Questions of the Week 05/13/2018

**Welcome to another round of Questions of The Week !
**

Questions of the week:

Introduction and requirements:

A member of the Award Committee will post a question, at a random day/time.

A competing member may make one post per question thread to answer the questions and the member’s winning entry must have all parts of the questions answered completely in that one post. Editing your one answer post allowed will result in disqualification.

Winnings will be limited to no more than 6 times in a given year, the objective is to allow as many Members a chance to win as possible.
Any disregard to the above and divulging the correct answers will forfeit the weekly winnings.

So please refrain from participating if you have already won in the maximum for the Year.

First correct answer (as judged by the Awards Committee or Poster of the Question) wins.

The lucky winner will get a case of “Now that you’ve had a Home Inspection Books” shipped to them at their address on file. Make sure your Address on File with Inachi is correct.

Winners of the Question of The Week shall request their prize by emailing fastreply@nachi.org and submitting their Mailing address for shipping.

Allow 2 weeks for delivery.

**THANKS for playing and good luck! ** :smile:

This week’s questions relate to infrared theory and its practical effect on infrared thermography. The “focus” today is on emissivity.

Thermal emittance or thermal emissivity is the measure of how well an object radiates infrared energy compared to a standard black body. It’s an important consideration in many infrared thermography applications.

  1. A solid object that is opaque to infrared radiation and is a good reflector of infrared radiation will be a _____ emitter of infrared radiation.

A. strong
B. poor
C. unpredictable based on information provided… (explain)

  1. Ordinary glass is opaque to infrared radiation.

True
False
It depends… (explain)

  1. The emissivity of an object may be affected by (identify all that are FALSE).

A. the surface smoothness of the object
B. the shape of the object
C. the angle at which the object is viewed
D. the temperature of the object
E. the color of the object
F. the IR wavelength

  1. If you plug the appropriate emissivity of an object into your infrared imager, it will give you an accurate representation of the actual temperature of that object.

True
False

  1. Decreasing the emittance value of your imager will cause the observed temperature to go ____

Up
Down
It depends… (explain)

Bonus question (the prize is bragging rights): How do Low-E windows for hot climates differ from Low-E windows for cold climates and why?

:slight_smile: .:cool:

1-B
2- True
3-D
4-F
5- Up

Where are all the “Flir One, C2, and C3” users?

Eye nose wee gotz uh lott ov 'em hair!

Hopefully all these I R guys will show up.

This stuff is way beyond my roof. :slight_smile:

  1. B
  2. True
  3. E
  4. False
  5. Up

B
T
E
F
It depends, objects with high reflectivity can reflect energy radiated by other objects, making your emissivity setting moot.

No one has topped 60% so far.

Let’s get some more challengers. I know we have plenty of infrared practitioners.

Come on Charley, throw your red hat into the ring…and some of you other infrared thermographers out there, too. We all need to learn from the more advanced. :smiley:

I sent a little reminder to Charley for him to join in, but he is a busy man. ;):slight_smile:

B
T
D
T
C Different materials have different charecteristics

A. strong

  1. Ordinary glass is opaque to infrared radiation.
    True

  2. The emissivity of an object may be affected by (identify all that are FALSE).
    F. the IR wavelength

  3. If you plug the appropriate emissivity of an object into your infrared imager, it will give you an accurate representation of the actual temperature of that object.

False

  1. Decreasing the emittance value of your imager will cause the observed temperature to go ____

It depends… Reflectivity of the object you are imaging could cause all sorts of whacky readings. Ideally the temperature will go down, but as shown in question 3 lots of things affect how IR cameras read different object.

Bonus question (the prize is bragging rights): How do Low-E windows for hot climates differ from Low-E windows for cold climates and why?

I have absolutely no idea, but my guess is that the gas injected in between the panes are different. A lower energy gas in hot climates so when it gets hot it moves around more, helping deflect more radiation. Higher energy gas in cold climates so that it bounces around more when its cold and does the same. But I have no clue.

I have absolutely no idea, but my guess is that the gas injected in between the panes are different. A lower energy gas in hot climates so when it gets hot it moves around more, helping deflect more radiation. Higher energy gas in cold climates so that it bounces around more when its cold and does the same. But I have no clue.

Sounds good to me. ;):slight_smile:

I’ll give it a shot.

  1. B
  2. True - But, still emits IR on the surface without reflections
  3. B, E
  4. True
  5. Up

Bonus: Low E coatings should be arranged on the panes to reflect IR toward the inside of the home in colder climates, and toward the outside in warm climates.

Perhaps a couple of thermal images provided by our colleague, Scott Gilligan will help with one of the questions that seems to have stumped everyone so far.

https://www.nachi.org/forum/attachment.php?attachmentid=45048&d=1306518435

https://www.nachi.org/forum/attachment.php?attachmentid=45049&d=1306518460

I’ll throw in a hint: The infrared spectrum is very large and includes many different wavelengths. The behavior of infrared at the shorter end of the spectrum can be very different than the behavior of the longer wavelengths. Though we are all very familiar with imagers that detect long wave infrared radiation there are imagers that detect short and mid-wave radiation too.

Any lights turn on?

After consulting with the judges on this, they have agreed to accept your answer to the bonus question (technically, the coatings reduce the emission of heat in the form of infrared radiation)

Congratulation! You’ve earned bragging rights on the Bonus Question.

In very hot climates, the Low-E the coating should be on surface #2 (reducing the ability of the outer glass to radiate heat into the structure across the space between the panes). In very cold climates, it goes on surface #3 (reducing the ability of the inner pane to radiate heat out of the structure across the space between the panes).

Surfaces are numbered from the outside in: The outside surface of outside pane is #1; The inside surface of outside pane is #2; The outside surface of the inside pane is #3; the inside surface of the inside pane is #4.

Good questions Chuck. I do plan on taking a level 2 class, so I can answer essay questions.:cool:

Congratulations Brad. :slight_smile:

YEA Brad!
Must be da T-Shirt. :mrgreen:

Great questions Chuck, thanks for your time. Congrats Brad!