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.
