Tamas borat,

All measurement tools for radiant energy are based on two laws: Wien's
and Stefan-Bolzman law. No matter the pyrometer's basic principle or
the sensors used (two waves pyrometers, global radiation pyrometers,
with photodiodes, thermocouples or pyroelectric detectors) all
pirometers in this world are taking care about those two laws.
Unfortunately I don't have any document written in english (only in
romanian and printed) which could explain the corelation between the
surface area radiation, emisivity and temperature. You should guess it
(I think) searching for those two laws. A very short document
describig the laws  (at page 3) is here:
http://www.ucd.ie/geograph/GMills/course.pdf

Well known is that any pyrometer has an emisivity correction mechanism, which
shows the difference betwen the black body radiation and the real
world measured surfaces.
That's why any precise  pyrometer could have a big measurement error
if the emisivity of the probe under test is unknown. Also, if the
probe target is too small, the error could increase (some pyrometers
can't even measure very small targets).

greetings,
Vasile


On 1/24/07, Tamas Rudnai <tamas.rudnai@gmail.com> wrote:
> Thanks for the input. Well, what I need is to measure an iron (200-250 C),
> to measure the temperature of my battery, motor and other stuff just to make
> sure they are operated at the right way or under the specifications or
> whatever. I also was thinking of using such a device if I decide to try out
> that home brew smd soldering stuff mentioned here in another topic.
>
> Actually just bought a cheap one to play and make some experience with it.
> It says it goes up to 280 C. It seems I could not measure shiny surfaces (as
> mentioned by Herbert) and also I have a hot air blow tool but when it is
> operated (so the air is moving out from it) this device measures only 42 C,
> however, when I switch it off it measures the correct (or I believe the
> correct) temperature.
>
> Still in question what about my outrunner motor, where the surface I would
> like to measure continuously rotating and obviously the air around moving?
> And also in question if I'd like to measure the temp of my two stroke engine
> which is vibrating a lot (and also the air screw makes a huge air movement)?
> If this type of measurement does not work for those, what other type can I
> use?
>
> Thanks again answering to my stupid questions :-)
> Tamas
>
>
>
> On 1/24/07, Vasile Surducan <piclist9@gmail.com> wrote:
> >
> > On 1/23/07, Tamas Rudnai <tamas.rudnai@gmail.com> wrote:
> > > Is anybody knows the accuracy of these devices? OK, each says around 1-2
> >
> > Usually I'll say "In your dreams". But because I know you a little
> > bit, you deserve a detailed answer.  If you'll measure a red iron
> > surface comming from a furnance, having say 1800C, how much will means
> > 1-2C as a procentual error ?
> > Does the iron has exactly the same colour over it's surface ?
> > If you're measuring 200C of a hot plate  what does it means 1-2C ?
> > But if you're measuring a cold cup of water (having say 15C) when the
> > ambiant temperature is +30C, what does it mean 1-2C ?
> >
> > I think you've got the essence.
> > greetings,
> > Vasile
> >
> > P.S. Do not believe any infrared thermometer builder specifications
> > (without understanding how was specified) even if it's Raytek or other
> > great name.
> >
> >
> > > Celsius, however, I am not sure if that is true for all type of
> > surfaces?
> > > Also how the accuracy affected by wind, humidity and vibration?
> > >
> > > Thanks,
> > > Tamas
> > >
> > >
> > > --
> > > unPIC -- The PIC Disassembler
> > > http://unpic.sourceforge.net
> > > --
> > > http://www.piclist.com PIC/SX FAQ & list archive
> > > View/change your membership options at
> > > http://mailman.mit.edu/mailman/listinfo/piclist
> > >
> > --
> > http://www.piclist.com PIC/SX FAQ & list archive
> > View/change your membership options at
> > http://mailman.mit.edu/mailman/listinfo/piclist
> >
>
>
>
> --
> unPIC -- The PIC Disassembler
> http://unpic.sourceforge.net
> --
> http://www.piclist.com PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist