Infrared Prior to PM Shutdowns
Many facilities undergo regularly scheduled shutdowns for preventive maintenance. Performed prior to shutdowns, infrared inspections can help to point out potential problems in electrical and mechanical systems and allow for more effective use of resources during a shutdown.
When planning a scheduled outage, it is a good practice to perform infrared inspections four to six weeks prior to the outage. Doing so can uncover hidden problems and allow for scheduling of additional requisite manpower and/or obtaining replacement parts prior to the shutdown. Infrared inspections can also save money by helping to direct maintenance efforts where they will be most needed during the planned outage.
Pre-outage infrared inspections should be performed with subject equipment energized and operating under normal load. Inspections should be performed by trained and certified thermographers who are familiar with the equipment being inspected. A follow-up infrared inspection of all repaired/retrofitted equipment should then be performed within 48 hours of repair or installation to confirm that repairs were effective.
For more information on thermographer training and certification, or to obtain a copy of the Standard for Infrared Inspection of Electrical Systems and Rotating Equipment, please contact Infraspection Institute at 609-239-4788 or visit us online at www.infraspection.com.
Winter Driving Tips
Tip written by: Infraspection Institute
With an unusually harsh winter well underway, many have already experienced driving challenges associated with severe weather. With this Tip, we offer some advice for driving in winter conditions.
Prepare Your Vehicle
- Make sure brakes, windshield wipers, defroster, heater and exhaust system are in top condition
- Check radiator for coolant level and adequate antifreeze protection. Fill windshield washer reservoir with freeze-resistant fluid
- Check tires for proper inflation and tread condition
- Carry an ice scraper, brush, and a shovel
- Maintain a full gas tank in case of traffic delays or should you need to turn back due to conditions
- Keep snow chains handy and in good condition
- Allow enough time. Trips take longer during stormy/icy conditions
- Keep windshield and windows clear
- Maintain a safe distance from other vehicles; snow and ice make stopping distances much longer
- Remember to avoid sudden stops and quick direction changes
- Watch for slippery spots. Bridge decks and shady spots can be icy when other areas are not
- Be more observant. Visibility is often limited in winter by weather conditions. Slow down and watch out for stopped vehicles and emergency equipment
Lastly, be certain to wear your seat belt. Consult your local weather forecast before you set out and consider postponing your trip if extreme weather is predicted.
Keeping Track of Your Lenses
If you have multiple imaging radiometers of the same make and model, it is imperative to keep your lenses with the imager chassis to which they have been calibrated. Because each lens is individually calibrated to a specific imager, mixing up lenses from different imager bodies can cause serious inaccuracies when measuring temperatures.
The easiest way to keep track of your lenses is to mark each lens with the serial number of the chassis to which it has been calibrated. This can be done by using a permanent marker or pressure sensitive label to apply the serial number to the body of individual lenses.
It is recommended that lenses be marked upon receipt of the camera. Taking a few minutes to do this before you use your new equipment can prevent errors and embarassment in the future.
Imager selection and operation are two of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. 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.
Setting Temperature Limits
Over the past thirty years, a number of temperature severity guidelines have been published by various organizations. When using these guidelines, you may compare similar components under similar load to each other OR compare the subject component to ambient. The former of these approaches is recommended since ambient temperature can swing widely over time. Furthermore, it is often impossible to obtain an accurate ambient temperature for devices located within an enclosure once the enclosure has been opened for the infrared inspection.
One of the most conservative temperature guides can be found in the Standard for Maintenance Testing Specifications, published by the InterNational Electrical Testing Association, Portage, Michigan. According to the NETA MTS, temperature differentials greater than 15° C are categorized as, “Major discrepancy; repair immediately”.
Other organizations publish less conservative temperature guidelines than the NETA MTS. Some guides require delta T’s of 70°C or higher to qualify as items of immediate concern. When setting temperature limits, one should remember that temperature differentials cannot be utilized to predict time to failure for an electrical device. Therefore, all thermal anomalies detected during an infrared inspection should be investigated and proper corrective measures undertaken as soon as possible.
Setting temperature limits and prioritizing exceptions for electrical and mechanical equipment are two of the many topics covered in the Level II Infraspection Institute Certified Infrared Thermographer® training course. For information on thermographer training or to obtain a copy of the Standard for Infrared Inspection of Electrical Systems & Rotating Equipment, visit us online at www.infraspection.com or call us at 609-239-4788.
Know Your Safety Requirements
When working in a new facility or plant area for the first time, you may encounter safety rules that are new or different. It is always a good idea to review safety requirements with the project manager prior to project start to ensure that you are prepared.
When contacting a project representative concerning safety, be sure to ask the following:
- What general safety training and/or site specific training is required?
- Is special clothing, shoes or other Personal Protective Equipment required?
- Can infrared and related test equipment be used in the subject areas?
- Are respirators or additional safety equipment/monitors required?
- Will the work involve hazardous locations such as confined spaces, scaffolding or elevated platforms?
- What medical conditions might preclude a person from working in the subject area(s)?
- Are there site specific emergency procedures including evacuation, designated rally spots and how to report an incident?
Once the project commences, be sure to maintain good situational awareness and always stay with your qualified assistant. Becoming familiar with area safety rules in advance of a project can help to avoid cancelled projects and embarrassment while helping to maximize safety.
Thermographer safety and the selection of safe work practices are two of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. 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.
Infrared Equipment – New or Used?
Purchasing a pre-owned thermal imager can result in significant savings over the cost of a new unit. Prices for new thermal imagers can range from under $1000 to tens of thousands depending upon features and capabilities.
With the recent introduction of several new models of thermal imagers, there are several used pieces of equipment available from private sellers and manufacturers who have taken used equipment as trade-ins. Buying an imager from a private seller can be risky as no warranty is offered and you may not know how the equipment has been handled.
Purchasers of used equipment should be aware that there are no third party repair facilities for any infrared test equipment. Consequently, all equipment must be serviced by the company that manufactured the subject equipment. Furthermore, some thermal imagers are no longer being supported or serviced by the companies who manufactured them. Purchasing used equipment from a manufacturer is generally less risky as many manufacturers do offer limited warranties and service for used equipment that they sell. Significant savings can often be realized by purchasing sales demo units that usually become available once a manufacturer introduces a new model imager.
In order to avoid a costly error, buyers should complete a formal thermography training course BEFORE they buy any equipment. Doing so will enable one to better acquaint himself with the different types of cameras available, the applications and limitations of same, and how to accurately use this equipment in the field. Lastly, the greatest limiting factor in an infrared inspection is the equipment operator. Relying on data obtained by untrained persons can have disastrous consequences. To this end, a trained and certified operator of infrared equipment is of paramount importance for accurate data collection and interpretation.
Imager selection and operation are two 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.
Wide Angle Lenses
Using a standard lens to perform infrared inspections at close distances can be particularly difficult. This situation is quite common when inspecting motor control centers and some types of mechanical equipment.
If you must image from a near distance, you may not be able to compare your target to an adjacent reference. For larger targets you may be able to image only a portion of the target.
Wide angle lenses increase an imagers visual field of view allowing a thermographer to image a wider target area without having to move farther from the target. Wide angle lenses are available for most imagers in multipliers of either 2x wide or 3x wide. Spot measurement size will increase proportionately to the width multiplier for the lens.
If you are taking temperatures, be sure that your wide angle lens has been calibrated for your imager.
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.
Combining IR & Ultrasound for Steam Trap Testing
In order to increase the accuracy of thermographic inspections of steam traps, contact ultrasonic testing should be used as well as infrared imaging. Contact ultrasonics are much more sensitive to trap failures than temperature measurement alone.
Over time, two different non-destructive technologies have been employed to test steam systems – contact ultrasonics and temperature measurement. Used individually, each of these techniques has limitations that can lead to false positive and/or false negative results. Combining temperature measurement with ultrasound can result in a highly accurate test method by following a few simple steps:
- Measure trap inlet to ensure that temperature is above 212º F. If trap inlet is below 212º F, ascertain why steam is not reaching trap
- Listen to the trap outlet with contact probe of ultrasonic unit. Continuous hissing or rushing sounds usually indicate a failed trap
- Ascertain that trap is cycling periodically. Frequent cycling may be caused by an undersized or worn trap
- Tag defective traps and document in a written report
- Re-test defective traps after repair to ensure the effectiveness of repairs
While it takes some practice to become proficient with ultrasonic testing, the increased accuracy is worth the effort. Lastly, always be sure to follow appropriate safety precautions especially when working with high pressure steam or when using ladders or lift equipment.
Infrared inspection of steam traps is one of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. For information on thermographer training including course locations and dates, visit us online at www.infraspection.com or call us at 609-239-4788.
The Tortoise and the Hare
Everyone has heard the fabled race between the tortoise and the hare in which the tortoise beats the hare. One of the morals of the story is that a steady pace may be more fruitful than erratic bursts of speed.
Thermographers who perform infrared inspections should keep in mind that a slow and steady pace can lead to victory. Working at an even pace can help to prevent overlooking the subtle temperature variations that often indicate serious problems. Purchasers of thermographic services should bear in mind that the best value is not in the fastest inspection time, but rather in the thoroughness and accuracy of the inspection.
When it comes to your next infrared inspection, beware of the hare. Inspections that are praised more for their swiftness today may be cursed in the future for their costly oversights.
Properly conducting an infrared inspection is one of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. For course locations and dates or information on our Distance Learning courses, visit us online at: www.infraspection.com or call us at 609-239-4788.
Setting Up Inspection Routes
Proper planning prevents poor performance. This frequently repeated phrase has been applied to many disciplines and has application in thermography as well. One of the greatest appeals to thermography as a PdM tool is the wide range of potential applications. However, without planning the varied uses for thermography can cause one to lose focus and compromise program efficiency.
Using preplanned routes can improve inspection efficiency by serving as a roadmap for your inspection activities. When setting up inspection routes, keep the following in mind:
1. When possible, use established routes from other PdM technologies such as vibration analysis.
2. Routes should be of same class or hierarchy for subject equipment. As an alternative, establish routes based upon physical location.
3. Keep in mind requisite travel times between locations.
4. Establish routes to ensure that subject equipment will be under proper load.
5. Never include more equipment in a route than can be accomplished in a single work shift.
When following a route during an inspection, any equipment not inspected should be noted in the final project report.
Properly conducting an infrared inspection is one of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. For course locations and dates or information on our Distance Learning courses, visit us online at www.infraspection.com or call us at 609-239-4788.
Do You Have the Correct Time?
Tip written by: Infraspection Institute
Most modern thermal imagers have the ability to record time and date along with thermal images. Taking a moment to ensure that the correct time and date are displayed on your imager before you begin your inspection can help to avoid wasted time and the collection of inaccurate data.
Having the correct time associated with your imagery is important for several reasons. With correctly dated imagery, it is possible to:
- Accurately document when the inspection was performed
- Easily store and uniquely reference image files
- Record the duration of a thermal event
It is always good practice to consciously check your imager’s clock each time you start your imager and make any necessary adjustments. Be certain to check your clock periodically during your inspection and whenever you restart your imager such as after a battery change or power interruption.
If your imager frequently displays incorrect time, it may be indicative of a defective or dead internal battery. To help avoid this problem, arrange for replacement of internal clock batteries whenever you have your imager serviced or repaired.
Infrared imager operation and use are two of the many topics covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. For more information or to register for a course visit us online at www.infraspection.com or call us at 609-239-4788.
Modifying a Surface for Infrared Temperature Measurement
Unknown emittance values are often the greatest error source when taking infrared temperature measurements. This error source can be eliminated by modifying a target with a material having a known E value.
Some of the modifying materials that thermographers commonly use include flat-finish spray paint, PVC electrical tape, masking tape, and spray deodorants containing powder.
Prior to modifying any surface:
- Make sure that it is safe to contact the subject equipment.
- Obtain permission to modify the surface from the end user.
- Ascertain that the selected modifying material will not melt, catch fire or emit toxic fumes when heated.
Once you have determined it is safe to modify a surface, proceed as follows:
1. Place radiometer at desired location and distance from target. Aim and focus.
2. Measure and compensate for Reflected Temperature.
3. Apply a surface modifying material having a known E value on target making certain that material is in full contact with target and there are no air pockets. Modifying material should be larger than radiometer’s spot measurement size for the chosen distance from the target.
4. Enter E value of modifying material into radiometer’s E setting.
5. Measure temperature of modifying material once it has reached thermal equilibrium with target.
6. For greater accuracy, repeat measurement three times and average the results.
Accurate temperature measurement is one of the many topics taught in all Infraspection Institute Level II training courses. For information on course locations and dates or our Distance Learning program, please call us at 609-239-4788 or visit us online at infraspection.com.
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 can 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.
Know Your Target
When performing an infrared inspection, obtaining quality data relies on the use of proper equipment, thermographer training and knowledge of the system being inspected. It is imperative that a thermographer be familiar with the construction and operation of the object(s) to be imaged before the inspection begins.
Prior to performing an infrared inspection of an object for the first time, a thermographer should:
1. Become familiar with system construction by reviewing appropriate drawings or blueprints noting insulation materials located on, or within, the subject system and how they might impact findings.
2. Discuss with the end user the reason(s) for conducting the infrared inspection.
3. Review any previous inspection reports and operational data to determine history of the subject system including past problems.
4. Ascertain that the system is under normal operating conditions and how its operation is likely to affect thermal signatures.
5. Ensure that line-of-sight access is available and that environmental conditions and infrared equipment are appropriate for collecting accurate data.
6. Determine if a similar system is available for reference purposes.
Following the above can vastly improve the quality of collected data and help to reduce errors in reporting. As always, remember to work safely.
The subject of how to properly conduct an infrared inspection is one of the many topics covered in all Infraspection Institute Level I Certified Infrared Thermographer® training courses. For course locations and dates or to learn more about our Distance Learning Courses, visit us online or call us at 609-239-4788.
Cleaning IR Lenses
Always be sure to follow manufacturers instructions when cleaning infrared lenses and optics.
Lenses and optics are an integral part of any infrared imaging system. Most infrared optics are coated with special anti-reflective coatings to maximize the transmission of infrared energy to the system’s infrared detector. For imaging radiometers, each lens is individually calibrated to the imager.
Improperly cleaning a lens or coated optical element can cause the anti-reflective coating to be damaged thereby changing the transmittance of the lens and the measurement accuracy of the system. If the coating is sufficiently damaged, a costly lens replacement and system recalibration may be required. This recalibration would require sending your imager back to the manufacturer incurring up to several weeks of downtime for your imager.
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.
IR Inspections of Electrical Bus Ducts
Electrical bus ducts are a common feature found in many commercial and industrial electrical systems. When used to supplement regular PM, infrared inspections can help to detect loose or deteriorated connections that can lead to costly catastrophic failures.
Electrical bus ducts are used to distribute low voltage power throughout many industrial facilities. Modern bus ducts are unitized structures that contain insulated conductors within a steel casing. Individual sections of bus duct, each typically 10 feet long, are joined with bolted connections at the end of each bus section. Published industry standards recommend that bus duct connections be manually tightened every six months.
Even with regular tightening of bus duct connections, loose/deteriorated connections are difficult to detect. With the bus duct under load, a thermal imager can readily detect the temperature differentials associated with loose connections. Properly functioning bus ducts should exhibit no temperature differential in the vicinity of bolted connections. Because bus duct conductors are hidden from direct line of sight, any inexplicable temperature differentials should be investigated and corrected immediately. Disconnect switches and cable connections should be checked for thermal anomalies as well.
To ensure complete coverage, bus duct should be inspected from both sides of the duct along its entire length. Termination cabinets should also be inspected once the covers have been removed. Annual or semi annual infrared inspections performed by certified, experienced thermographers should be used to supplement regular bus duct maintenance.
Infrared inspection of bus ducts and electrical distribution systems are two 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.
Watch Your Step
“Watch Your Step” is a safety slogan we’ve all seen countless times. All too frequently, thermographers suffer injuries when engrossed in an inspection or disoriented by the display monitor of an infrared imager.
Thermography is a visual inspection technique that requires a thermographer to pay close attention to an imager’s monitor screen. Due to their construction, some portable thermal imagers can present safety hazards by partially obstructing a thermographer’s vision. Other thermal imagers may cause a thermographer to loose his/her balance due to the different perspective of the images they display.
In addition to hazards presented by imaging equipment, thermographers engrossed in an inspection can easily lose touch with their physical surroundings. To help prevent accidents, keep the following in mind:
- Always maintain adequate situational awareness of your surroundings
- Prior to imaging, survey the worksite for any tripping or fall hazards
- Be sure of your footing and overhead hazards at all times
- Stay with your qualified assistant at all times
Lastly, be extra careful when working in low light conditions. Watching a monitor screen in low light can impair your night vision for up to several minutes after you have viewed the screen. Taking the time to watch your step when imaging can help to prevent personal injury and avoid damage to your equipment or a client’s facility.
Thermographer safety is one of the many topics covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. For more information on class locations or our Distance Learning program, visit www.infraspection.com or call 609-239-4788.
IR Inspections of CMU Walls
Concrete Masonry Unit (CMU) walls are a common construction detail frequently used in single –story and low rise commercial block wall construction. An infrared imager can be used to quickly perform quality assurance inspections of reinforcing grout details which are critical to the strength of finished CMU walls.
During the construction of CMU walls, concrete grout is used to fill the cavity spaces of the blocks in order to provide structural integrity. Vertical details extending from the foundation to the top of the wall are usually placed at regularly spaced intervals along the length of the wall. Reinforcing grout is also placed around openings for doors and windows or in areas where extra wall strength is required.
Because grout details change the thermal capacitance and conductance of the wall, temperature differentials will occur wherever grout details are present. Infrared inspections may be performed under solar loading, heat loss, or cooling conditions depending upon local climate and time of day. Properly installed grout details will appear as uniformly cool or warm unbroken lines in the subject wall areas according to time of day and whether the inspection is performed from the interior or exterior of the building.
Infrared inspection of CMU walls is one of the many topics covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. For more information on class locations or our Distance Learning program, visit www.infraspection.com or call 609-239-4788.
Tip written by: Infraspection Institute
Lightning is 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 who 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 warm 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 clouds 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 leaving shelter.
For more info on lightning safety, visit: www.lightningsafety.noaa.gov
Infrared Inspections to Detect Latent Moisture
As interest in building remediation has increased, thermography has become a common tool for helping to detect moisture damage. Knowing when and how to conduct an infrared inspection is key to success.
Water infiltration into buildings can have devastating effects on building materials. Left untreated, latent moisture can cause excess energy loss, mold growth and/or structural failure. Latent moisture also causes changes in the thermal capacitance and conductivity of materials.
Prior to performing an infrared inspection, determine the best vantage point for imaging. Insulated roofs and exterior building finishes such as EIFS are traditionally inspected from the exterior of the building. Interior inspections are usually effective when moisture is affecting interior finishes of the building such as drywall. Thermal imaging may not be effective for low emittance targets.
Next, choose an appropriate time to ensure that a detectable Delta T will be present. For roofs and building exteriors, best results are usually obtained during evening hours following a sunny day. As an alternative, inspections may also be performed when there is an inside/outside temperature differential of at least 10Cº. In some cases, inspections performed from the interior may be performed with a smaller Delta T.
Thermal signatures associated with latent moisture will vary with type of building material and the amount of moisture contained therein. Depending upon vantage point and time of inspection, exceptions caused by latent moisture may show as either hot or cold thermal anomalies. These anomalies may be amorphously shaped, mottled, or correspond to the size and shape of absorbent materials. All thermal data should be correlated with invasive testing to ascertain moisture content of inspected areas.
Infrared inspections of building envelopes is one of the many topics covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. For more information on class locations or our Distance Learning program, visit www.infraspection.com or call 609-239-4788.
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 videotape 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 on 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.
Infraspection Institute and Kleinfeld Technical Services, Inc. are preparing Distance Learning Tutorials on a variety of topics. We would appreciate your feedback as to your interest areas for these tutorials. Please fill in the very short survey at this link: http://www.surveymonkey.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.
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.
IR Inspections for Sewer Systems
In regions with older infrastructure, sewer system integrity is often a primary concern. Under the right conditions, thermography can often detect sewer leaks or voids surrounding the system that can lead to sinkholes.
In the case of sewer systems, thermal imaging is usually employed during evening hours after a sunny day. During the inspection, the thermal imager is maneuvered over the pathway of the subject sewer system looking for unusual thermal patterns. The imager may be operated on foot, from a motor vehicle or an aircraft.
Sewer system defects which may be detectable include leaks to surrounding soil and voids around sewer piping. The detectability of these defects will be largely dependent upon:
- Depth of sewer system
- Amount of loss
- Pipe construction
- Soil type and ground cover
One should be aware that a negative finding does not necessarily mean defects are not present; they simply may not be detectable by thermal imaging. Conversely, positive findings can be caused by conditions other than leaks. Therefore, it will be necessary to verify all thermal data by visual inspection.
The topic of infrared inspections of buried piping systems is covered in depth in our Level I Certified Infrared Thermographer™ training course. For more information on class locations or our Distance Learning program, visit www.infraspection.com or call 609-239-4788.
How to Core Sample a Roof
Currently published industry standards require that core samples be obtained when performing infrared roof moisture surveys. Properly procuring and patching core sample sites can help to maintain watertight integrity of sample sites.
Core sampling a roof involves physically removing a portion of the roof membrane and insulation layers to ascertain the composition and condition of roofing system components. Core samples may be square or round and range from a couple of inches in diameter to several square feet in size.
The following procedure outlines the steps in sampling and patching 2” diameter core samples on gravel-surfaced, built-up roofing systems.
- Locate sample site on flat portion of roof not subject to ponding
- Spud gravel off membrane for 12” diameter area. Use wire brush to remove dust
- Use core cutter to sample through membrane down to deck. Do not cut through roof deck
- Fill sample hole approximately ¾ full with cold roof mastic compatible with existing roof bitumen
- Install plug made from perlite insulation. Cold mastic should flow up and around plug once it has been seated firmly on roof deck at bottom of hole. Top of plug should be within 1/8” of top of sample hole when plug has been pushed to bottom
- Coat cleared area with roof mastic
- Center 6” diameter disk of 15 lb roofing felt over plug. Firmly press felt down to remove air pockets and fish mouths
- Apply thin layer of roof mastic over 6” felt
- Center 12” diameter disk of 15 lb roofing felt over plug. Firmly press felt down to remove air pockets and fish mouths
- Apply generous layer of roof mastic over 12” felt. Replace gravel and outline area with spray paint
Prior to sampling, determine if roof is under any warranty that could be voided by sampling. Always obtain permission to perform any invasive testing before you begin.
Infrared inspection of flat roofs is one 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 online or call us at 609-239-4788.
It’s Not That Easy
Ever wonder why magicians never reveal their secrets? It’s because magic, like most things, is easy once you know the trick. When describing thermography in lay terms, it is easy to over emphasize simplicity and forget the source of the true magic behind thermography – the thermographer.
An infrared inspection system consists of infrared imaging equipment, a thermographer, and the knowledge that he/she possesses. Of these three things, the greatest limiting factor in an infrared inspection is the thermographer.
In order to be an effective thermographer, one must be trained in the following:
- Theory and construction of the object or system being inspected
- Infrared theory and heat transfer principles
- Use and operation of infrared imaging equipment
- Non-contact temperature measurement error sources and how to avoid or correct for them
- Site-specific safety requirements and the use of appropriate PPE
In addition to the above, qualified thermographers must also be experienced with inspecting the subject system. When all things are considered, effective thermographers need considerable training and field experience. Making thermography look simple is a true testament to the skills of a professional thermographer.
The next time you hear the dismissive claim that thermography is easy, remember, it is only easy after someone has invested considerable time and effort to learn the art and science of the trade. In a magic show, the magic comes from the magician, not the wand. In thermography, the magic comes from the thermographer.
Visit Infraspection Institute online or call us at 609-239-4788.
Role of IR Inspections for Electrical Distribution Systems
Infrared inspections can be a valuable tool for detecting problems within electrical distribution systems. Understanding when and where to utilize thermography is key to obtaining maximum benefit.
Infrared inspections can detect and document evidence of loose/deteriorated connections, overloaded circuits, imbalanced loads, harmonics, and defective equipment. In some cases, infrared inspections can detect evidence of problems that may be overlooked by traditional electrical testing. Infrared inspections should be used to supplement, but not replace, regular preventive maintenance.
When setting up an IR inspection program for an electrical distribution system, keep the following in mind:
- Inspections should be performed at least annually
- Inspections should be conducted with the electrical system under normal load
- Inspections require clear line-of-sight to inspected components
- When possible, IR inspections should be performed 4 to 6 weeks in advance of a PM shutdown to allow time to order any necessary parts
- Exceptions should be reinspected after repair to help ensure that repairs were effective
- All new/retrofitted equipment should be inspected within 24 hours of installation
- All findings should be documented in writing in accordance with the Standard for Infrared Inspection of Electrical Systems and Rotating Equipment
Lastly, infrared inspections should only be performed by certified infrared thermographers who possess appropriate safety training and are thoroughly familiar with the system(s) being inspected.
For more information on thermographer training and certification or to obtain a copy of the Standard for Infrared Inspection of Electrical Systems and Rotating Equipment, contact Infraspection Institute at 609-239-4788 or visit us online at www.infraspection.com.