measurements. Knowing how to accurately calculate emittance values can help to ensure the accuracy of infrared temperature measurements.
Although thermographers frequently obtain emittance values from published tables, this practice can introduce significant errors. Following the procedure listed below, it is possible to accurately calculate the E value of an object.
Equipment Required:
- Calibrated imaging radiometer with a computer that allows thermographer to input Reflected Temperature and Emittance values
- Natural or induced means of heating/cooling target to a stable temperature at least 10ºC above/below ambient temperature
- Calibrated contact thermometer
Method:
- Place imaging radiometer at desired distance from heated/cooled target. Be certain that target is larger than imager’s spot measurement area. Aim and focus imager on target
- Measure and compensate for Reflected Temperature
- Place imager crosshairs on target
- Use contact thermometer to measure target temperature at location of imager crosshairs. Remove contact thermometer
- Without moving imager, adjust E control until observed temperature matches value obtained in Step 4 above. The displayed E value is the Emittance value for this target with this imaging radiometer. For greatest accuracy, repeat above three times and average the results.
Note: This procedure requires contact with the object being measured. Be certain to observe all necessary safety precautions prior to making contact with target.
The above procedure is described in detail in the Standard for Measuring and Compensating for Emittance Using Infrared Imaging Radiometers. Copies of the Standard are available from the Infraspection Online Store or by calling 609-239-4788.
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Defining the Ideal IR Reporting Software
As thermography has matured, thermal imaging equipment has become more sophisticated and user friendly. During the past 20 years, manufacturers have developed software that enables thermographers to post process their captured imagery. Typical features include the ability to change color palettes, temperature measurement tools, and the option to change level and gain.
Because thermal imager manufacturers concentrate their expertise on hardware development, they tend to focus on image processing and largely ignore reporting. In fact, most software packages include only rudimentary templates for creating hardcopy reports. These templates are geared to a single application and do not permit the user to create a complete inspection report. The result is that thermographers must utilize multiple, separate software programs thereby wasting a huge amount of time and money.
A recent survey of practicing thermographers found that the perfect infrared reporting software would:
- Be easy to use
- Work with all thermal imagers
- Quickly generate standards-compliant reports
- Work with all computer operating systems
- Contain preformatted templates for common applications
- Maintain imagery and inspection routes
Responding to the challenges faced by practicing thermographers, T/IR Systems LLC developed the world’s first cloud-based infrared report writing and data management software that works with all thermal imagers.
Designed by expert thermographers and personnel from Infraspection Institute, TI Reporter™ allows you to generate standards-compliant reports for a wide variety of applications. Simply complete the preformatted templates following the on-screen prompts and add your images.
Utilizing cloud technology, TI Reporter™ offers unmatched mobility and data management. There is no software to install or update and users always have access to the latest version of the software. TI Reporter™ contains several preformatted report templates that are compliant with reporting requirements of published industry standards. Templates are available for infrared inspections of electrical systems, mechanical systems, building envelopes, steam and piping systems, flat roofs, and to detect pests. Customized templates are available upon request.
For more information or to try TI Reporter™ for free, visit www.ti-reporter.com today.
Measuring and Compensating for Reflected Temperature – Part 1
Tip written by: Infraspection Institute
Non-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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Measuring and Compensating for Reflected Temperature – Part 2
Tip written by: Infraspection Institute
Non-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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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.
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.
IR Inspections of Furnace Tubes
Tip written by: Infraspection Institute
Process furnaces or heaters are a critical component found in many petrochemical refineries. Performed properly, infrared inspections of furnace tubes can provide valuable data regarding tube condition and operating temperature.
Process heaters are large, refractory-lined structures used to heat hydrocarbon product during refining. Process heaters are similar to steam boilers in their construction except that hydrocarbon is passed through the firebox tubes instead of water. Safe operation of process heaters requires that tubes operate below their maximum operating temperature. Overheating of tubes can reduce operational life or lead to catastrophic failure.
Measuring tube temperatures is difficult for many reasons. Tubes are often remotely located from inspection ports and are frequently obscured by visually opaque flames. High temperature environments make contact measurements difficult or impossible. Under the right circumstances, infrared thermography can be used to provide qualitative and quantitative data for in-service heater tubes. The following images were taken through viewports on operating heaters.
Image taken through opaque flame.
Image taken through opaque flame.
Infrared inspection of process furnaces or heaters is one of the most difficult tasks for thermal imaging and infrared radiometry. Accuracy in temperature measurement is of paramount importance since many companies utilize infrared data to determine safe operating limits for in-service heaters.
Far from being a “point and shoot” application, a thermographer needs to understand heater operation and heat transfer as well as issues pertinent to thermography. These include, but are not limited to: infrared camera selection including proper spectral response and spot measurement size; imager calibration; use of filters, windows and heat shields; calculating emittance and reflected temperature; equipment precision and accuracy; and how to obtain reliable reference temperatures to verify proper imager settings.
To help ensure accuracy, thermographers should be trained to at least Level II and, when possible, work with an experienced mentor until they have gained sufficient field experience.
Infrared inspection of process heater tubes is one of the applications covered in the Infraspection Institute Level II Certified Infrared Thermographer® training course. For more information or course schedules, visit us online at www.infraspection.com or call us at 609-239-4788.
More information on this subject is available via a free download from our website at: Applications of Infrared Thermography for Petrochemical Process Heaters.
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Infrared Inspections of Arc Fault Circuit Interrupters
Tip written by: Infraspection Institute
Excess heating is often a sure sign of defective electrical equipment; however, the absence of heat can also be a sign of component failure. In this Tip, we demonstrate how thermal imaging may be used to detect defective Arc Fault Circuit Interrupters.
An Arc Fault Circuit Interrupter (AFCI) is an advanced type of electrical circuit breaker that automatically opens a circuit when it detects a dangerous electrical arc on the circuit it protects. Designed to help prevent electrical fires, an AFCI can sense between electrical arcs caused by defective equipment versus those associated with the normal operation of devices such as light switches.
In order to monitor for dangerous electrical arcing on a circuit, AFCI devices have electronic circuitry built into them. This circuitry can cause the body of the AFCI to run several degrees warmer than ambient temperature. Depending upon the settings of your thermal imager, these devices may show a marked contrast to their surroundings.
When thermographically inspecting AFCI devices, be sure to inspect the line and load side connections at the AFCI device as well as the neutral bus bar connection for the subject breaker. Should you find an AFCI device that is operating close to ambient temperature, it is likely that the internal circuitry has failed making the device incapable of protecting against arc faults. Such devices should be further tested and replaced if they are found to be defective.
Infrared inspection of electrical 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.
Building Envelope Inspections – Which Way Do We Go?
Tip written by: Infraspection Institute
Infrared inspections of building envelopes have many uses. Of paramount importance is a logical inspection route that covers all subject areas and provides report data that can be easily followed.
Infrared inspections of building envelopes may be performed to detect evidence of thermal deficiencies and/or latent moisture. Typically, infrared inspections cover the exterior walls, windows, doors, and ceilings or roof of the structure. Depending upon the reason for the inspection, the inspection may be performed from either an interior or exterior vantage point. Regardless of vantage point, complete coverage of all subject surfaces is critical to inspection success.
One method of helping to ensure complete coverage is to begin the inspection at a recognizable reference point such as a main doorway or other easily identified feature. From this starting point, the inspection is conducted for all subject surfaces of the building while moving in a clockwise fashion.
Moving in a clockwise fashion allows a thermographer to move in a logical and predetermined fashion around the building. This practice will work equally well when working from either the interior or exterior of the building. When thermal imagery is recorded to video, clockwise routes can help a viewer to better understand recorded data when viewing the video record at a later time.
The topic of infrared inspections of building envelopes is covered in all Infraspection Institute Level I training courses. For more information on thermographer training or to obtain a copy of the Standard for Infrared Inspection of Building Envelopes, contact Infraspection Institute at 609-239-4788 or visit us online at www.infraspection.com.
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Ladder Safety – Part 1
Tip written by: Infraspection Institute
For many thermographers, ladders provide a means for accessing remote areas and equipment. Taking the time to use ladders properly can help to prevent serious or fatal injuries.
According to OSHA, falls from portable ladders are one of the leading causes of occupational fatalities and injuries. When using portable ladders, always keep the following points in mind:
- Avoid electrical hazards. Look for overhead power lines before handling a ladder.
- Inspect ladders before each use. Remove broken ladders from service and repair or discard.
- Do not exceed ladder load rating. Be aware of user’s weight including tools.
- Use a ladder only on a stable, level surface. Do not stack ladders on boxes, barrels, or unstable platforms to gain additional height.
- Maintain a 3 point contact with ladder (two feet, one hand). Always face the ladder when climbing and keep your body centered between the rails.
- Ladders should be free of slippery material on rungs, steps or feet.
- Never stand on the top step or rung of a ladder unless it is designed for this purpose.
Lastly, permanent ladders should be checked prior to use to ensure that they are securely attached to their structure.
Thermographer safety is one of the 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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Ladder Safety – Part 2
Tip written by: Infraspection Institute
For many thermographers, ladders provide a means for accessing remote areas and equipment. In this week’s Tip we cover safety tips applicable to extension ladders.
According to OSHA, falls from ladders are one of the leading causes of occupational fatalities and injuries. When using portable extension ladders, always keep the following in mind:
- Avoid electrical hazards. Look for overhead power lines before handling a ladder.
- Inspect ladders before each use. Remove broken ladders from service and repair or discard. Use a ladder only on a stable, level surface. Do not stack ladders on boxes, barrels, or unstable platforms to gain additional height.
- Extension or straight ladders used to access an elevated surface must extend at least 3 feet above the point of support. Never stand on rungs above the point of support.
- The proper angle for setting up a ladder is to place its base one quarter of the working length of the ladder from the wall or other vertical surface.
- Be certain that all locks on an extension ladder are properly engaged.
- Do not exceed ladder load rating. Do not move or shift a ladder while a person or equipment is on the ladder.
Lastly, a ladder placed in any location where it could be displaced by other work activities must be secured to prevent displacement or a barricade erected to keep traffic away from the ladder.
Thermographer safety is one 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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The Problem with Solar Loading
Tip written by: Infraspection Institute
Everyone who has performed infrared inspections outdoors on sunny days is familiar with the problem of solar reflections. Compensating for solar reflections is usually accomplished by repositioning the thermal imager to change the viewing angle to eliminate the reflection. For objects exposed to strong sunlight, a more insidious problem can occur in the form of solar loading.
The concept of solar loading is familiar to everyone: objects exposed to the Sun will heat up. In general, dark colored objects absorb the most solar energy and heat faster than light colored objects. If an object absorbs enough heat from the Sun, significant thermal anomalies may be hidden and go undetected.
As there is no way to compensate or correct for solar loading, the most prudent course of action is avoidance. Solar loading can be avoided by imaging on cloudy days, at night, or early in the morning. Solar loading can also be overcome by shading an exposed target and waiting for the object’s temperature to return to normal.
Identifying and overcoming environmental error sources such as solar loading is one of the many topics covered in depth within the Infraspection Institute Level I Certified Infrared Thermographer® training course. For more information on course dates or to register for a course, call 609-239-4788 or visit Infraspection Institute online.
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Setting Temperature Limits
Over the past thirty years, a number of temperature severity guidelines have been published by various organizations. When using these guidelines, you may compare similar components under similar load to each other OR compare the subject component to ambient. The former of these approaches is recommended since ambient temperature can swing widely over time. Furthermore, it is often impossible to obtain an accurate ambient temperature for devices located within an enclosure once the enclosure has been opened for the infrared inspection.
One of the most conservative temperature guides can be found in the Standard for Maintenance Testing Specifications, published by the InterNational Electrical Testing Association, Portage, Michigan. According to the NETA MTS, temperature differentials greater than 15° C are categorized as, “Major discrepancy; repair immediately”.
Other organizations publish less conservative temperature guidelines than the NETA MTS. Some guides require delta T’s of 70°C or higher to qualify as items of immediate concern. When setting temperature limits, one should remember that temperature differentials cannot be utilized to predict time to failure for an electrical device. Therefore, all thermal anomalies detected during an infrared inspection should be investigated and proper corrective measures undertaken as soon as possible.
Setting temperature limits and prioritizing exceptions for electrical and mechanical equipment are two of the many topics covered in the Level II 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.
IR Inspections of Smooth Surfaced Roofs
Tip written by: Infraspection Institute
Having the right tool for the job is often essential for success. When performing infrared inspections of smooth-surfaced roofs, a short wave thermal imager can significantly outperform a long wave imager.
Smooth-surfaced roofs, both single-ply and built-up, can present significant challenges during an infrared inspection due to reflectivity of the roof membrane. Should reflectance be sufficiently high, areas of latent moisture may be undetectable to a thermal imager.
Most infrared inspections of flat or low slope roofing systems are conducted at night by walking across the roof surface using a handheld thermal imager. This technique often results in a relatively shallow viewing angle thereby lowering the emittance of the subject roof membrane.
Depending upon site conditions and roof materials, roof membranes can appear to be as reflective as polished metal surfaces. Membrane reflectivity will be especially noticeable on cool, clear nights that permit the cold night sky to be reflected from the roof surface. It will also be significant on roofs that have been coated with aluminum paint.
To this day, the most practical way to deal with the reflectivity of smooth roof membranes is to utilize a thermal imager with short wave (2 to 5.6 micron) spectral response. This will help to eliminate reflections from the roof and can significantly increase inspection accuracy. Although long wave imagers can be used for smooth membranes, they can significantly understate the size of moisture-damaged areas or miss them entirely.
Infrared inspections of low slope roofs is one of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. 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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The Tortoise and the Hare
Everyone has heard the fabled race between the tortoise and the hare in which the tortoise beats the hare. One of the morals of the story is that a steady pace may be more fruitful than erratic bursts of speed.
Thermographers who perform infrared inspections should keep in mind that a slow and steady pace can lead to victory. Working at an even pace can help to prevent overlooking the subtle temperature variations that often indicate serious problems. Purchasers of thermographic services should bear in mind that the best value is not in the fastest inspection time, but rather in the thoroughness and accuracy of the inspection.
When it comes to your next infrared inspection, beware of the hare. Inspections that are praised more for their swiftness today may be cursed in the future for their costly oversights.
Properly conducting an infrared inspection is one of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. For course locations and dates or information on our Distance Learning courses, visit us online at: www.infraspection.com or call us at 609-239-4788.
A Hidden Danger in Electrical Systems
Tip written by: Infraspection Institute
Although thermography is a non-contact test, preparing for an infrared inspection of electrical equipment often requires manual preparation of switchgear components. Unwary thermographers and their assistants can be injured by making contact with cabinets or component surfaces that have become accidentally or unintentionally energized.
Switchgear enclosures and components are generally designed to prevent their surfaces from becoming energized. Under certain circumstances, switchgear enclosures and other dielectric surfaces can become unintentionally energized to significant voltage levels. This potentially lethal condition may be caused by improper wiring, faulty equipment, or contamination due to dirt or moisture.
The image below shows a potential of 265 volts AC between a molded case circuit breaker and ground. This condition was discovered after an unprotected worker received a shock by touching the phenolic breaker handle.
Whenever working on or near energized electrical equipment, keep the following in mind:
- Only qualified persons should be allowed near energized equipment
- Treat all devices and enclosures as though they are energized
- Never touch enclosures or devices without proper PPE
- Do not lean on or use electrical enclosures as work tables
- Always follow appropriate safety rules
- Know what to do in case of an accident
Remember ~
There are old thermographers and
There are bold thermographers; however,
There are no old, bold thermographers.
Thermographer safety 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 or call us at 609-239-4788.
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Splash Protection for Your IR Imager
Taking your infrared imager into dusty or wet environments can have disastrous consequences for your imager. While it is best to wait for such conditions to subside, you can use a polyethylene sheet or trash bag to temporarily protect your imager and accomplish a qualitative inspection.
Since not all imagers and trash bags are created equal, you can follow the following steps to ensure good results.
- Set up imager looking at a thermally stable target with a high emittance. If using an imaging radiometer, note the apparent temperature of the target.
- Select a clean, unused, polyethylene trash bag with a uniform thickness.
- Open trash bag and place over imager. Use only a single layer of the bag plastic to cover the lens.
- Use a rubber band to keep plastic smooth and wrinkle free over the imager lens.
- Image target in Step 1 again and note image quality and apparent temperature.
- Repeat above steps using different brand bags and thicknesses until you find a bag that gives minimal attenuation of image and apparent temperature.
- After selecting the bag that works, trim to fit imager so as to prevent a tripping hazard. If your imager requires air cooling, leave the bottom of the bag open so the imager can ‘breathe’.
- When finished imaging, remove bag from imager and discard.
While not glamorous, this procedure can allow you to successfully perform a qualitative inspection in an environment that might otherwise harm your imager.
Infrared equipment selection and operation are two of the many topics covered in all Level I Infraspection Institute Certified Infrared Thermographer® training courses. Level I training is available at several locations each month and through our Distance Learning Program. For information on thermographer training including course locations and dates, visit us online at www.infraspection.com or call us at 609-239-4788.
Infrared Inspections of Conveyor Bearings
Tip written by: Infraspection Institute
If your facility utilizes conveyor systems for moving product, you may be able to use your thermal imager to locate defective bearings.
Many conveyor systems utilize a large number of rolling element bearings to support rollers or conveyor belting. Depending upon the size of the facility, a conveyor system may contain thousands of rolling element bearings. Due to the vast number of bearings, inspecting them can be an enormous and time consuming task.
Because bearing wear is usually accompanied by a rise in temperature prior to failure, infrared imaging can be used to detect overheating bearings. The infrared inspection is performed by comparing similar bearings under similar load. Bearings appearing inexplicably warm can be noted for further investigation.
When performing your infrared inspection, bearings should be operating at normal speed and you must have line-of-sight access to the subject bearings. Since the infrared inspection is performed from ground level without special preparation, the inspection can be performed quickly.
When performed by an experienced, certified thermographer, infrared inspections can provide a cost effective method for helping to eliminate unexpected failures and improving your production uptime.
Infrared inspection of bearings 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 4, 2023
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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 11, 2023
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Understanding Radiance
Keeping it simple is a principle for effective communications. When it comes to infrared thermography, oversimplification can be detrimental when it leads to confusion or misunderstandings.
In trying to explain the operation of thermal imagers, many will frequently state that infrared imagers sense temperatures across the surface of objects. While this may allow a layperson to grasp the concept of infrared equipment operation, it can foster a basic misunderstanding that can lead to significant diagnostic errors.
Infrared imagers do not sense temperature. Rather, they directly sense infrared energy radiated from the surface of an object. Using sophisticated on-board computers, radiant energy is converted to a monochrome or multi-colored image that represents the apparent thermal patterns across an object’s surface.
Emissivity is the most significant characteristic influencing the amount of energy radiated by an object. Emissivity is a dynamic phenomenon that is influenced by many factors; the relative amount of energy radiated by an object is described by its emittance.
Emittance is a number between 0 and 1 that numerically expresses how well an object radiates infrared energy when compared to a blackbody at the same wavelength and temperature. The emittance of an object will vary with temperature, shape and surface condition. In thermography, emittance can be further influenced by viewing angle and the spectral response of the imager/radiometer utilized.
In order to ensure accuracy, it is imperative for a thermographer to understand the concepts of radiance and the principles of non-contact temperature measurement. Anything that affects emissivity will influence both qualitative and quantitative data.
For over 35 years, Infraspection Institute’s Certified Infrared Thermographer® training courses have set the industry standard for excellence. Our Certified Infrared Thermographer® and applications courses combine infrared theory with practical, real-world approaches that enable students to quickly master skill sets that help to ensure accuracy. All courses are taught by field-experienced practicing thermographers. For more information or to register for a class, call 609-239-4788 or visit us online at www.infraspection.com.
September 18, 2023
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Scheduling IR Equipment for Maintenance
Many thermographers think of the holidays as a time for family, festivities and annual maintenance of their infrared equipment. Planning ahead can help to minimize imager downtime and avoid or minimize program interruption.
Because infrared test equipment plays a key role in an inspection program, minimizing downtime required for service is imperative. Keeping the following in mind can help routine service to proceed more smoothly and ensure a faster turnaround for your imager.
- Schedule routine equipment service and/or calibrations well in advance
- Most service departments require you to obtain a Return Authorization before shipping equipment
- Be sure to include all optics and filters when shipping your system
- Consider scheduling service before or after holidays to avoid service backlogs
- Arrange for replacement equipment if you anticipate a long delivery time for service
When shipping your equipment, enclose a letter stating services required and any problems with the subject equipment. Be sure to affix a Packing List to the exterior of your shipping container noting descriptions and serial numbers of items shipped. Lastly, don’t forget to ascertain Customs requirements if your equipment must be shipped outside of your country for service.
Infrared equipment selection and operation are two of the many topics covered in all Level I Infraspection Institute Certified Infrared Thermographer® training courses. Level I training is available at several locations each month and through our Distance Learning Program. For information on thermographer training including course locations and dates, visit us online at www.infraspection.com or call us at 609-239-4788.
September 25, 2023
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Autumn IR Inspections to Assess Roof Condition
Tip written by: Infraspection Institute
With 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.
Infrared Inspection of Load Break Elbows
Tip written by: Infraspection Institute
Load break elbows are a common feature on shielded cables. Thermography may be used to provide evidence of loose or deteriorated connections associated with these connectors.
Load break elbows are insulated plug-type terminals typically used to terminate shielded, underground cables. Load break elbows act as large power plugs for connecting cables to transformers, switching cabinets and bushings equipped with load break receptacle bushings.
Internal to load break elbows are several mechanical connections each of which is subject to deterioration over time. A typical elbow contains a crimp connection and a pin electrode that screws into the elbow. During normal operation, this pin electrode mates with a receptacle which also contains mechanical connections. Elbows and receptacles that have loose or deteriorated connections will operate at elevated temperatures and are readily detectable with a thermal imager.
~ Images courtesy Jim Lancaster
Normally, all electrical connections within an elbow are hidden from view due to the elbow’s molded rubber insulating body. Due to their high emittance, load break elbows are excellent candidates for infrared inspections. In fact, thermal imaging is one of the best ways to inspect these components for the integrity of their connections.
Since line-of-sight access to the electrical connections within load break elbows is not possible, temperatures at the point of origin are likely to be much hotter than observed temperature values on the exterior surface. Small Delta T’s observed on the surface of elbows can be indicative of a serious problem. Because of this, hot load break elbows should be investigated for cause as soon as possible and appropriate corrective measures taken.
Infrared inspection of power distribution systems is one of the many topics covered in all Infraspection Institute Level I training courses. For information on course locations and dates or our Distance Learning Courses, visit us online at www.infraspection.com or call us at 609-239-4788.
Training – A Wise Use of Year End Budget Money
Tip written by: Infraspection Institute
When 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 instruction
Infraspection 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.
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October 16, 2023
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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 Tip, 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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October 23, 2023
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Using an Auto Image Function
Auto Image is a feature found on many modern thermal imagers. While this feature may be helpful in certain imaging situations, its usage can cause thermographers to overlook significant thermal anomalies.
Humans have come to rely on technology to make our lives easier. We frequently take for granted how many mundane chores of the past have been automated. Each day we rely upon automatic transmissions in our cars, auto correction in word processors, and auto flush in lavatories. As infrared imaging has matured, automatic image adjustment has become a common feature on thermal imagers.
Auto Image, also known as auto adjust, is a feature commonly found on today’s thermal imagers. When engaged, the thermal imager will automatically adjust Level and Gain values so that the coldest and hottest objects within the imaged scene will be set as the lowest and highest temperature limits respectively. Auto Image may be for a single frame or it may allow for constant adjustments to automatically take place in real time.
While single-frame auto image may provide a good starting point for level and gain settings, full time usage of auto image will cause level and gain values to constantly change as the imager is panned across a given target. With values constantly changing, it is nearly impossible to make comparisons between imaged objects since there is no fixed, baseline value. In addition to making thermal imaging confusing, the use of fulltime auto image will cause many thermal anomalies to go undetected.
Thermographers who own thermal imaging equipment should familiarize themselves with their equipment to determine if their imager features automatic image mode(s). For imagers featuring single frame auto, a thermographer may use this feature to allow the imager to ‘suggest’ initial level and gain settings. For scenes that do not have a wide variation in temperature such as building envelopes or roofs, auto image may provide optimal imagery. If not, the thermographer should then manually adjust the imager’s level and gain settings in order to optimize the displayed image.
For thermal imagers that do not have onboard level and gain controls or for those that feature full-time auto image, the technique for optimizing the displayed image is as follows:
- Set imager to Auto Image mode
- Aim and focus imager on item of interest
- Pan imager slightly to obtain optimal contrast within scene
- Immediately switch to Manual mode to lock range/level settings
- If possible, adjust range and level controls to further optimize displayed image
With the above steps completed, the thermographer may continue imaging similar objects under similar conditions. Should scene conditions change, the above steps may be repeated as necessary.
Properly adjusting level and gain is an extremely important part of thermal imaging. For best results, a thermographer should never rely on full time auto image to provide optimal imagery.
Thermal imaging selection and operation are two of the many topics covered in all Infraspection Institute Level I training courses. For course locations and dates or information on our Distance Learning program, visit our website or call us at 609-239-4788.
October 30, 2023
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Autumn is the Time for Steam Trap Testing
Tip written by: Infraspection Institute
With 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 our Distance Learning Courses, visit us online at www.infraspection.com or call us at 609-239-4788.
November 6, 2023
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Understanding Imager Resolution
Tip written by: Infraspection Institute
Resolution is one of the most important objective specifications for a thermal imaging system. Due to a lack of standardization, this term is used in a variety of ways, many of which can be confusing or misleading.
Simply stated, resolution describes the capability of a thermal imager to clearly depict a target. Imager resolution is determined by an interdependent set of circumstances, the most important of which are described below.
- Detector: Some manufacturers offer total pixel count of the detector as a measure of resolution. Resolution generally increases with the number of pixels; however, pixel viewing angle (IFOV) also affects detector resolution. Meaningful IFOV data are frequently unavailable.
- Optics: Changing lenses affects an imager’s ability to clearly resolve a target at a given distance. Generally, telescopic lenses increase optical resolution; wide angle lenses decrease resolution.
- Signal-to-noise ratio: Generally, higher ratios equate to increased image resolution. Imagers with poor ratios will provide imagery that is grainy, thereby compromising image quality.
- Display Monitor: To maximize performance, the pixel count of an imager display monitor should equal, or exceed the number of detector pixels. Compact or monocular displays can severely limit resolution. Use of a high resolution monitor cannot compensate for low detector resolution.
When considering an imager for purchase, be certain to try the imager under the same circumstances that you will encounter in the future. Because there is no objective method to determine imager resolution, one should physically compare subject imagers to each other.
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November 13, 2023
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IR Inspections of Timber Framed Buildings
Tip written by: Infraspection Institute
Well known for its ruggedness and distinct architectural features, timber frame construction is a popular choice for commercial and residential buildings. Used properly, thermal imaging can be used to detect evidence of excess energy loss within these unique structures.
Timber framing is a building construction method that utilizes heavy, squared-off timbers rather than dimensional lumber such as 2x4s. Timbers are carefully fitted and secured using mortise-and-tenon joints often held together by large wooden pegs. The use of timber framing was common for wooden buildings constructed in the 19th century and earlier.
When utilizing timber frame construction for conditioned buildings, particular attention must be paid to the construction of exterior walls and the roof to minimize air leakage. Failure to do so can result in significant comfort and performance issues. The dark areas in the thermal image below are the result of significant air leakage within a timber framed building.
In addition to detecting air leakage sites, thermal imaging can also reveal energy loss due to missing, damaged, or misapplied insulation. The thermal image below shows an exterior wall and roof of a timber framed building where traditional framing was used for sidewall and roof construction. The dark areas show significant energy loss.
For best results, thermal imaging of timber framed buildings should be performed from the inside of the building when there is an inside/outside temperature differential of at least 10 Celsius (18 F) degrees. Thermal imaging may be performed under natural conditions or while the building is depressurized. Imaging should be scheduled to avoid errors due to solar loading of the building’s walls and roof.
Infrared inspections of building envelopes 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 Building Envelopes, visit us online at www.infraspection.com or call us at 609-239-4788.
November 20, 2023
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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, 2023
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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.
