When performing an electrical system inspection, don't forget to record electrical load on the subject circuits. Doing so will not only enable you to duplicate your inspection efforts during a follow up inspection but will also allow you to make meaningful assessments when trending either absolute temperatures or delta Ts.

Ammeter readings should always be taken with a true RMS sensing ammeter for accurate load readings.

Ambient temperature is a term which appears in nearly all thermographic reports. However, many thermographers define ambient differently. Some define it as room air temperature while others define it as the temperature inside of the component enclosure.

According to the IEEE, for electrical components ambient temperature is the environmental temperature immediately surrounding the subject component. For devices located within enclosures, this is the temperature within the enclosure while it is closed and operating. For components in free air, it is the temperature surrounding the component.

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.

When testing traps, begin by using your thermal imager to ascertain that steam is reaching the trap. The trap inlet should be above 212 F. Next, listen to the trap outlet with your ultrasonic unit. Although traps should cycle periodically, you should not hear a continuous hissing or rushing sounds.

While it takes some practice to become proficient with ultrasonic testing, the increased accuracy is worth the effort.

When performing an infrared inspection of low slope roofs, it is imperative to verify thermal data with destructive testing. While infrared imagers can detect temperature changes associated with missing and damaged insulation, they cannot ascertain the cause of the thermal image.

Core sampling or invasive moisture meter readings are the only known methodologies for accurately determining moisture content. Coupling invasive verification with thermal imaging not only improves accuracy of the inspection but also is required by ASTM Standard C1153.

When doing Thermographic Surveys, often the certified Thermographer will want to reference the exception he or she is viewing in the Infrared Image with an arrow or point in the visual digital image.

By using either a Laser Pointer or a Pyrometer with a Laser aiming device, while shooting the picture the red spot from the laser will show up in the digital photo and eliminate
the need for a reference arrow in the visual display photo of the report.

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.

1) 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.

2) Equipment: For highly reflective and smooth surfaced roofs , use a short wave (3-5 micron) imager to overcome reflections caused by nightime sky. For gravel or granule surfaced roofs, you may use either a long wave or short wave camera with good results.

3) 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 that 15 mph at the rooftop during IR inspection
• No rain on day of infrared inspection

4) 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.

5) 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.

6) 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.

7) Moisture Verification: To ensure accuracy all infrared data must be verified through invasive testing and the results correlated to infrared data. Remember, an infrared imager is not a moisture meter.

8) 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.

For additional information, you may wish to check out the following documents:

• ASTM C-1153 Standard Practice for the Location of Wet Insulation in Roofing Systems Using Infrared Imaging
• Infraspection Institute Guideline for Performing Infrared Inspections of Building Envelopes and Insulated Roofs
• For information on training, contact Infraspection Institute. Our Level I Certified Infrared Thermographer Course is taught by field experienced instructors with extensive knowledge in infrared inspections of flat roofs.
  

Budgeting for infrared test equipment can be a daunting task. Prices for infrared test equipment vary widely depending upon the type of instrument and equipment features. There are generally three categories of infrared test equipment:

1) Non-imaging radiometers
2) Thermal imagers
3) Imaging radiometers

Non-imaging radiometers, often referred to as infrared pyrometers, point radiometers or spot radiometers, produce temperature data by detecting the invisible infrared radiation emitted by an object and converting this energy into a temperature value. These temperature values may be displayed in either analog or digital fashion in either Celsius or Fahrenheit.

Non-imaging radiometers may be either hand-held or permanently mounted for continuous temperature monitoring or can be integrated with a computer for automatic process control.

Most modern, hand-held radiometers employ a laser sighting system to enable the user to help aim the instrument. Hand-held radiometers are best suited for taking non-contact temperatures of stationary electrical or mechanical equipment at close distances.

Prices for hand-held non-imaging radiometers range from $100 to $3000 depending upon features and capabilities. Permanently-mounted radiometers can range in price from $1000 to over $100,000.

For more information on non-imaging radiometers, please visit: www.irinfo.org/radiometer_mfgrs.html

Thermal imagers are video camera like devices which convert invisible infrared radiation emitted by an object into a monochrome or multi-color image on a monitor screen wherein the various shades or colors represent thermal patterns across the object's surface.

Prices vary widely for thermal imagers depending upon features and capabilities.

For monochrome thermal imagers, prices start at less that $10,000 for lower resolution systems and range to over $100,000 for high resolution airborne systems. Thermal imagers are most often used in surveillance or in applications where temperature measurement is not required.

Imaging Radiometers. Simply put, imaging radiometers are thermal imagers that can also measure temperatures. Imaging radiometers have a wide variety of uses in maintenance, aerospace, research & development, quality assurance, condition monitoring and forensic applications.

Once again prices vary widely depending upon features and capabilities such as image storage and available software for post processing of images and data. Pricing for imaging radiometers begins around $15,000 and can exceed $50,000 depending upon how the system is configured.

For more information on thermal imagers and imaging radiometers, please visit: www.irinfo.org/imager_mfgrs.html

Because equipment varies widely in its capabilities, it is imperative that buyers and users of infrared test equipment fully understand how to properly choose an instrument for the task at hand.

Lastly, the greatest limiting factor in an infrared inspection is the equipment operator. Relying on data 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. For training and certification courses for thermographers, please visit: www.infraspection.com.

You can check infrared imagers and radiometers for temperature measurement accuracy using blackbody simulators. To do this you will need two separate blackbody simulators with known temperatures and known emittances. The complete procedure takes very little time and is detailed in Infraspection Institute's Level II Certified Infrared Thermographer Reference Manual. In following this procedure and using a standard reference, you will be calibrating your IR instrument.

If you prefer not to follow the above procedure or if determine that your camera is out of calibration, you will have to return it to the manufacturer for calibration adjustment. Unfortunately, there are no independent laboratories who perform calibration adjustments since the procedures for doing so are considered proprietary and are maintained as trade secrets by infrared equipment manufacturers. As such, you must return infrared equipment to the manufacturer for any calibration adjustments.

Calculating savings and/or avoided costs is one of the most difficult tasks associated with an infrared inspection program; however, doing so is required in order to gauge how effective a program is.

In short, there is no way to calculate the exact value of the findings of an infrared inspection other than allowing the component run to failure and adding up the subsequent losses. Unfortunately, this is not a practical approach to maintenance.

As an alternative, there are several methods that professionals use to estimate program savings. A brief description of each of the most common methods is listed below:

1. Summary of Findings - A report comprised of the deficient items found during a given time period. Reports may be by the day, month, year, etc. This type of report does not provide any financial data.

2. Performance Effectiveness Ratios - Use accounting data to trend how an infrared inspection program impacts an overall maintenance program. Typically calculated for a single facility over an extended period of time. Improvements in efficiency can be compared to similar facilities or to the performance history subject facility.

3. Avoided Costs Method - A summary of the estimated cost of repairs for breakdown versus proactive repair efforts. Typically, proactive repairs are always cheaper since the outage can be planned and the cost of the actual repair is usually less since the subject equipment often suffers far less damage when not allowed to run to catastrophic failure.

4. Permanent Improvement Method - This is a summary of the financial impact on a given facility due to the implementation of an infrared inspection program. For example, infrared can be used to supplement a maintenance program by directing repair efforts to only those areas in need of attention rather than periodic application of labor-intensive manual work. In such cases, the cost difference between the two methods results in a savings every time the manual maintenance procedure is avoided in the future.

5. Statistics Based Method - This method is based upon insurance industry statistics associated with loss claims that have been paid to clients over a several year period. This method takes into account the value of the overall facility along with the severity of the problem. While this method is not as accurate as the Avoided Cost Method, it can be applied quickly and easily with a minimum of effort. Infraspection Institute's Exception 2000™ software utilizes this method for calculating savings as one of its standard features.

Each of the above methods varies in the information provided as well as the ease of use and accuracy. We cover each method in depth in our Level III Certified Infrared Thermographer Course.

When calculating savings, we recommend that thermographers consult with their end user and choose one of the above methods that will best suit his/her needs and consistently apply the chosen method over time. While you will not be able to calculate savings exactly, you should obtain a good indication of the value of your program.

Infrared thermography offers good potential for detecting energy losses from process equipment and piping as well as some symptoms of pipe deterioration.

It is important to remember that thermography is a line-of-sight technology that detects thermal patterns and associated temperatures across the surface of an object.

Subsurface characteristics or defects cannot be detected by thermography unless they cause a temperature differential of at least 0.1 Celsius degrees across the surface of the object being inspected. Presently, interior corrosion detection is best detected with ultrasonic thickness testing; exterior corrosion may be detected by visual examination.

Thermography may prove useful if corrosion is being caused by water saturated insulation surrounding your process piping. If this is the case, water saturated insulation should show excess energy loss at the point where the water is entrapped. It will be necessary to visually inspect the pipe to confirm the actual condition of the pipe.

When performing thermal imaging, be aware that weather conditions such as solar gain, wind and atmospheric attenuation can adversely affect your results. Be certain that your imaging system is capable of detecting the anticipated defect by understanding how emissivity, spectral response and spot size will affect your inspection.

Should you require further information on thermography or to obtain a course schedule, please feel free to visit www.infraspection.com.

Proper camera sensitivity is imperative when performing infrared inspections of low slope roofs. When performing an infrared inspection it is necessary to adjust level and gain settings depending upon the area or roof component being inspected.

In most cases, base flashings will require lower or less sensitive settings than the field of the roof. This is due to the fact that base flashing areas contain more mass than uninterrupted roof membrane and will typically radiate more heat than the open field of the roof.

When inspecting areas with greater density such as base flashings, it is important to concentrate on these areas and to qualitatively compare them to similar roof details.

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.

1) 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.

2) Equipment: For highly reflective and smooth surfaced roofs , use a short wave (3-5 micron) imager to overcome reflections caused by nightime sky. For gravel or granule surfaced roofs, you may use either a long wave or short wave camera with good results.

3) 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:

• a) Recent rain sufficient to cause wetting of roof components
• b) Dry roof surface at sunrise. No ice, snow or standing water
• c) Mostly sunny day
• d) Daytime highs above 40 F
• e) Daytime winds of less than 15 mph at the rooftop
• f) Nightime winds of less that 15 mph at the rooftop during IR inspection
• g) No rain on day of infrared inspection

4) 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.

5) 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.

6) 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.

7) Moisture Verification: To ensure accuracy all infrared data must be verified through invasive testing and the results correlated to infrared data. Remember, an infrared imager is not a moisture meter.

8) 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.

For additional information, you may wish to check out the following documents:

• ASTM C-1153 Standard Practice for the Location of Wet Insulation in Roofing Systems Using Infrared Imaging
• Infraspection Institute Guideline for Performing Infrared Inspections of Building Envelopes and Insulated Roofs
• For information on training, contact Infraspection Institute. Our Level I Certified Infrared Thermographer Course is taught by field experienced instructors with extensive knowledge in infrared inspections of flat roofs.
  

Infrared thermography offers good potential for detecting energy losses from process equipment and piping as well as some symptoms of pipe deterioration.

It is important to remember that thermography is a line-of-sight technology that detects thermal patterns and associated temperatures across the surface of an object.

Subsurface characteristics or defects cannot be detected by thermography unless they cause a temperature differential of at least 0.1 Celsius degrees across the surface of the object being inspected. Presently, interior corrosion detection is best detected with ultrasonic thickness testing; exterior corrosion may be detected by visual examination.

Thermography may prove useful if corrosion is being caused by water saturated insulation surrounding your process piping. If this is the case, water saturated insulation should show excess energy loss at the point where the water is entrapped. It will be necessary to visually inspect the pipe to confirm the actual condition of the pipe.

When performing thermal imaging, be aware that weather conditions such as solar gain, wind and atmospheric attenuation can adversely affect your results. Be certain that your imaging system is capable of detecting the anticipated defect by understanding how emissivity, spectral response and spot size will affect your inspection.

Should you require further information on thermography or to obtain a course schedule, please feel free to visit www.infraspection.com.

Budgeting for infrared test equipment can be a daunting task. Prices for infrared test equipment vary widely depending upon the type of instrument and equipment features. There are generally three categories of infrared test equipment:

1) Non-imaging radiometers
2) Thermal imagers
3) Imaging radiometers

Non-imaging radiometers, often referred to as infrared pyrometers, point radiometers or spot radiometers, produce temperature data by detecting the invisible infrared radiation emitted by an object and converting this energy into a temperature value. These temperature values may be displayed in either analog or digital fashion in either Celsius or Fahrenheit.

Non-imaging radiometers may be either hand-held or permanently mounted for continuous temperature monitoring or can be integrated with a computer for automatic process control.

Most modern, hand-held radiometers employ a laser sighting system to enable the user to help aim the instrument. Hand-held radiometers are best suited for taking non-contact temperatures of stationary electrical or mechanical equipment at close distances.

Prices for hand-held non-imaging radiometers range from $100 to $3000 depending upon features and capabilities. Permanently-mounted radiometers can range in price from $1000 to over $100,000.

For more information on non-imaging radiometers, please visit the radiometer page.

Thermal Imagers: Thermal imagers are video camera like devices which convert invisible infrared radiation emitted by an object into a monochrome or multi-color image on a monitor screen wherein the various shades or colors represent thermal patterns across the object's surface.

Prices vary widely for thermal imagers depending upon features and capabilities.

For monochrome thermal imagers, prices start at less that $10,000 for lower resolution systems and range to over $100,000 for high resolution airborne systems. Thermal imagers are most often used in surveillance or in applications where temperature measurement is not required.

Imaging Radiometers: Simply put, imaging radiometers are thermal imagers that can also measure temperatures. Imaging radiometers have a wide variety of uses in maintenance, aerospace, research & development, quality assurance, condition monitoring and forensic applications.

Once again prices vary widely depending upon features and capabilities such as image storage and available software for post processing of images and data. Pricing for imaging radiometers begins around $15,000 and can exceed $50,000 depending upon how the system is configured.

For more information on thermal imagers and imaging radiometers, please visit the imager page.

Because equipment varies widely in its capabilities, it is imperative that buyers and users of infrared test equipment fully understand how to properly choose an instrument for the task at hand.

Lastly, the greatest limiting factor in an infrared inspection is the equipment operator. Relying on data 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. For training and certification courses for thermographers, please visit: www.infraspection.com

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 only see a portion of the target.

Wide angle lenses increase an imager's 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.

Many people think about the heating season and the thermal performance of their homes and offices. Thermal imaging can be extremely useful in identifying areas of excessive heat loss or air leakage. The effectiveness of an infrared inspection will depend upon how the inspection is performed.

A common misconception is that infrared inspections are performed merely by looking at the exterior surfaces of a building from the outside of the structure. While this practice may identify gross defects for some structures, it usually fails to detect more serious defects such as air infiltration and heat distribution problems within the building.

For best results, infrared inspections of buildings should be performed from the inside of the building when there is a minimum inside/outside temperature differential of 10 Celsius (18 F) degrees for several hours prior to, and during the inspection. The inspection should include all exterior walls, windows, doors and ceilings imaged from the interior of the building. Performing the inspection on a calm night will eliminate errors due to solar loading and wind. Additionally, the building HVAC system should be operated under normal conditions. For commercial buildings this may involve overriding the HVAC system controls to duplicate daytime settings.

If you are concerned about the thermal performance of your building, the best time to conduct an infrared inspection is at the beginning of the heating season. Performing your inspection now will enable you to make necessary repairs before the cold weather sets in.

As always, a certified, experienced thermographer will help to ensure that you receive accurate and reliable data.

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 see 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.

Although thermography has gained wide acceptance for use in P/PM, Condition Monitoring and Forensics, thermographers often are unaware of the existence of published safety standards regarding infrared inspections.

The following is a partial list of currently distributed safety standards along with the organizations who publish them. Contact these organizations directly to obtain copies.

• National Fire Protection Association, Quincy MA
• NFPA 70E Standard For Electrical Safety Requirements for Employee
  Workplaces
• Occupational Safety and Health Administration
• 29 CFR Part 1910 Occupational Safety and Health Standards for General
  Industry
• 29 CFR Part 1926 Occupational Safety and Health Standards for General
  Construction

It should be noted that many workers (miners, transportation, many federal workers) are exempt from OSHA standards; however, there are often agencies similar to OSHA who publish applicable standards for these workers.

Infrared Inspections are often performed in hazardous environments. Safely conducting an infrared inspection should be of paramount importance for all involved. Prior to beginning an infrared inspection, a thermographer must be aware of which safety standards apply to his/her work.

The Infraspection Institute Level 3 Certified Infrared Thermographer covers thermographer safety and applicable standards in depth. For more information, contact Infraspection Institute at 609-239-4788 or online at www.infraspection.com

Performance Standards and Specifications for Thermography

Although thermography has gained wide acceptance for use in P/PM, Condition Monitoring and Forensics, thermographers often are unaware of the existence of published standards and specifications regarding infrared inspections.

The following is a partial list of currently distributed performance standards and specs along with the organizations who publish them. Contact these organizations directly to obtain copies.

• American Society for Testing and Materials, West Conshohocken, PA
• ASTM C 1060-97 Practice for Thermographic Inspection of Insulation Installations in Envelope Cavities of Frame Buildings
• ASTM C-1153-97 Practice for the Location of Wet Insulation in Roofing Systems Using Infrared Imaging
• ASTM E 1316-97 Terminology for Nondestructive Examinations
• ASTM E 1862-97 Standard Test Methods for Measuring and Compensating for Reflected Temperature Using Infrared Imaging Radiometers
• ASTM E 1933-97 Standard Test Methods for Measuring and Compensating for Emissivity Infrared Imaging Radiometers
• ASTM E 1934-97 Standard Guide for Examining Electrical and Mechanical Equipment with Infrared Thermography
• Infraspection Institute, Burlington, NJ
• Guidelines for Infrared Inspection of Building Envelopes and Insulated Roofs
• Guideline for Measuring Distance/Target Size Values for Quantitative Thermal Imaging Cameras
• Guideline for Measuring and Compensating for Reflected Temperature, Emittance and Transmittance
• Guidelines for Infrared Inspection of Electrical and Mechanical Systems
• International Electrical Testing Association, Morrison, CO
• Acceptance Testing Specifications for Electrical Power Distribution Equipment and Systems
• Maintenance Testing Specifications for Electrical Power Distribution Equipment and Systems
• National Fire Protection Association, Quincy MA
• NFPA 70B Recommended Practice for Electrical Equipment Maintenance

Proper conduct of an infrared inspection and interpretation of data require thorough training and certification by a recognized training agency. For more information on training and certification, contact Infraspection Institute at 609-239-4788 or online at www.infraspection.com

Choosing the proper equipment for an infrared inspection is of paramount importance when performing an infrared inspection.

Each model of infrared imaging system has many unique operating characteristics which must be considered before a project is undertaken. Of these, perhaps the most important is spectral response.

Spectral response for an imager generally falls into two categories: 2-5 microns (near infrared) or 8-14 microns (far infrared). Because spectral response can limit one's ability to perform certain types of inspections, it is critical that a thermographer understand how spectral response can affect his/her work.

Below are some generally recommended spectral responses for different types of P/PM applications.