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ARMCO General Infrared FAQs

What is infrared imaging or Thermography and how does it work?

Thermal imaging is the process of recording pictures of the patterns or variations of heat radiated from a surface of a device or other object (machine face or component, wall, roof, street, electrical component, etc). Thermal imagers do not see through things as shown on the telly, they only “see” the heat radiation resulting from variations of temperature on the surface. It is up to the thermographer to understand the underlying device or component construction, the affect on heat transfer and the resulting surface heat or thermal patterns in order to properly interpret the image.

The graphic below gives an idea what is going on physically:

Total-Infrared-System-02

Why will an Infrared Inspection help me with my problem?

Infrared Imaging with associated image confirming techniques has been documented repeatedly to be the fastest and most cost effective methodology for the assessment of roof or electrical system overall condition for targeted and timely repairs . It is also a major tool in the location and assessment of interior moisture or water leakage as well as energy loss through air leakage or poor insulation.

  • For electrical and rotating mechanical systems, components and bearings heat noticeably before failure. The resulting variation in surface or relative temperature can easily be detected with a thermal imager prior to failure and repaired or replaced.
  • Inside a building, evaporating water or moisture from leaks or condensate will cool the surface that is wet relative to the surrounding area and that variation is “seen” by a thermal imager.
  • In a leaking or moisture contaminated flat roof, the trapped moisture beneath the surface retains heat as the roof cools at night resulting in temperature variations on the surface of the roof which are detected with a thermal imager and marked for repair or replacement
  • Missing or poorly installed insulation in a residence or building will result in variation in heat transfer from the outside or vice-versa and that will create variations or patterns of heating on the wall surfaces – again detected with a thermal imager
  • Building or residence air leakage from inside to outside or vice-versa will cause thermal variations on the walls or areas where the leak occurs which targets the area for repair

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Why should I use Armco Infrared?

Because our clients suggest that they have had a good experience and you will as well – Click here to read what clients have said.

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Beyond thermographer experience and competence, what factors can create problems or affect the results of an Infrared Inspection?

  • Focus of the imager lens
  • Temperature Sensitivity and Noise Rejection of the imager detector and electronics
  • Thermal Imager Viewing Angle: Shiny/smooth surfaces can easily reflect heat/cold radiation from other places that mask what is actually being radiated from the surface – as in cold reflections from the sky off a smooth plastic or metallic coated roof
  • Thermal Imager frequency response Short-wave vs long-wave imagers: One or the other is better at certain applications – Check out the differences between the T620 and PM290 Armco imagers in Tools of the Trade)
  • Underlying Structure of the object being viewed and the effect on heat transfer
  • Surface Finish of the viewed object: A shiny metal or plastic surface can appear much cooler than it actually is and the variations of surface temperature very slight as it radiates much less resulting in poorly defined thermal patterns. There are settings within the imager to partially compensate for the surface finish but the challenge is there. Short wave/mid wave imagers may do a better job with these difficult conditions
  • Surface Shape: Round stuff will have maximum radiation and appear brighter at places that are perpendicular or square with camera lens) and holes will appear warmer due to the concentration of radiation within the hole or depression
  • Radiation wavelength: Longer wavelength/lower frequency appears cooler and shorter wavelength/higher frequency appears warmer)

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Since infrared imaging only “sees” the surface temperatures, how do we really know that there is moisture present behind a wall or beneath the roof surface?

For roof inspections we use a number of techniques and instrumentation both intrusive and non-intrusive to verify or confirm the thermal imaging. Intrusive testing includes both core removal and examination as well as the insertion of moisture meter probes sensitive to electrical conduction in water. Non-intrusive testing includes both capacitive and nuclear gauge moisture metering. Similar intrusive and non-intrusive techniques may used inside the building for moisture inspections

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How many people does it take to do an infrared inspection or assessment?

Crew size depends primarily on safety requirements and secondarily on the complexity or demands of the task. For roof work at night, a minimum of two are required for safety, roof marking and data recording. For electrical work, an additional person is required to open the panels and provide fault severity information for the installation. For energy and interior moisture work, generally a single person, the thermographer, is sufficient.

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How long will the inspection or survey take and what time of day is the work performed?

With the exception of roof work, our infrared inspections are performed during the day. Roof inspections are routinely performed at night and during the day in order to observe the roof as it cools and/or as it warms (it is a “transition game”). The length of time for any job depends on several factors including job complexity and distance from home base in Raleigh. Infrared roof inspections are highly weather dependent as we require dry surfaces in addition to solar heating for surface warming and clear night skies for membrane cooling.

Time investment for roof work varies with the roof size, number of sections, roof equipment density, age and construction type. For electrical jobs, the time factors include the number of devices or panels to be opened as well as the arc-flash hazard. For moisture and energy work, the size of the building or the extent of the moisture intrusion are major factors.

Firm quotations are provided on request and after we gain a good understanding of the factors that will affect the site inspection, report write-up and post-report consulting time required. We will also provide verbal ball-park pricing prior to written quotations as necessary.

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What is Infrared or infrared radiation – really?

Radiation is one of the three methods of heat transfer as seen in the graphic below. In the business of thermography, we need to be aware of all three as they affect the images that we interpret.

Thermal or heat energy is conveyed from a point of higher to relatively lower energy level in three different but partially related ways:

  1. Conduction (direct contact with another object),
  2. Convection (direct contact with a gas or fluid which is heated and then moves to a cooler area or space drawing cooler air in to take its place) and
  3. Radiation (the movement of waves of thermal energy through space at light-speed away from a relatively hotter source)

Convection

Thermal Imagers are sensitive to the RADIATION from a surface that is proportional to the energy of the surface or the temperature of that surface. A thermal imager display may show a warmer device or area as lighter in color or a different color than an area that is cooler.

Infrared radiation is part of the electromagnetic spectrum as shown in the graphic below:

Electromagnetic

The frequency of occurrence or distance between waves (wavelength) of thermal energy radiation occurs below that of visible light and is therefore invisible to the human eye. The band of frequencies or wavelengths in which thermal energy radiation occurs is called infrared as can be seen in the vivid illustration above that contains the entire electromagnetic spectrum (infrared = below visible red). The Thermal Imager is designed to “see” thermal energy radiation in the infrared region of the electromagnetic spectrum.

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