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Topic: Non-Contact Thermometers (3 msgs / 79 lines)
1) From: Clifton Burkett
What type of non-contact thermometer are people using? I would like to
measure the temperature of espresso just out of a group head before it =
hits
the cup at the start and stop of an espresso extraction to determine the
thermal stability of a the group head. I am thinking of a getting a
non-contact thermometer to prevent the device from effecting the =
results.
I'd also like to see what the temp is of the beans as they are ejected =
into
the cooling tray in my hottop. Hard to get a standard probe into the =
tray as
it is stirring the beans as it cools them. Anyone out there have any
experience with Raytek Non-Contact Thermometers?  
Thanks
Clif and Odie the Pem - SomeWhere in Florida

2) From: Paul Goelz
At 11:26 PM 2/13/2004, you wrote:
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Non-contact measurement is trickier than you might think if you are looking 
for an accurate measurement.  You have to have set the emissivity of the 
target correctly, the instrument must not be able to "see" anything except 
the target and the measurement spot size has to be smaller than the 
target.  Emissivity may not be a huge problem with food since many organic 
targets are about the same emissivity.  But the spot size is a real 
problem.  All the inexpensive handhelds have a rather large spot.  The spot 
is NOT the same size as the laser spot.  The laser is just an aiming device 
to show you the center of the measurement area, which can be in the area of 
an inch across.
The Raytek handhelds that I have see will give you a rough estimate of the 
temperature but you will have to carefully read the manual to determine the 
spot size and errors due to emissivity.  I am not sure the emissivity can 
be set on the low end Rayteks.
Paul
Paul Goelz
Rochester Hills, MI
paul
pgoelzhttp://www.pgoelz.com

3) From: Ken Mary
I can see a few problems measuring the espresso, the most important being 
the spot size. Minimum spot size for low cost hand held IR thermometers is
about 1/2 inch diameter, so the thermometer will see the stream plus
whatever is in the background and give an incorrect temperature. If you want
to pay more, Fluke has a sensor (model 80T) that plugs into any DMM and
measures a one tenth inch spot, but at very close range.
Measuring bean temperature with IR works fine. Just make sure that the
sensor sees only beans sufficiently deep that the tray is not visible. I do
not use a Raytek, but others in the group may. The Raytek MT4 is ok but
overpriced for its features. A better model is the Tenma part no 72-6748
fromhttp://mcm.newark.com, but there are others of equal or greater value.
Google for best price before you buy.
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