# Thermography QOD 10-06-2008

Let’s start off with something relatively easy.

It is the temperature scale that actually falls on zero.

Kevin

All Thermographer’s should know this answer. If not, you need to go back to your books.

this was a good show/dvd, i’ll let others reply with answer…although an ex-wife comes to mind

I used to know a kid named Kelvin C. Farhrenheit.

Cool stuff to look forward to on a Monday.

Thanks Kevin

Mic

No worries…they will get harder

Kevin

Hi to all,

I’d like to thank Kevin for offering to help out with the QOD series and I look forward to many more IR related questions.

Thanks Kevin

Regards

Gerry

How about expanding this question to: “which temperature scales utilizes the same temperature difference”?

Celsius - Rankine
Fahrenheit - Celsius
Celsius - Kelvin
Kelvin - Fahrenheit
Rankine - Kelvin

Easy does it, David. We don’t want give people brain cramps here

We’re going to start slow and work our way up to the more difficult questions.

Your question above seems a bit misleading. What do you mean by “Temperature Difference”?

Absolute zero can be defined as either 0 K or 0 R.

Kelvin is equal to −273.15° on the Celsius scale
Rankine is equal to −459.67° on the Fahrenheit scale

Kevin

And here I thought it was when you were out of Vodka.

Thanks for starting off the IR questions on the easy side Kevin.

That is the difference in degrees you add to each scale to obtain a known temperature rise or delta.

If you have 100 degrees F (37.8 degrees C) and you add 50 degrees F, what is the degree rise in C?

A 50F rise = 27.7C.

Not that you need to know any of this in my question.

A 100 degree rise in Celsius or Kelvin is the same as a 180 degree rise in Fahrenheit or Rankine.

So the answer to the question is Celsius - Kelvin.

What does this matter?
Delta temps are sometimes listed in K. If they are talking about a 20 degree delta K, you know it is the same as a 20 degree delta C.
Even though the temp value between K & C is 273 degrees different.
Beleive it or not, I came across this last week and I had to think about it.

Seeing everyone did so well, I figured food for thought would tide them over till next week!

Starting to sound like an Electrician David.:mrgreen:

Sorry Brian! (and others)!

David I hope you know me better than that, no appologies necessary.

Dammed if even kicking and screaming I don’t learn something from your posts. :mrgreen:

David,

But, your question is still misleading. What you are referring to is temperature “conversion.”

The true answer to your question is Celsius - Kelvin and Kelvin - Celsius and Fahrenheit - Rankine and Rankine - Fahrenheit

Formulae:

Celsius to Kelvin
°C + 273.15 = °K

Kelvin to Celsius
°K - 273.15 = °C

Fahrenheit to Rankine
°F + 459.69 = °R

Rankine to Fahrenheit
°R - 459.69 = °F

If you are converting Delta-T, then there is no change between °F and °R and °C and °K, as you have already indicated.

However, if you are converting °C to °F or °K to °R, then it would be x1.8 or +1.8.

It confused the crap out of me when I was first introduced to temperature conversions in Level II.

Kevin

I know.
I was very confused as well!
That was the point. Just to think about it.
You don’t need to know all the math, just understand a little about what it is all about.

Let me tell you, I have been called out on the carpet in front of several experts that know more than I. When you can convert K to C and explain it’s relevance to F they will get confused as well. If your close or right, all discussion ceases. Just presenting yourself as understanding a little more than most is unreal!

I’m not trying to test anyone’s knowledge, just expose them to something that may save their hide sometime.