ITC E-LearnIR Courses receive RCI Accreditation

The ITC Building IR Basics and Thermography Basics E-learning courses now earn credit with RCI for two RCI Continuing Educational Hours (CEHs). These are noted on the certificates of completion.

You can find the courses at ITC Online Portal

How Emissivity affects Heat Transfer and Surface Temperature

A reader writes:

"I know the higher the emissivity a surface has the greater its ability to absorb heat (IR), however, is a painted surface able to reject or shed heat better? An example would be does a painted engine run cooler than a unpainted metal engine or hotter or the same temp?"

If an object has a higher temperature than its environment, then increasing its emissivity will certainly lower its temperature. As an example, lets look at the motor in the illustration. It has a cover made of stainless steel and is very shiny. Let's assume its emissivity is 0.1.  We have measured its steady state temperature at 150 F. The rate of heat generation of the motor has to be exactly balanced by the rate of heat loss from the motor. So, in this case for simplification, we will only consider convection and radiation. The numbers are shown in the illustration.

Now, if we painted the motor with flat white paint, the heat transfer will change. We still have to get rid of the 66 Btu/hr being generated by the motor, but if we assume a new emissivity of 0.9, then the huge increase in the radiation loss will reduce the surface temperature to 118 F as shown.

IR Transparent Materials for Windows and Lenses

"Which material (Quartz or Sapphire) has better transparency to IR spectrum? Is there any material that is totally transparent to entire IR spectrum?"

The chart below illustrates a variety of materials and the wavelengths at which they transmit.


 

Courtesy http://www.ispoptics.com

Here are detailed data sheets on quartz and sapphire.

"Which IR (Near IR or Far IR ) carries more thermal energy?"

Photons at shorter wavelengths of IR carry more energy. So all other things being equal, will produce more heating on an absorbing surface.

"While traveling through the IR transparent lens will be there any damage to the lens?"

Any infrared energy absorbed by the lens will produce some heating. Anti-reflective coatings are commonly applied to lens systems to reduce absorption and improve the transparency.

For more information please contact:

ISP Optics Corporation
1 Bridge Street, suite 205
Irvington, NY 10533, USA
Tel: 914-591-3070, 800-909-4207
Fax: 914-591-3715
E-mail: sales@ispoptics.com 
Web Site: http://www.ispoptics.com/

Check out the new Application Tracks at InfraMation

This year at InfraMation, we are introducing application tracks to make it easier for attendees to select the sessions that will best fit their needs at the conference. We have so many sessions and short courses, its impossible for anyone to attend them all. In fact out of the 36 technical sessions available, attendees only have time to attend a maximum of 16, less than half! Here are the tracks.

Buildings Track - Consists of 3 paper sessions, 1 panel discussion, and 6 short courses.

Condition Monitoring Track - 3 paper sessions, 4 panel discussions, and 8 short courses.

Medical Track - 3 paper sessions, 1 panel discussion, and 1 short course.

R&D Track - 3 paper sessions, 5 short courses.

You can find these tracks, subjects, and schedules in the at a glance chart to the right.
in reference to: Welcome to InfraMation - Thermographer's Conference (view on Google Sidewiki)

Marketing your infrared thermography services

This is an increasingly common request these days. As the prices of infrared cameras has dropped dramatically in the past few years, more and more independent consultants have been purchasing them. These users don't have large corporations and big marketing budgets to promote themselves.

"I love being a thermographer and would appreciate any suggestions you may have on how I can develop more effective ways to build my business?"

So you have to come up with smart low cost ways of getting noticed, and getting business. Here are a few suggestions:

Speak at local trade associations meetings. They are always looking for speakers. Some examples:

• Building Owners and Managers Association International
• IEEE
• RCI
• Association of Energy Engineers

Call up or email local TV stations with interesting images or video you have taken with your IR camera. Examples:

• Current news events - Forest fire, Search for lost child
• Consumer concerns - Heating or A/C costs, Mold in schools

Build a web site and make sure search engines can find it

Find messageboards and blogs and contribute to them

Use social networking media like Linked In and Facebook to network

Search Business and Manufacturers Guides for potential clients

• Shopping Centers
• Office complexes
• Warehouses
• Supermarkets
• Manufacturing Facilities

Here is an example of an online directory, Directories USA. You could search for parameters that could point to a good prospect such as:

• Number of employees
• Facilities Square footage
• Electrical Useage
• What they make
• Plant Manager contacts

Put a video up on YouTube

Quick and Easy Solution to Emissivity Problems

"We've received the camera and so far it's been good in that department. I am concerned however about emissivity. In my application, I'm filming the inside of a computer system which is a small, tightly packed space with different materials and emissivities. Because thermography is something new to me, I'm not sure how much of a role emissivity plays in throwing off my measurements. I could attach a thermocouple to each component to verify the readings on the thermal cam, however that's very time consuming and given the limited amount of time I have with this instrument, it doesn't make sense. I've read that there's emissivity sprays that will help with this issue but don't know if that solution is any better or cost effective. Do you have any cheap and quick solutions for my problem?"

Yes, emissivity can play a big role in your temperature measurement accuracy, especially if you are trying to measure shiny metals. Here is what I would do:

Measure your reflected apparent temperature

1. Set camera emissivity to 1.0
2. Use some slightly crinkled aluminum foil and place next to your target(s).
3. Using the area mode of your camera set to average temperature, read the apparent average temperature of the aluminum foil. (Be careful that you don't reflect your own heat reflection of the foil).
4. Enter this temperature as the reflected temperature in your camera.

Measure your target(s)

1. Use some Liquid Paper brand correction fluid.
2. Place a small amount on your targets.
3. Set your camera emissivity to 0.95
4. Measure the temperature of your target(s)

Cautions and Caveats

• When using these techniques make sure that the correction fluid will not damage your components.
• Use a small amount of correction fluid. Changing the emissivity of small shiny components from less than 0.1 to 0.95 will greatly affect the heat transfer from these components, and thus affect their temperature. So the smallest amount of emissivity improver that you can measure is the amount to use. This is easy on FLIR systems cameras, just make sure that the emissivity improver is large enough to fill the cursor circle on the spot tool. Anything smaller will not be measured correctly.
• There are more sophisticated ways of doing this automatically for all materials on a PCB through software. Please contact a FLIR Systems Scientific Segment Engineer regarding Altair software.
• If you don't understand emissivity and reflected apparent temperature terms, get some training! A good place to start is this web based course, Thermography Basics.

How can one tell if the imager needs calibration?

Most manufacturers suggest that an IR camera be serviced with a calibration check annually, like many other instruments. The checklist below outlines the FLIR annual service program. 

FLIR 14 POINT INSPECTION & CALIBRATION PROGRAM

1. Perform a complete operational check
2. Fusion calibration and laser alignment, when applicable
3. Verify all internal cable and PCB connections
4. Clean viewfinder and check optics
5. Upgrade internal camera software to latest revisions
6. Perform minor repairs
7. Verify and/or re-equalize as needed each temperature range for image uniformity
8. Verify standard lens calibration (others or special engineered lenses, optional)
9. Verify ambient temperature compensation as needed
10. Re-calibration to ensure it meets factory specification
11. Calibrate temperature ranges up to +1,500°C, when applicable
12. Perform quality approved acceptance test procedure
13. Provide calibration label with next due date
14. Provide calibration certificate (optional, extended calibration certificate with measured values)

 Here is a quick way you can check your camera calibration in the field:

1. Measure the temperature of a MELTING ice cube. The reading should be 0 C +/- 2 C.
2. Measure the temperature of boiling water (if you are near sea level). Reading should be 100 C +/- 2 C

Thermography Weatherization Certification course earns BPI CEUs

The Weatherization certification course has been approved by BPI for 16 CEUS. It was previously approved by RESNET for 32 CEUS.

The 4 day certification course is intended to give the student a depth of the knowledge necessary to perform IR surveys of single or multifamily dwellings to identify weatherization issues. The class covers IR camera operation, and basic report generation, fundamentals of IR science and heat transfer principles. IR Weatherization surveys techniques, tips and tricks, and application examples.

More Information

How does the Lexus Driver Attention Monitor Work?

Here is how Lexus describes their Driver Attention Monitor:

"Mounted on the steering wheel column, a driver-monitor camera is part of the Advanced Pre-Collision System (APCS). It’s designed to recognize when the driver isn’t facing forward. If a frontal collision seems likely and the Driver Attention Monitor senses that the driver is not facing forward, a warning tone will sound, followed by a flashing light. "

While I don't have detailed specifications of the system, I believe that the system employs a near IR camera, working at the same wavelengths as an infrared remote control to view the drivers head. There might be an infrared LED providing illumination for the camera at night.


So I don't think this system is a LW IR camera as is typically used for thermography.

New Web Course: FLIR 600 Series Basics

This course provides an introduction to the operation of all variants of the FLIR 600 series cameras. These include the P620/640/660 and the B620/640/660. You will need to have your camera with you in order to obtain the maximum benefit from the camera operation exercises.

We highly recommend taking this course prior to taking the Thermography Basics, Building IR Basics, Level I, Weatherization, or Building Science courses.

Who should take this course: Users of FLIR 600 series cameras.

Prerequisites: No prior knowledge of thermography or infrared cameras is assumed.

Availability: This course is an on-demand self paced web based training course available 24 hours a day, 7 days a week. You can begin as soon as you enroll.

Link to the course

Inspecting Concrete Block Walls with Thermography

General principles of thermodynamics and heat transfer can be used to explain how voids can be detected by infrared thermography. For most applications, solar energy (sunlight) is permitted to strike the exterior of the wall and heat the surface.

"I have a client who wants me to image a building block wall in search of voids where rebar was incased in concrete as part of the strengthening process. Is there a particular protocol you can point me to that will satisfy the building inspector that no voids exist?"

Solar energy striking the wall is absorbed by the masonry. Hollow or insulated cells create a thermal break or barrier within the cell causing the exterior face shell to heat rapidly. In contrast, the solidly grouted cell acts as a heat sink permitting energy to be conducted through the wall. The emitted energy of the exterior surface is therefore higher in locations of voided cells than that of solid cells. This emitted energy pattern is visible with an infrared camera. This method provides very crisp contrasting data, but is totally dependent on weather conditions and the availability of direct sunlight.

In the daytime, wall sections filled with grout will appear cooler than the other sections. At night, sections with grout will appear warmer than the rest of the wall.

CMU wall section during the day

CMU wall section at night

See these two white papers presented at the InfraMation Conference below:

Use of infrared thermography as a standard in the quality assurance and quality control of grouted masonry construction

Thermographic evaluation of concrete masonry walls: have they been properly reinforced?

Tips to find moisture in wall cavities and insulation

"I'm looking for moisture in wall cavities and insulation, all in the interior of homes. I can't even see the studs let alone the screws."

To find moisture in building materials, the infrared camera must see a temperature difference on the surface being viewed: no temperature difference, no detection. The question is; under what conditions can a temperature difference due to moisture occur?

The most common scenario for moisture detection involves a temperature difference due to the evaporation of water from a surface. When water evaporates, the surface will become cooler. In order to evaporate well, the air dewpoint temperature should be lower than the air temperature, the lower the better.

If the relative humidity where you are trying to inspect is 90%, you are not going to get much evaporation, hence not much cooling, hence very low temperature differences that might not be spotted with your IR camera. In such a situation, use a dehumidifier in the room to lower the humidity (it also adds heat to the room which raises the temperature and also lowers the humidity as well).

Always confirm your readings with a moisture meter.

Wet insulation has a lower R value, or resistance to heat flow compared to dry insulation. So in situations where you have a temperature difference on either side of a wall, the wet insulation would allow heat to flow more easily, hence a thermal indication on the wall. Again, you need a temperature difference between both wall surfaces that has been there for several hours.

Will the wet areas appear hot or cold? That depends on the temperatures on the wall. For instance in the winter, where the inside is warmer than the exterior, you would expect to see a cool area when viewing from the interior. In the summer where the exterior wall temperature is higher than the interior, you would expect to see a warm area from the inside. Again, always confirm with a moisture meter, because there can be other reasons for hot or cold areas as well (like missing insulation, poorly fitted insulation, air leakage, heating ducts, etc.)

EdenPure Heater Thermal Imaging

What do you think of this video? Can you explain the difference in heating after 15 minutes between the conventional heater and the EdenPure? Enter your comments below.

Can IR cameras see through walls?

Here is a question recently asked me by a student.

"I recently purchased the FLIR SD camera and took your training course which had a lot of valuable information but I'm still unsure about a couple of things. Since these cameras are supposed to be so sophisticated, shouldn't you be able to see through the wall to the studs and would this be part of thermal tuning, and I know you talked a little bit about it, but how do you get the camera exactly tuned and focused for the best possible picture?"

These cameras are sophisticated but we are dealing with Infrared, not X-Ray. Your question deals with basic physics and has nothing to do with the cameras themselves. Walls are opaque to infrared imaging cameras. Now you may have seen some movies depicting looking through walls and seeing people inside a room with an infrared camera, this is Hollywood creative hogwash.

What we see with the infrared camera is the infrared heat radiation produced by the surface of the wall based on its temperature and emissivity. The reason we can see studs in the wall, under the right temperature conditions, is due to conductive heat transfer changing the surface temperature of the wall differently over the studs, vs the insulated cavities between studs. This requires a temperature difference on each side of the wall.

The better infrared cameras can detect and image this temperature variation with less of a temperature difference on each side of the wall because they have better thermal sensitivity. A less sensitive camera will require a larger temperature difference in order to get a clear picture. This is one of the areas thermal tuning comes into play, adjusting the temperature span and the temperature level of the picture to bring out the details as best as your camera allows. Most of the time, letting the camera do the work for you in automatic mode works pretty well. But when you have low temperature differences, or there is something very hot or cold in the image that is throwing the auto adjustment off, then you have to switch the camera to manual and thermal tune yourself.

Focusing is most easily performed by finding a sharp corner or line on the target and adjusting your lens until it is a sharp as can be. If you have a surface you are viewing that doesn't have any distinct features, then what I often do is warm up a pencil in my hands, place the point against the surface, and then focus on the pencil point so it is sharp.