2020
How Dust Creates Full Size Thermal Imagery
Tip written by: Infraspection Institute
When performing an infrared inspection of the interior of a building, you may be able to visually observe full-size thermal images without your thermal imager. The cause of this phenomenon is simple dust and dirt normally found within most buildings.
Many buildings employ cavity wall details in the construction of interior spaces. When the exterior of framed walls are exposed to cold temperatures, areas with diminished R values will cause the interior surfaces of the wall to cool. Such cold areas may be caused by framing members or wall cavities with missing or damaged insulation.
If interior humidity levels are high and outdoor temperatures sufficiently low, moisture will condense on the wall surfaces within the occupied spaces. Once moisture condenses on the wall surfaces, dust and smoke particles can collect in these areas and will remain once the wall surface has dried.
Thermal patterns caused by dust and condensation are readily observed for light-colored walls with smooth surfaces such as drywall coated with smooth latex paint. The intensity of the resulting dust patterns will be dependent upon humidity levels, wall temperatures, and the amount of particulates within the air.
Typically dust patterns are more intense within areas occupied by smokers, within kitchens, near woodstoves or fireplaces, or in areas where candles are burned. Over time, dust patterns can become quite pronounced and will often clearly show every framing member and insulation deficiency within the wall.
Infrared inspection 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 including course locations and dates, visit us online at www.infraspection.com or call us at 609-239-4788.
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January 27, 2020
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Inspecting Service Entrance Cables
When performing infrared inspections of electrical systems, many thermographers tend to focus their attention on outdoor substations and overhead electric lines. Unexpected failures can occur when service entrance cables are overlooked.
Service entrance cables provide a critical link between outdoor electric supply and a building’s indoor electrical equipment. Like other parts of the electrical system, these conductors are subject to loose or deteriorated connections which can cause unexpected interruptions in electrical power. Fortunately, such loose connections can often be detected with a thermal imager.
When inspecting service entrance cables, one should bear the following in mind:
- Prior to inspection, ascertain that service cables are under adequate load
- When possible, inspect cable connections at both ends. Emissivity issues aside, in most cases connections should be the same temperature as cable conductors
- On long cable runs, be certain to inspect any inline splices for hotspots
- To avoid the effects of solar loading, inspect cable assemblies early in the morning, on a cloudy day or at night
Because it is impossible to predict time to failure based upon temperature, inexplicable temperature rises should be investigated for cause as soon as possible. Doing so can help to avoid unexpected downtime and improve the reliability of a facility’s electrical distribution system.
Infrared inspection of electrical 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 3, 2020
Sponsored by:
Selecting an IR Training Firm
Tip written by: Infraspection Institute
As thermography has gained in popularity, the demand for training services has also increased. Since operator training can have a profound effect on the success of an infrared program, obtaining quality training is of paramount importance.
At present, there are several firms that offer infrared training and certification. While nearly all infrared training firms refer to their training courses by level (1, 2, or 3), there are no standards which dictate the content of any offered course. As a result, training courses can vary widely between firms.
When choosing an infrared training firm, be certain to:
- Examine course curriculum to ensure that it meets one’s needs
- Ensure that course will be germane to all infrared imagers, regardless of age
- Ascertain if Certification is included with course, its expiration date, and renewal fees
- Determine number of years training firm has been in business – not the cumulative total of staff years
- Insist that instructors be practicing thermographers with documentable field experience in their area of instruction
Lastly, beware of claims that training is “vendor neutral”. It is impossible for training firms to sell infrared equipment or train for equipment manufacturers without being biased. Firms who train for manufacturers work for manufacturers and cannot provide the unbiased information students deserve. Simply put, no man can serve two masters.
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. All courses are taught by practicing, expert Level III thermographers whose field experience is unsurpassed anywhere in the world. We teach effective, real-world solutions using the latest standards, software and technology. For more information call 609-239-4788 or visit us online at www.infraspection.com.
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February 10, 2020
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Detecting Underground Pipe Leaks
Leaks are a common problem with underground piping systems. Under the correct conditions, infrared thermography can help to detect evidence of leaks from buried piping systems that carry hot or cold product.
When a leak develops in a buried piping system, fluid is lost to the surrounding earth. If a leak from a heated or cooled piping system is sufficiently large, a temperature change will occur at the surface of the ground in the vicinity of the pipe leak.
Leaks from buried piping are generally characterized by amorphously shaped thermal anomalies that appear along the pathway of the subject piping system. The ability to detect a pipe leak will be influenced by several interdependent factors including, but not limited to: pipe operating temperature, pipe system construction, burial depth, amount of loss, soil type and moisture content, and ground cover.
Infrared inspections of buried piping systems are best performed late at night with calm wind conditions. Inspections may be performed on foot, from a motor vehicle or from an aircraft. Performing the inspection late at night will eliminate the effects of solar loading and solar reflection.
During the inspection, the thermal imager is maneuvered over the pathway of the pipeline. Well-defined straight lines that correspond to the location of the buried lines generally indicate a healthy piping system. Amorphously shaped thermal anomalies that cannot be explained in terms of piping system construction or features may be indicative of pipe leaks and should be marked and subsequently investigated for cause.
Infrared inspection of underground piping systems is one of the many topics covered in all Infraspection Institute Level I training courses. For class locations and dates or information on our convenient, Distance Learning courses, visit us online at www.infraspection.com or call us at 609-239-4788.
February 17, 2020
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Pricing Infrared Inspection Services
Tip written by: Infraspection Institute
A well-known Zen riddle is, “What is the sound of one hand clapping?” A perpetual thermographer’s enigma is, “What are infrared inspection services worth?” This week’s Tip addresses some key considerations when evaluating prices for infrared inspection services.
Better, faster, cheaper – these powerful words are often used in advertising when attempting to attract new customers. Unfortunately, they fail to address the issue of quality – often one of the most important aspects of professional services such as thermography.
In determining prices for any service, one must determine all costs associated with providing services to one’s clients within a given time frame along with the amount of profit desired. The sum of these numbers, divided by the number of billable hours or days that can be sold during the same time period will yield an hourly or daily price. Depending upon how a company is structured and the desired profit margin, these numbers can vary widely.
When considering pricing for infrared inspection services, ask yourself the following questions:
- What services or features are prospects willing to pay for?
- How will the offered services add value to your client’s operation?
- What unique advantages can your company provide?
Once you have established pricing and begun to market your services, be prepared to justify your prices to prospects. Clients will often spend more for services if they can be convinced that they will receive better quality and value. Consistently having the lowest price will not win every order and can compromise a company’s longevity.
Marketing of infrared inspection services is one of the many topics covered in the Level III Infraspection Institute Certified Infrared Thermographer® training course. For more information on infrared training and certification, please call 609-239-4788 or visit us online at www.infraspection.com.
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February 24, 2020
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How Close Do You Need to Be?
One of the most frequently asked questions in thermography is, “How close do I need to be to my target?” The answer depends upon target size and the type of data that are desired.
Appropriate distance is largely dependent upon three factors: target size, IR equipment optics, and detector resolution.
With qualitative thermal imaging, the maximum viewing distance is achieved where the object and any possible anomalies can be clearly resolved. If a target cannot be clearly distinguished, it will be necessary to move closer or to use a telephoto optic.
When using an imaging radiometer, obtaining accurate temperatures will require substantially shorter distances than those required for thermal imaging. Obtaining accurate quantitative data requires that the radiometer’s spot measurement size is smaller than the area being measured. If it is determined that the radiometer’s spot size is larger than the area being measured, it will be necessary to move closer or use a telephoto optic calibrated for the imager.
Because there is no method for correcting for errors caused by imaging at excessive distances from a target, it is imperative to always ensure appropriate distance prior to recording images.
Spot measurement size and its impact on accurate temperature measurement is one 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 Measuring Distance/Target Size Values for Infrared Imaging Radiometers, visit us online at www.infraspection.com or call us at 609-239-4788.
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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Ambient Temperature & Radiometer Accuracy
Tip written by: Infraspection Institute
Many who live in cold climates are in the habit of allowing their automobile to warm up before driving. For accurate temperature measurement, one should allow sufficient time for a radiometer to equalize with ambient temperature.
When performing non-contact temperature measurements, many thermographers correct for error sources due to emissivity, reflectivity and transmissivity. One error source that is often ignored is the temperature of the radiometer itself. Depending upon design, radiometer operating temperature can significantly affect measurement accuracy.
Radiometers are calibrated under controlled laboratory conditions at stable ambient temperatures. To help ensure measurement accuracy, quality radiometers are constructed with internal temperature sensors. These sensors allow the radiometer’s firmware to correct for operation at different ambient temperatures.
When performing non-contact temperature measurements, radiometers should always be allowed to stabilize with ambient air temperature. Additionally, one should ensure that the radiometer’s lens is clean and free of condensation.
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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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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Is Distance Learning Right For You?
Tip written by: Infraspection Institute
Advancements in technology have reshaped traditional approaches to education. Students are now able to study a wide variety of subjects, including thermography, from virtually anywhere in the world.
Distance learning may be defined as any situation where the student and the instructor are in physically separate locations. Distance instruction may be live or pre-recorded and can be delivered via video presentations, remote teleconferencing, and web-based presentations.
Distance learning provides several advantages over the traditional classroom setting. Chief among these are the elimination of travel costs, 24 hour availability, and increased convenience in scheduling. The availability of Distance Learning courses for thermography is particularly beneficial to thermographers with hectic schedules.
When selecting Distance Learning courses for thermography, be sure to determine the following:
- How and when is course delivered
- Length of course and curriculum
- What standards does course curriculum conform to
- Are experienced instructors available to answer questions
- Does course qualify toward thermographer certification
- Experience of training firm in providing thermographic instruction
Infraspection Institute offers a wide variety of Distance Learning courses for thermography. Courses include: Certification Prep, Applications and Industry-Specific Courses. All courses are ASNT compliant and are taught by Level III Infraspection Institute Certified Infrared Thermographers® each having over 20 years experience. For more information on Infraspection’s Distance Learning Courses, call us at 609-239-4788 or visit the Infraspection website.
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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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Detecting Defective Lighting Ballasts
Lighting ballast failure may present more than an inconvenience; in some cases, it may present a fire hazard. Under the right conditions, an infrared imager may be used to detect overheated ballasts.
Lighting ballasts are dry-type transformers commonly found within fluorescent and HID light fixtures. Because ballasts are usually direct-mounted to the interior of the fixture casing, surfaces adjacent to ballasts frequently operate at nearly the same temperature. In the case of fluorescent fixtures, ballasts are usually in direct contact with the top surface of the fixture.
Properly functioning ballasts will operate up to several degrees above ambient air temperature. Defects such as short circuits or defective wiring can cause a ballast to significantly overheat. If ballast temperatures are sufficiently high, a fire may result.
By using an infrared imager to inspect fixture surfaces adjacent to ballasts, it is possible to rapidly detect evidence of overheated ballasts. When applying thermal imaging to installed fixtures, keep the following in mind:
- Ascertain how construction of subject fixtures will affect observed temperatures
- Plan inspection to afford clear line-of-sight to fixture surface
- Ensure fixtures are properly lamped and under load during inspection
- Allow sufficient time for fixtures to achieve thermal equilibrium
- Investigate excessively warm fixtures for cause
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.
What is Image Fusion?
The more things change, the more they remain the same. This timeless observation is especially true when referring to the seemingly revolutionary image fusion feature found on some of today’s modern thermal imagers.
The fusion feature found on some modern thermal imagers is somewhat of a relic having been around since the early 1990’s. In simple terms, image fusion is a feature that allows a thermographer to produce composite imagery generated from a thermal image and a corresponding daylight image of the same subject.
Originally designed for the low-resolution imagers of the early 1990’s, composite imagery was achieved via a CCD camera affixed to the thermal imager. The thermal imager’s onboard computer was used to combine daylight and infrared imagery into a single image. During the 1990’s composite imagery did not gain significant market share and was all but forgotten with advances in imager resolution.
In 2006, some manufacturers began to offer composite imagery capabilities on modern imagers. The principle of modern composite imagery is largely the same as in years past; however, today’s imagery is vastly improved over yesteryear due to increased resolution of both thermal imagers and the daylight cameras featured on them.
By utilizing imager controls or software on composite-capable imagers, thermographers can select color palettes as well as the amount of image blending. Images may be stored to PC card or recorded to digital media in real time. The recent resurrection of composite imagery offers several advantages:
- More precise correlation of thermal data with daylight imagery
- Potential reduction in number of images required within hardcopy reports
- Ability to easily convey information to recipients of reports or imagery
Although features such as composite imagery can help to demystify thermal imaging, the proper conduct of an infrared inspection still relies upon a properly trained and experienced thermographer. For more information on thermographer training and certification, call Infraspection Institute at 609-239-4788 or visit us online at www.infraspection.com.
Imager operation is one of the many topics covered in all Infraspection Level I training courses. For more information on our Distance Learning Program or our open enrollment classes, visit us online at Infraspection.com or call us at 609-239-4788.
April 20, 2020
Sponsored by: Testo Inc.
Imager Resolution & The Great Pixel Debate
Tip written by: Infraspection Institute
Resolution is one of the most important objective specifications for any thermal imaging system. Pixel count is frequently offered as a measure of image quality; however, pixel count is only one of many factors that affect imager resolution.
The Focal Plane Array (FPA) detector assemblies used in modern infrared imagers are made up of several tiny, discrete picture elements or pixels. Each pixel is a discrete infrared detector that collects thermal data. Individual pixels are arranged to form an array that ultimately allows the imager to produce a thermal image.
FPA detectors are commonly specified according to pixel count and ratio. Typical detector sizes for industrial imagers range from 160W by 120H to 320W by 240H; some detectors may have more or less pixels. To determine the total pixel count for a detector; the horizontal and vertical values are multiplied.
Imager manufacturers often cite pixel count as a measure of imager resolution. Imager sales are won and lost as entire ad campaigns focus heavily on this single objective specification. Actually determining resolution is not that simple.
Although resolution generally increases with the number of pixels, there are several other factors that influence image clarity or resolution. These include, but are not limited to, pixel viewing angle, imager optics, signal-to-noise ratio and the imager’s display screen.
When evaluating an imager for resolution, physically try the imager under actual working conditions. Imagers that produce clear images should be sufficient to the task regardless of pixel count.
To better understand imager resolution, read the article, Selecting, Specifying and Purchasing Thermal Imagers available from Infraspection Institute. To obtain a copy of the article, call 609-239-4788 or visit us online at www.infraspection.com.
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The Power of Inductive Heating
The magnitude and intensity of inductive heating should not be underestimated when performing infrared inspections of electrical switchgear. Inductive heating is derived from the proximal interaction of non-current carrying devices with the magnetic field around energized conductors that are under load.
Inductive heating affects ferrous metals and causes inexplicable heating of non-current carrying components. The intensity of heating is a function of the amount of current passing through the conductor rather than the voltage class. In some cases, the affected components can reach temperatures in excess of several hundred degrees.
During a recent inspection at a power generation plant, two examples of inductive heating were observed near the plant’s step-up transformers. Images captured showed intense heating on a non-current carrying support pole and bus transition box, both of which were close to iso-phase bus entering a 13 kV to 230 kV step-up transformer. Temperatures documented on these devices were in excess of 400°F. Being the starting point of transmission service, a heavy current load would be expected on energized equipment.
Often, engineering designs on switchgear enclosures and other electrical equipment do not take into consideration the interaction of non-current carrying ferrous devices within electro-magnetic fields. In some cases, these situations can pose safety hazards when the affected component is in contact with combustible materials or heats structures that are accessible to human contact. When faced with perplexing heat patterns on components that should not be hot, inductive heating may be to blame.
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Thermal Imagery to Detect Roof Fasteners
Tip written by: Infraspection Institute
Thermal imaging is a proven technique for detecting latent moisture within low-slope roofing systems. Under the right conditions, thermal imaging may also indicate the number and location of roof fasteners.
Mechanical fasteners are a critical component in flat roofs. Essentially large sheet metal screws that are installed through large steel or plastic plates, mechanical fasteners secure sheets of insulation to the roof deck. In order to help ensure roof system performance, it is critical that each insulation board is installed with a sufficient number of fasteners.
An insufficient number of roof fasteners may be the result of improper design or a contractor attempting to cut corners on material. When fastener quantity is in doubt, a thermal imager may be used to indicate the number and location of fasteners. Typically, fasteners and plates will show as relatively warm components against a cooler background when imaged post-sunset after a sunny day. In the image below, subsurface fasteners and steel plates show as regularly-spaced warm circles.
When attempting to detect thermal patterns associated with mechanical fasteners, keep the following in mind:
- Thermal imaging should begin at or shortly after sunset
- Imagery associated with fasteners may only appear for a short time
- Fasteners may not be detectable on low emittance or gravel-surfaced roofs
Infrared inspections of flat roofs are one of the many applications covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. For course schedules or to obtain a copy of the Standard for Infrared Inspection of Insulated Roofs, visit Infraspection Institute online or call us at 609-239-4788.
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Determining Maximum Operating Temperature for Motors
Tip written by: Infraspection Institute
Operating temperature can have a significant impact on the service life of operating electric motors. Accurately determining maximum operating temperature for motors is critical for setting temperature limits.
One of the specifications for electric motors is maximum operating temperature. This temperature value is determined by several factors including, but not limited to, the motor’s insulation class. Exceeding the maximum temperature for a motor will shorten the life of the motor’s dielectric materials and will result in decreased service life for the motor.
In order to calculate a motor’s maximum rated temperature, one must know the motor’s ambient temperature rating and its rated temperature rise above ambient. Both of these values are generally found on the motor nameplate located on the exterior of the motor casing.
To calculate a motor’s maximum operating temperature, add the ambient and rated rise temperatures. Their sum is the maximum operating temperature for the subject motor at 100% load.
Example:
- Rated Ambient: 40 C
- Rated Rise: 90 C
- 40 + 90 = 130 C or 266 F
It is important to note that some motors specify insulation class rather than a numeric value for temperature rise. In such cases, it is necessary to know the operating limits for the insulation class of the subject motor.
The Infraspection Institute Standard for Infrared Inspections of Electrical Systems & Rotating Equipment provides temperature limits for several common insulation classes of AC and DC motors. In addition to providing inspection procedures, it also provides temperature limit data for lubricants, bearings and seals. To order a copy of the Standard, call 609-239-4788 or visit the Infraspection online store.
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Grilling Safety Tips
Tip provided by the National Fire Protection Association
With Summer upon us, many will return to outdoor cooking on a regular basis. In this Tip we offer important safety considerations for all outdoor chefs.
There’s nothing like outdoor grilling. It’s one of the most popular ways to cook food. But, a grill placed too close to anything that can burn is a fire hazard. They can be very hot, causing burn injuries. Follow these simple tips and you will be on the way to safe grilling.
- Propane and charcoal BBQ grills should only be used outdoors
- The grill should be placed well away from the home, deck railings and out from under eaves and overhanging branches
- Keep children and pets away from the grill area
- Keep your grill clean by removing grease or fat buildup from the grills and in trays below the grill
- Never leave your grill unattended
Charcoal grills
- There are several ways to get the charcoal ready to use. Charcoal chimney starters allow you to start the charcoal using newspaper as a fuel
- If you use a starter fluid, use only charcoal starter fluid. Never add charcoal fluid or any other flammable liquids to the fire
- Keep charcoal fluid out of the reach of children and away from heat sources
- There are also electric charcoal starters, which do not use fire. Be sure to use an extension cord for outdoor use
When you are finished grilling, let the coals completely cool before disposing of them in a metal container.
Propane grills
Check the gas tank hose for leaks before using it for the first time each year. Apply a light soap and water solution to the hose. A propane leak will release bubbles. If your grill has a gas leak, detectable by smell or the soapy bubble test, and there is no flame, turn off the gas tank and grill. If the leak stops, get the grill serviced by a professional before using it again. If the leak does not stop, call the fire department. If you smell gas while cooking, immediately get away from the grill and call the fire department. Do not move the grill.
If the flame goes out, turn the grill and gas off and wait at least 15 minutes before re-lighting it.
Download these NFPA safety tips on grilling
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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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June 8, 2020
Sponsored by: Keysight Technologies
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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June 15, 2020
Sponsored by: Keysight Technologies
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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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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Point Radiometers & Spot Measurement Size
Tip written by: Infraspection Institute
With awareness of infrared technology at an all time high, point radiometers have become a common tool in many areas. Frequently, knowledge of proper operation lags behind instrument popularity. Understanding how spot measurement size affects accuracy is imperative to collecting meaningful data.
All radiometers are limited by a characteristic known as spot measurement size or spot size, for short. Spot size is determined by a radiometer’s detector and optics. Typically, spot size increases as distance to the target is increased. For accurate temperature measurement, spot size must always be smaller than the target being measured. When using a point radiometer, be sure to keep the following in mind:
- Point radiometers are usually supplied with a Distance to Spot Ratio value. To determine spot size, divide distance to target by ratio value.
- Point radiometers have minimum focus distances. At lesser distances, spot size will not decrease.
- Single, laser-generated aiming dots do not represent spot size
- Multiple, laser-generated aiming circles/dots often understate spot size
- Beware of stated spot size ratio values. Spot size ratios are frequently quoted at 90% radiance (accuracy) or less
When using a point radiometer, be sure to understand the limits of your instrument and the challenges presented by your target. Always use correct emissivity values and stay within the limits of your instrument.
Spot measurement size and its effect on non-contact temperature measurement is just one of the many topics covered in all Infraspection Institute Level II Certified Infrared Thermographer® training courses. For more information on open enrollment classes or our Distance Learning opportunities, call 609-239-4788 or visit us online at www.infraspection.com.
