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anybody use infrared thermometers to check car?



 
 
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  #1  
Old December 8th 10, 02:30 AM posted to rec.autos.tech
ED
external usenet poster
 
Posts: 13
Default anybody use infrared thermometers to check car?


"George Orwell" > wrote in message
...
>I took my car to radiator service, and they had one of
> those infra-red remote thermometers with laser sights.
> So they could measure the temperature of the bottom
> radiator hose, transmission oil cooler and all sorts of
> stuff. I thought of getting one. It seems the good ones
> (with accuracy of 0.75 Celsius) are about $200.
> Any DIY car enthusiasts got one in their back shed?
>

I just picked up one of these units. I couldn't resist the sale at $19.
Lots of uses around the house at this time of the year in finding
air leaks, and checking out the cooling system on the old car.
Can anyone shed some light on the theory behind what makes
it work. I know that it measures the electromagnetic radiation coming
from the surface aimed at to determine the temperature. I don't
see how it works when the object surface is made of wood.
Any takers?


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  #2  
Old December 8th 10, 03:31 AM posted to rec.autos.tech
jim beam[_4_]
external usenet poster
 
Posts: 3,204
Default anybody use infrared thermometers to check car?

On 12/07/2010 05:30 PM, ED wrote:
> "George > wrote in message
> ...
>> I took my car to radiator service, and they had one of
>> those infra-red remote thermometers with laser sights.
>> So they could measure the temperature of the bottom
>> radiator hose, transmission oil cooler and all sorts of
>> stuff. I thought of getting one. It seems the good ones
>> (with accuracy of 0.75 Celsius) are about $200.
>> Any DIY car enthusiasts got one in their back shed?
>>

> I just picked up one of these units. I couldn't resist the sale at $19.
> Lots of uses around the house at this time of the year in finding
> air leaks, and checking out the cooling system on the old car.
> Can anyone shed some light on the theory behind what makes
> it work. I know that it measures the electromagnetic radiation coming
> from the surface aimed at to determine the temperature. I don't
> see how it works when the object surface is made of wood.
> Any takers?


wood is not a good conductor, hence it's temperature to the touch always
seems different from surroundings, but it'll be at ambient temperature
if left alone, and thus emit radiation just the same as everything else.

the unit's sensor is just a "single pixel" sensor like those listed he

http://en.wikipedia.org/wiki/Thermographic_camera

that does math based on black body radiation.

http://en.wikipedia.org/wiki/Blackbody_radiation

the higher the temperature, the shorter the wavelength emitted.

presumably your reader assumes fixed emissivity. if so, this might help
you get more accurate readings:

http://www.raytek.com/Raytek/en-r0/I...Emissivity.htm


--
nomina rutrum rutrum
  #3  
Old December 8th 10, 03:51 AM posted to rec.autos.tech
Pete C.
external usenet poster
 
Posts: 458
Default anybody use infrared thermometers to check car?


ED wrote:
>
> "George Orwell" > wrote in message
> ...
> >I took my car to radiator service, and they had one of
> > those infra-red remote thermometers with laser sights.
> > So they could measure the temperature of the bottom
> > radiator hose, transmission oil cooler and all sorts of
> > stuff. I thought of getting one. It seems the good ones
> > (with accuracy of 0.75 Celsius) are about $200.
> > Any DIY car enthusiasts got one in their back shed?
> >

> I just picked up one of these units. I couldn't resist the sale at $19.
> Lots of uses around the house at this time of the year in finding
> air leaks, and checking out the cooling system on the old car.
> Can anyone shed some light on the theory behind what makes
> it work. I know that it measures the electromagnetic radiation coming
> from the surface aimed at to determine the temperature. I don't
> see how it works when the object surface is made of wood.
> Any takers?


Those IR thermometers are particularly good for quick tire temp checks
when stopping for fuel on a long tow. They are also quite useful in the
kitchen for the many applications where the surface temperature is
sufficient, such as stirred liquids, and unlike probe thermometers they
don't require cleaning after use.
  #4  
Old December 8th 10, 04:36 AM posted to rec.autos.tech
ED
external usenet poster
 
Posts: 13
Default anybody use infrared thermometers to check car?

>
> wood is not a good conductor, hence it's temperature to the touch always
> seems different from surroundings, but it'll be at ambient temperature if
> left alone, and thus emit radiation just the same as everything else.
>
> the unit's sensor is just a "single pixel" sensor like those listed he
>
> http://en.wikipedia.org/wiki/Thermographic_camera
>
> that does math based on black body radiation.
>
> http://en.wikipedia.org/wiki/Blackbody_radiation
>
> the higher the temperature, the shorter the wavelength emitted.
>
> presumably your reader assumes fixed emissivity. if so, this might help
> you get more accurate readings:
>
> http://www.raytek.com/Raytek/en-r0/I...Emissivity.htm
>
>
> --

Solid info. Just what I was looking for. My search of Wiki was lousy.
Thanks a bunch.


 




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