hodges
National Hazard
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Measuring Temperature for Small Amounts of Substance
I wish to measure temperatures at which various substances melt and boil. However, I wish to stick to using small amounts (a few ml in a test tube).
Can anyone thing of a good way of doing this? The temperature range would be say -20C to 200C. I know there are lab themometers that cover this
range, but all the ones I have seen are huge and need to be immersed in at least several inches of liquid.
Thanks,
Hodges
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Elawr
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maybe thermistors?... Simple diodes as well can measure temp, iirc. These components can be very tiny, and are easily encapsulated for immersion into
liquids.
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12AX7
Post Harlot
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Small thermocouple (with suitable meter and/or amplifier to make use of the small voltage) could do it, too.
Electronics professionals I know have spoken of invisibly sized temp sensors, thermistor or otherwise. Size isn't an issue!
Tim
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Twospoons
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I agree with 12AX7 - the sensing tip on a thermocouple is usually only 1-2 mm in diameter, and the wire is only 1.5mm diameter. And thermocouples
are very cheap and easy to buy.
Helicopter: "helico" -> spiral, "pter" -> with wings
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hodges
National Hazard
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Almost all the thermisters I have seen are only good up to 125C. A thermocouple is good up to flame temperatures, but the output is only something
like 40uV per degree C so I would need to build an amplifier or dedicated circuit to use this.
Hodges
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hinz
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Look here:
http://www.omega.de/produkt/t2/unsheat.html
There are NiCr thermocouples with a diameter of 0,01mm for 46 Euro, a bit expensive but the next thicker one is cheaper.
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hodges
National Hazard
Posts: 525
Registered: 17-12-2003
Location: Midwest
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Thanks guys. I think I found something that is going to work, for a reasonable price ($25 on EBay):
Offered here is a digital hi temperature probe thermometer. This instrument delivers a very wide temperature range. It is ideal for monitoring the
temperature in the lab, greenhouse and a variety of industrial applications.
Features
Water Proof
On / Off Switch
°C / °F Switch
Data Hold
Polycarbonate Case
Stainless Steel Probe
Auto power off
Specifications:
Range
-58° to 536°F
-50° to 280°C
Accuracy
±2°F / ±1°C
Resolution
0.1°
Probe Length:
Diameter:
Overall:
5.0" / 12.7 cm
0.137" / 3.5 mm
8.0" / 20.3 cm
Sampling Time
0.5 second
Power Source:
1 "LR44" battery
Battery Life:
5000 hours
Supplied with
Battery
Sheath with Pocket Clip
Hodges
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Texium
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Thread Moved
19-11-2023 at 11:15 |
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