metalresearcher
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Infrared thermometer to 1600oC : some experiences ?
On ebay I found this thermometer
http://shop.ebay.com/i.html?_dlg=1&_jgr=1&LH_PrefLoc...
It covers the whole temperature range up till iron casting.
Seems interesting for contactless temperature measuring without the hassle of destroying a thermocouple by dipping it into a molten metal bath. Does
anybody have experience with such a high temp one ?
Normally these thermometers go up to 300-500oC I have one (also from eBay, but different seller) which measures up to 550oC and is remarkably good for
the price ($43).
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PHILOU Zrealone
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I have used such a contactless thermometer with laser.
In my case it was a -20°C to 500°C with 0.1°C precision between -20°C and 50°C; 0.5°C between 50 and 150°C and 1°C above. We used to measure
samples between -5°C and 35°C.
It is efficient but it depends on the reflection of the surface you are measuring (glass, soil, metal) and so angle of measurement is important too.
For the rest check for calibration from time to time with known compounds melting points.
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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watson.fawkes
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Quote: Originally posted by PHILOU Zrealone  | It is efficient but it depends on the reflection of the surface you are measuring (glass, soil, metal) and so angle of measurement is important too.
For the rest check for calibration from time to time with known compounds melting points. |
There are two ways
to build a infrared thermometer: intensity of a signal or spectroscopy on a signal. I can't say which measuring technique the device in question uses.
A spectroscopic device is far less prone to reflectivity and ambient light than an intensity-based one. The recommendation to calibrate is well-given.
Apropos of this subject, I've been meaning to build a spectroscopic version of this. I acquired an optical train (an old 35mm film camera, Nikon) a
while back at a thrift store. I've been desultorily looking for a retail source of blazed diffraction gratings for the near-IR/visible range, that is,
a vendor that will sell single units by mail order with posted prices. Any leads? All the ones I seem to find want to do quotes and get to know me; I
don't want to spend the time on all that.
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Intergalactic_Captain
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PHILOU - From the sounds of it you've got the same one I do - the Centech model from Harbor Freight? If so, as long as the battery's fresh it's a
rather reliable unit at a steal of a price. AFAIK, it's simply an intensity-based unit that uses an IR-pass lens and some sort of photodiode or
photoresistor.
The only advice I can give is that before you NEED to use it, play around with it and hone your technique. These things are not really designed for
close-up (under several feet) use, and the spot from the laser is quite far from what the lens is seeing at a <2' range. For example, when my
stainless-probe digital thermometer (that somehow withstood EVERYTHING except a nitration runaway) died, the centech was my only thermometer - I was
running a reaction and realized that with a 500mL RBF, if the laser spot was on the neck, it essentially read the vapor temperature. If it was in the
headspace, it read the solution temperature. If it was on the solution, it read the bath temperature. If it was on the base of the pot, it read the
heating element temperature...
...You get the idea - They can be quite reliable once you know how to use them properly, and are incredibly useful in taking instant readings where no
other thermometers can - Hell, I can see in "x-ray vision" how my hotplate is wound by the hotspots in the oil bath. Been meaning to pick up
something with a higher range, but the prices are too steep - That would be a nailbiter for me if the base price was in USD instead of GBP...
If you see me running, try to keep up.
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smuv
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I tried using an IR thermometer on stainless steel, it said the piece was 60c when in reality it was over 200c. I wouldn't rely on it unless you
calibrate to be sure the readings are ok.
"Titanium tetrachloride…You sly temptress." --Walter Bishop
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Magpie
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| Quote: Originally posted by smuv | | I tried using an IR thermometer on stainless steel, it said the piece was 60c when in reality it was over 200c. |
Did your instrument have a compensation for the material's emissivity? IIRC correctly SS has an e ~ 0.6.
The single most important condition for a successful synthesis is good mixing - Nicodem
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Texium
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