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 dry-type transformer, be certain to include not only the primary and secondary connections but also the following items as well:
1) Inspect neutral and grounding connections for hot spots.
2) Compare phase coils to each other. Transformers with balanced loads will exhibit similar temperatures between windings.
3) Compare each phase coil to itself. Properly operating coils should exhibit no pronounced hot or cold spots.
4) Inspect voltage tap jumper connections. Both connections should be the same temperature. In most cases, the jumper will be colder than the windings.
Thermogram reveals hot spot caused
by loose tap connection
5) Compare transformer operating temperature to nameplate rating. For long term service, transformers should not operate above their maximum rated temperature.
In conjunction with the infrared inspection, cooling fans should be checked for proper settings and operation.
Finally, transformers require proper air circulation for cooling. To help ensure maximum airflow, transformer ventilation openings should be unobstructed and free from dirt.
Infrared inspection of power distribution systems is one of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. For information on thermographer training including course locations and dates, visit us online at www.infraspection.com or call us at 609-239-4788.
Cold weather clothing is a matter of functionality not fashion. Clothing needs to be worn in layers in order to trap air which is warmed by the body. When selecting clothing, start with the innermost layer and work outward. The use of multiple layers will trap warm air while providing greater ease of movement. As you add layers, be sure to adjust the next layer’s size accordingly.
The first layer should be made of a synthetic material that will wick perspiration away from the body and maintain its insulating properties when damp. The second layer is your main insulator and should be a breathable material that maintains its insulating properties when wet. Synthetic fleeces or natural wool are good choices. The outermost layer should be breathable and both wind and water resistant.
Head and neck protection is a must since nearly 40% of body heat is lost here. Perspiration is the main enemy of feet. The best footwear will have sturdy outers, good treads and a removable felt liner. Buy extra liners and replace them every few hours. Liners can take a full day to fully dry out so buy enough to get through a typical workday.
Mittens are the warmest but present problems in grasping tools etc. I have found that a heavy duty welder’s glove with cotton or wool gloves lining them provide good warmth and mobility. Buy enough liners to get you through the day. One final note, the body needs fuel to produce heat. Your calorie needs increase in cold weather and require regular replenishment with good wholesome foods.
“Jack Frost nipping at your nose.” These lyrics from a popular Christmas carol evoke romantic visions of winter; however, frostbite and hypothermia are dangerous medical conditions that can present serious safety hazards.
For many, the dead of winter is upon us. Thermographers working outdoors in cold climates can face serious safety challenges due to frostbite and hypothermia. Knowing the symptoms of these conditions and proper treatment is imperative for worker safety.
Frostbite is a severe reaction to cold exposure that can permanently damage its victims. A loss of feeling and a white or pale appearance in fingers, toes, or nose and ear lobes are symptoms of frostbite.
Hypothermia is a condition brought on when the body temperature drops to less than 90 degrees Fahrenheit. Symptoms of hypothermia include uncontrollable shivering, slow speech, memory lapses, frequent stumbling, drowsiness, and exhaustion.
If frostbite or hypothermia is suspected, begin warming the person slowly and seek immediate medical assistance. Warm the person's trunk first. Use your own body heat to help. Arms and legs should be warmed last because stimulation of the limbs can drive cold blood toward the heart and lead to heart failure. If the person is wet, put them in dry clothing and wrap their entire body in a blanket.
Never give a frostbite or hypothermia victim beverages containing caffeine or alcohol. Caffeine, a stimulant, can cause the heart to beat faster and hasten the effects the cold has on the body. Alcohol, a depressant, can slow the heart and also hasten the ill effects of cold body temperatures.
When documenting an infrared inspection with no detectable exceptions, thermographers should be aware that there is a big difference between reporting “no problems” versus “negative findings”.
Infrared inspections may be performed for a wide variety of reasons including condition assessment, quality assurance and predictive maintenance. In its simplest form, thermography detects, displays and records thermal images and temperatures across the surface of an object. In many cases, thermal anomalies are indicative of deficiencies, changes, or undesirable conditions within the object or system being inspected. Typically, such conditions are reported with a thermal image and a description of the anomaly.
Upon completing infrared inspections during which no anomalies are detected, thermographers will frequently report that the subject system has “no problems”. From a liability standpoint, this can increase a thermographer’s risk since there may exist problems that are simply not detectable by thermography. Most importantly, a proclamation of “no problems” may leave an end user with a false sense of security regarding the condition or integrity of the subject system.
Since it is not possible for thermography to detect all potential problems within a given system or object, it is advisable for a thermographer to report “negative findings” when no anomalies are detected. This statement is direct, to the point, and in accordance with terminology utilized in other types of scientific testing.
Although the difference between “no problems” and “negative findings” may seem small, the proper use of terminology can help to prevent costly and embarrassing misunderstandings.
Temperature Differentials for
Infrared Building Inspections - Part 1
Tip written by: Infraspection Institute
A common question among thermographers is, “How much temperature differential is needed to obtain good data?” In this two-part Tip, we discuss required temperature differentials for infrared inspections of buildings.
Proper conduct of any infrared inspection requires that a detectable temperature differential or Delta T is associated with the sought-after defect at the time of inspection. For infrared inspections of buildings and their subsystems, the appropriate time for an infrared inspection will depend upon, but not be limited to: the type of condition or defect, time of day, local atmospheric conditions, and imaging vantage point.
For building energy loss inspections, published standards require an inside/outside temperature differential of 10 C or 18 F degrees for at least 3 hours prior to the inspection. Such a differential will help to ensure that there is adequate heat flow through structural components necessary for an accurate inspection. While it is possible to conduct energy loss inspections with a lesser inside/outside temperature differential, the likelihood of missing defects increases with a decrease in Delta T.
IR inspections to detect building energy loss may be conducted from either the interior or exterior of a building; however, imaging from the interior is often more comprehensive and useful than macro shots taken exclusively from the exterior. Regardless of vantage point, one must make certain to account for the effects of solar loading, especially when imaging during daytime hours. Thermal patterns associated with missing or damaged insulation may appear warm or cool depending upon vantage point and site conditions.
In addition to the above, detecting latent moisture within or evaporating from building materials assumes a relatively high target emittance. Low emittance surfaces associated with metal building facades or roofs coated with aluminum paint may not lend themselves to an accurate infrared inspection.
Lastly, all infrared data should be verified by independent means, as appropriate. This testing may include visual and/or invasive moisture meter readings.
Infrared inspection of buildings is 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.
Despite the important role they play in a commercial facility, electric motors tend to be both out-of-sight and out-of-mind until they fail. Infrared thermography can be used as a cost-effective diagnostic tool for detecting problems within electric motor systems.
Many infrared inspection programs include motor control circuits but overlook the motor itself. Evidence of several conditions which can lead to premature motor failure can be detected with a thermal imager. The following are suggestions for thermographically inspecting motors.
With cover removed, inspect electrical connections at the motor junction box. This should be done in conjunction with the regularly scheduled inspection of the facility’s electrical system.
Inspect motor casing for localized hotspots which may be indicative of short circuits within motor windings
Qualitatively compare individual motors to similar motors under similar load
When possible, qualitatively compare inboard and outboard bearings for each motor. If a large Delta T is present, it may be indicative of misalignment or a rotor balance problem. If both bearings are hot, the bearings may be worn or improperly lubricated.
Because no complicated analysis is required, infrared inspections typically can be performed rapidly and at a fraction of the cost of other types of motor testing. Additionally, infrared can detect evidence of misalignment at lower thresholds than those detectable by vibration analysis and motor current signature analysis.
Lastly, infrared inspections of motor bearings and stator should be performed monthly by experienced, certified infrared thermographers who thoroughly understand the theory and operation of electric motors.
“First impressions count.” This timeless observation underscores the importance of appearances when meeting someone for the first time. This same observation also holds true in the modern, wired world.
Experienced businesspeople know the importance of first impressions. To this end, they do their best to dress, act, and speak appropriately when meeting prospects. Why is it then that so many fail to understand that first impressions on the web are equally important?
The worldwide web and email have greatly expanded the reach of many businesses. No longer are businesses confined to geographic regions; their ability to reach a worldwide audience is limited only by the connectivity of their prospects.
Prospects will form opinions about businesses or individuals through their websites, emails and posts to public message boards. When using any of these resources, keep the following in mind:
Be courteous and respectful of others
Never post anything you should not say in public
Do not make personal attacks on individuals or companies
The internet crosses international and cultural boundaries. Depending on local customs, people do things differently. This does not make them wrong.
Remember, with every new encounter, others form impressions of you. Because first impressions can be permanent, make certain that your web impressions are always positive.
Infrared inspections can be especially helpful in formulating a roof maintenance program. As with other types of infrared inspections, several interdependent factors can affect a thermographer’s success. Before beginning an inspection, there are several things that one must consider to help ensure accurate data collection.
Roof Construction: Applicable roof construction is as follows: Built up or single-ply membrane installed over, and in continuous contact with, a layer of insulation or an insulating deck. Roof may be either smooth, granule, or gravel-surfaced. If gravel surfaced, stones should be pea sized or smaller.
Roofs covered with concrete pavers or river washed ballast (walnut sized rock) are not candidates for an accurate infrared inspection.
Roofs with thick insulation systems may be difficult to image when moisture is present only at the bottom of the insulation layer.
Equipment: For highly reflective and smooth-surfaced roofs, use a short wave (3-5 micron) imager to overcome reflections caused by nighttime sky. For gravel or granule surfaced roofs, one may use either a long wave or short wave camera with good results.
Time of Day: In general, infrared inspections are best performed at night after a sunny day; however, there are several environmental factors which will influence the ability to collect accurate data. Minimum weather requirements are as follows:
Recent rain sufficient to cause wetting of roof components
Dry roof surface at sunrise. No ice, snow or standing water
Mostly sunny day
Daytime highs above 40°F
Daytime winds of less than 15 mph at the rooftop
Nightime winds of less than 15 mph at the rooftop during IR inspection
No rain on day of infrared inspection
Roofing Materials: Some materials are more difficult to inspect than others. Roofs having lightweight concrete or gypsum can be more difficult to inspect because they can retain significant quantities of moisture either left over from construction or due to building usage.
For roofs having an insulation layer, the absorbency of roof insulation can also affect one's ability to detect moisture as well as the intensity and type of thermal patterns observed.
Water Ingress: Not all water that enters a roofing system will enter the insulation system. Infrared inspections rely on moisture being absorbed by roofing system components causing a change in thermal capacity or thermal conductivity. Should water bypass the roof insulation, no unusual thermal patterns will be observed.
Moisture Content: The amount of moisture within the roofing system will have a direct impact on the images observed. The clear, well-defined IR images found in text books are not always found in the field.
Additionally, roofs which are completely saturated will not exhibit clear thermal patterns but will often exhibit a mottled thermal pattern.
Moisture Verification: To ensure accuracy all infrared data must be verified through invasive testing and the results correlated with infrared data. Remember, an infrared imager is not a moisture meter.
Experience: Because thermography is an art as well as a science, an experienced operator may be able to shed some expertise on difficult roofs. This is a situation where working with a mentor can be especially helpful or you may wish to work with an experienced infrared consultant who specializes in roof inspections.
“Watch Your Step”. Sage advice that we’ve heard a million times; however, falls continue to be one of the most common workplace accidents. Following a few simple steps can help thermographers to prevent most falls.
Each year falls in the workplace account for over one million injuries and several hundred fatalities. Even a simple slip can cause serious injuries. Many falls can be prevented by following some basic rules:
Identify all potential tripping and fall hazards before work starts
Look for fall hazards such as unprotected floor openings/edges, shafts, skylights, stairwells, and roof openings/edges
Use appropriate fall protection equipment; inspect equipment for defects prior to each use
Never use boxes or chairs in place of an appropriate ladder or stepstool
Secure and stabilize ladders before climbing them; never stand on top rung or step of a ladder
Use handrails when going up/down stairs
Practice good housekeeping - Keep floors dry and free of clutter such as cords, hoses , and cables
Keep walkways free of snow and ice
Lastly, be sure to use sturdy footwear appropriate to the task. Work boots and shoes should be laced and tied to prevent tripping and to afford proper support. When it comes to fall protection, an ounce of prevention is worth a pound of cure. For more information on workplace safety standards and fall protection, visit www.osha.gov.
When performing infrared temperature
measurements, reflected infrared energy can be
a significant error source. This potential error
source can be overcome by using the proper radiometer
and test procedure.
All thermographers have experienced
reflected energy when inspecting low emittance
targets. For qualitative imaging, single-point
reflections may be avoided by changing viewing
With quantitative imaging, failing
to compensate for reflected energy can account
for significant measurement errors. The infrared
energy received by a radiometer is the sum of
emitted, reflected and transmitted energy (E+R+T=1.0).
For targets with a transmittance of zero, the
error sources are emittance and reflectance.
Using a quality radiometer, reflected energy
can be measured and compensated for by using
the Reflector Method described below.
1. Set radiometer Emittance
control to 1.00
2. Locate radiometer at desired distance from target to be measured
3. Aim and focus imager
4. Position diffuse reflector in front of, and parallel to, face of
5. Measure apparent temperature of reflector surface and remove reflector
6. Enter value obtained in Step 5 into radiometer’s computer
under reflectance input – commonly labelled Background, TAmbient,
or Reflected Temperature.
Lastly, be sure to maintain a safe working distance from any energized or potentially dangerous targets.
UPS systems and emergency generators
are common defenses for facilities where uninterrupted
electrical power is critical. Performed properly,
IR inspections can help to improve reliability
of emergency power systems.
Most facilities perform IR inspections
of their electrical distribution systems at least
annually as part of a PM program. To help ensure
maximum reliability, regularly-scheduled IR inspections
should also include the emergency power systems
as well. When performing infrared inspections
of emergency systems be sure to:
Inspect all backup generators
while running. Begin inspection at generator
output leads and proceed to generator bus,
breakers, and switchgear.
Include all Automatic and
Manual Transfer Switches. Inspect switches
in both normal and emergency positions.
Inspect UPS system controls,
switchgear, battery cells, battery bus and
wiring. Battery cell temperatures should be
the same between cells with no hotspots on
Have adequate load on the
subject emergency circuits This may be accomplished
with normal facility load or by utilizing a
Taking the time to properly
include your emergency power equipment in your
IR inspection program can pay huge dividends
by increasing the likelihood that your backup
equipment won’t leave you in the dark
should the power fail.
A specification commonly
provided for thermal imagers is Instantaneous Field of View
or IFOV. Many people mistakenly believe that IFOV values provide
meaningful information about a thermal imager’s performance.
Unfortunately, this is simply not true.
Originally developed for evaluating the
optical performance of thermal imaging systems, IFOV values
were intended to allow a user to calculate the minimum target
size needed to achieve 50% probability of detection at any
given distance. Using IFOV values to evaluate modern thermal
imagers and radiometers is unreliable for several reasons:
o To date, there is no accepted standard
for determining IFOV. Consequently, imager manufacturers
calculate IFOV values differently, making test results impossible
o Because IFOV values are reported for
a single pixel, they cannot be used to accurately calculate
spot measurement size for imaging radiometers since accurate
temperature measurement requires several pixels, not just
o Stated IFOV values are traditionally
reported at 50% radiance or less which is unreliable for
both temperature measurement and accurate thermal imaging.
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.
Thermographers often work
in environments that require the use of respiratory protection.
In this Tip we discuss the selection and use of common respirator
A respirator is a device designed to
protect the wearer from inhaling harmful dusts, fumes, vapors,
or gases. There are several types of respirators, each having
a different intended application. Several types are listed
below along with their applications.
dust masks are usually not NIOSH-approved.
They must not be used to protect from hazardous atmospheres.
However, they may be useful in providing comfort from
pollen or other allergens.
filtering face pieces (dust masks) can be used
for dust, mists, welding fumes, etc. They do not provide
protection from gases or vapors. DO NOT USE FOR ASBESTOS
OR LEAD; instead, select from the respirators below.
respirators can be used for protection against
most vapors, acid gases, dust or welding fumes. Cartridges/filters
must match contaminant(s) and be changed periodically.
respirators are more protective than half-face
respirators. They can also be used for protection against
most vapors, acid gases, dust or welding fumes. The face-shield
protects face and eyes from irritants and contaminants.
Cartridges/filters must match contaminant(s) and be changed
powered-air-purifying respirators (PAPR) offer
breathing comfort from a battery-powered fan which pulls
air through filters and circulates air throughout helmet/hood.
They can be worn by most workers who have beards. Cartridges/filters
must match contaminant(s) and be changed periodically.
Self-Contained Breathing Apparatus (SCBA) is
used for entry and escape from atmospheres that are considered
immediately dangerous to life and health (IDLH) or oxygen
deficient. They use their own air tank.
Respiratory protection must be worn whenever
you are working in a hazardous atmosphere. The appropriate
respirator will depend on the contaminant(s) to which you
are exposed and the protection factor (PF) required. Required
respirators must be NIOSH-approved and medical evaluation
and training must be provided before use.
Thermographer safety is one of the many
topics covered in the Infraspection Institute Level I Certified
Infrared Thermographer® training course. For more information
or to register for a course, visit Infraspection
Institute or call us at 609-239-4788.
For more complete information on workplace
safety, visit the OSHA
Robert J. Incollingo
416 Black Horse Pike
Glendora, NJ 08029
Thermographers (like lawyers) are subject to the "call girl principle," which states that the perceived value of a service drops like a stone once the service has been performed. To boost your prospects of getting paid, above all you need to get your bills out promptly, and aggressively follow up on any delay in payment. Here are five other steps you can take to increase your chances of getting paid:
1. Acquire and use a graduated set of collection letters for your delinquent accounts. Sample collection letters are readily and freely available on the internet, starting with a gentle reminder and increasing in impatience until the matter must be referred out to an attorney. Copy your lawyer with your final collection letter. Many times, a cc: line on the bottom of the letter is all it takes to convince your debtor that he’s had his last warning. Don’t forget to actually send the copy.
2. Early on, a telephone call should be made to catch any mistakes in the system, such as wrong addresses or accounting, and to find out if there is an acceptable reason for the delay in payment. Most people pay their debts unless something prevents them. You may be willing to accommodate their problem for a defined period.
3. Don’t forget to provide in your contract or purchase order for the recovery of attorneys’ fees in the event you have to sue. Most times, the thought of picking up the other side’s legal bills is enough to prevent delinquency all by itself. Remember, however, that unless the customer signs the contract, the attorneys’ fees clause will probably be worthless.
4. Keep copies of the checks you receive. In the event you need to sue to collect on a debt, the information found on a check will help you quickly locate and levy on the account. A bank levy is the easiest way to get real dollars to satisfy your judgment.
5. Discount your expectations. Collection agencies and attorneys don’t work for free, so compromise may be your best course. Figure on backing down to a sum which approximates your likeliest recovery less the expected costs to get there. When you’ve settled on a number you won’t walk away from, remember that terms of payment on time are still negotiable. That's why they call them lump sums - installments are just easier to swallow.
Bob Incollingo is an attorney in private practice in New Jersey and a regular speaker at Infraspection Institute’s annual IR/INFO Conference.
Recent advancements in technology are reshaping 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.
Thermal anomalies are not
always as obvious as one might expect. Often, subtle thermal
differences can be indicative of major problems. Because infrared
thermography is a visual inspection technique, its effectiveness
relies on the observation skills of the thermographer. Like
any visual inspection technique, a thermographer must actively
concentrate on the imagery displayed by their thermal imager.
Contrary to popular belief, humans are not
inherently effective observers. Because humans tend to be
casual in their observations, they frequently overlook subtleties.
Whenever imaging, a thermographer’s eyes should always
visually scan the monitor left to right and up and down while
asking him/herself the following three questions:
1. What am I seeing
2. Why am I seeing this
3. Is this normal/reportable
While this approach may sound cumbersome
at first, this practice will soon become instinctive and can
help prevent you from overlooking the subtle thermal patterns
that can be indicative of serious problems.
First impressions not only count but they can last a long time. Bad impressions can last forever especially if their source is constantly in public view on an internet message board.
Humans leave their mark everywhere they go. They leave fingerprints on the things they touch, footprints in the sand where they walk, and personal impressions on those they meet. A less considered type of impression is an ‘internet footprint’ which is created whenever a person posts to public message boards or blogs.
Web posts often make permanent impressions on those who read them. Web posts that are timely, accurate, and professional can serve to help others and create a positive image for their authors. Bad or inappropriate posts can cause permanent damage and even harm one’s business. When posting on the net, following a few simple rules or netiquette can help to avoid creating a bad impression in cyberspace.
Do not post anything you would not (or should not) say in public
Always refrain from using foul, profane, or vulgar language
Do not badger others or attack their personal beliefs
Avoid over exposure. Chronic posting or posting ‘round the clock gives the impression that you have nothing better to do.
Keep in mind that posts can be viewed worldwide across different languages and cultures. Humor and witticism rarely translate well; sarcasm is often magnified.
Lastly, remember to think before you hit the ‘send’ button. Web posts often have an unintended permanence and are available for the world to see. Webmasters are rarely under any obligation to remove or edit posts regardless of how unflattering they may be.
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.
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 radiometer¹s 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.
Savvy business owners are
always on the lookout for new business opportunities. Thermography
can be a particularly good fit for building and home inspectors
seeking to expand their services and generate new revenue.
The past few years have seen tremendous growth
in the use of thermography for building inspections. Greater
public awareness and lower equipment costs have induced many
home and building inspectors, damage restoration specialists
and pest management professionals to add thermography to their
The income potential for thermographers is
significant. Depending upon services offered and rate structure,
a single thermographer is capable of generating $250,000 per
year in revenue. This potential can be influenced by a number
of factors including one’s choice of infrared imaging
equipment. Prior to purchasing equipment, one should keep
the following in mind:
• Determine your firm’s capabilities
with respect to expertise and manpower.
• Conduct a marketing study to determine
what services you will offer. In particular, look for services
that will repeat annually and/or provide the greatest revenue
with the least amount of sales effort.
• Entry level equipment can limit
one’s capabilities and revenue potential. Try to anticipate
your equipment needs for at least three years and purchase
Despite claims to the contrary, thermography
is not a ‘point and shoot’ technology. In addition
to thorough knowledge of the systems or structures being inspected,
thermographers should be trained in infrared theory, heat
transfer concepts, equipment operation and selection, current
industry standards, and report generation. For those lacking
experience, training should be completed prior to purchasing
Infrared inspection of buildings and
their subsystems 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.
Thermography is a versatile
nondestructive test technique that has a wide
variety of applications. In short, thermography
can be applied to any situation where knowledge
of heat patterns and associated temperatures
across a surface will provide meaningful data
about a system, object, or process.
In thermography, there are two
basic approaches to evaluating data. Qualitative
thermography or thermal imaging relies on observing
thermal patterns and noting any inexplicable
differences or anomalies. Quantitative thermography
adds non-contact temperature measurements to
Many systems produce heat as
a byproduct of operation. Such systems include
electrical distribution systems, machinery and
insulated structures. These systems are generally
inspected during normal operation once line-of-sight
access is obtained.
Thermography can also be applied
to systems that do not produce heat as a byproduct
of operations by actively heating and/or cooling
the target and observing the resulting images.
Systems that are candidates for active thermography
include building facades, low slope roofing systems,
storage tanks and composite materials.
When heated or cooled
properly, thermal patterns caused by changes
in the thermal conductivity or capacitance
of the subject system can provide evidence
of internal structures, water infiltration,
or contaminants. The use of active thermography
is growing, especially for inspection of composite
materials used in the aircraft, aerospace,
and marine industries.
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.
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.
1. Calibrated imaging radiometer with a computer that allows thermographer to input Reflected Temperature and Emittance values
2. Natural or induced means of heating/cooling target to a stable temperature at least 10ºC above/below ambient temperature
3. Calibrated contact thermometer
1. 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
2. Measure and compensate for Reflected Temperature
3. Place imager crosshairs on target
4. Use contact thermometer to measure target temperature at location of imager crosshairs. Remove contact thermometer
5. 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.
one of the most spectacular natural phenomena. For thermographers
who work outdoors, it can present a serious safety hazard.
This week’s Tip discusses how you can protect yourself
from this serious safety hazard.
Each year, lightning kills an average of
67 people in the United States; hundreds more are injured.
Few people really understand the dangers of lightning. Many
fail to act promptly to protect their lives and property don't
understand the dangers associated with thunderstorms and lightning.
Thunderstorms are most likely to develop
on warm summer days and go through various stages of growth,
development and dissipation. On a sunny day, as the sun heats
the air, pockets of warmer air start to rise in the atmosphere.
When this air reaches a certain level in the atmosphere, cumulus
clouds start to form. Continued heating can cause these clouds
to grow vertically upward in the atmosphere into "towering
cumulus" clouds. These towering cumulus may be one of
the first indications of a developing thunderstorm.
During a thunderstorm, each flash of cloud-to-ground
lightning is a potential killer. The determining factor on
whether a particular flash could be deadly depends on whether
a person is in the path of the lightning discharge. In addition
to the visible flash that travels through the air, the current
associated with the lightning discharge travels along the
ground. Although some victims are struck directly by the main
lightning stroke, many victims are struck as the current moves
in and along the ground.
Lightning can strike as far as 10 miles away
from the rain area in a thunderstorm. That's about the distance
you can hear thunder. When a storm is 10 miles away, it may
even be difficult to tell a storm is coming.
IF YOU CAN HEAR THUNDER, YOU ARE
WITHIN STRIKING DISTANCE. SEEK SAFE SHELTER IMMEDIATELY!
The first stroke of lightning is just as
deadly as the last. If the sky looks threatening, take shelter
before hearing thunder. Once indoors, stay away from windows
and doors and avoid contact with anything that conducts electricity.
Wait at least 30 minutes after the last clap of thunder before
Infrared inspections of electrical distribution systems frequently include motor controllers. Proper imager settings and inspection technique are imperative In order to accurately inspect these critical electrical devices.
Industrial motors of all sizes are frequently controlled by remote devices known as motor controllers. Motor controllers are small to large metal-clad devices containing one or more large solenoids that provide manual or automatic control of motor functions including: starting/stopping, motor speed, torque, and rotation direction. Motor controllers may be installed as individual units or grouped with others in motor control centers.
Motor controllers often contain a number of electrical devices operating at widely differing temperatures. These devices include control circuits, transformers, fuses, circuit breakers, contactors, thermal overloads, and circuit conductors. The temperature of these devices can range over hundreds of degrees.
When performing an infrared inspection, setting a thermal imager’s controls to encompass the whole motor control in a single view is not recommended as significant problems can be overlooked. For best results, we recommend the following:
Ensure that subject motor controller is under load
Image from a distance that permits viewing only of the subject controller components.
Perform inspection in direction of line to load side of motor control circuit
View subject components individually
Adjust level/gain settings to optimize image for each component inspected
Compare features of similar components to each other, noting inexplicable differences
For controllers with multiple contactors, it will be necessary to inspect each contactor individually while under load. Be sure to allow sufficient time for subject contactor to achieve running temperature. 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 us online at www.infraspection.com or call us at 609-239-4788.