Sciencemadness Discussion Board

high temperature thermometer

soma - 30-6-2016 at 23:42

I'm looking for a high temperature thermometer that can measure 700-1000C. Are there glass thermometers that can do that? Hopefully there's something inexpensive (around $30?)

I want to use it for converting MgCO3 to light burned MgO.

Orenousername - 1-7-2016 at 00:22

Glass is likely to melt at those temperatures, and even if it does not it will be severely weakened. Go with thermocouples, although I suspect you will have a hard time finding one that is rated for those temperatures.

Tsjerk - 1-7-2016 at 00:22

I think you should have a look at an infrared thermometer, I don't think much will survive those temperatures.

Volanschemia - 1-7-2016 at 00:23

Borosilicate glass begins to soften at 820 degrees Celcius, so you definitely wouldn't find boro glass thermometer that can go to 1000.

Quartz glass can go to about 2000 degrees, but I don't know if quartz glass thermometers are very common. I definitely don't think you would get one for $30.

[Edit] Lol, double ninja'd.

[Edited on 1-7-2016 by Volanschemia]

soma - 1-7-2016 at 02:29


I found a company that makes quartz glass thermometers. They're in Germany.

Dr.Bob - 1-7-2016 at 06:30

There are simple metal thermocouple thermometers that go up to that temp which will cost less than anything made of quartz. Just look on Omega, JKem, or other thermocouple sellers for the right type for that temp range.

careysub - 1-7-2016 at 08:05

Use a thermocouple. The common type K is available in models that go to 1260 C. The sensor is cheap and easily replaceable. They respond very quickly to temp changes. Thermocouple thermometers with dual inputs (use two thermocouples at once) are common. They don't break.

A wide variety of probe constructions are available, from a simple junction at the end two wires, to integrated high temperature metal probes. You can use borosilicate glass tube with a thermocouple inside, sealed on one end like a glass thermometer. High alumina mullite tubes for thermocouple protection to the type K max temperature are readily available.

experimenter_ - 1-7-2016 at 13:17

Make a simple thermocouple from two high temperature wires (eg. canthal and nickel wire) and connect it to a voltmeter. Calibrate it patiently with melting points of metals, salts or sth similar.

Not the eaiest to do but the cheapest of all.

careysub - 1-7-2016 at 13:52

You can buy a type K thermocouple on eBay for $1 USD, including shipping.

I doubt very much you buy both a Kanthal and a Nickel wire, however short, for that price.

Using a standard thermocouple allows you to get a thermometer (starting at around $10 on eBay) that directly reads the correct temperature. I cannot imagine that the inconvenience of constantly having to convert volt readings to actual temperature could be worth the savings of a few dollars (if indeed, any savings at all is achievable - you would have to already own the voltmeter).

CharlieA - 1-7-2016 at 17:13

A PID controller + a Type K thermocouple (measures to ca. 1500*C) will only set you back about $30.
Google "thermocouple" for a good explanation of different types of thermocouples.

subsecret - 1-7-2016 at 17:53

In open air, a normal thermocouple with all insulation removed will work just fine above 1000C. Just cut off the fiberglass insulation and spread the wires. Use this if you'll be using some kind of kiln.

soma - 2-7-2016 at 00:29

Thanks to everyone for the information.

I have some supposed MgO that seems to have been exposed to the air for too long and fizzes alot when reacted with ascorbic acid.

I tried putting it in the bottom of a double boiler and covering it with the top of the boiler and heating it on a gas stove for 1/2 hour.

Now it doesn't fizz much but it also reacts very slowly so it seems I hard burned it.

soma - 14-7-2016 at 00:01

I found this temperature controller on ebay for $23. Not sure how to hook up the thermocouple to it. Do they have standard inputs?

[Edited on 14-7-2016 by soma]

Fulmen - 14-7-2016 at 00:46

The wiring schematics should be printed on the side.

soma - 29-7-2016 at 22:44

Found another one that comes with TC probes. Thinking to get the K type.

It also comes with thermocouple K wires. Can these wires be put into the heated material and used instead of the probe?

[Edited on 30-7-2016 by soma]

metalresearcher - 30-7-2016 at 00:24

Ebay is your friend.

I have that device and ot works excellently.

For contact measurement I use type S. I have K ones as well, but don't make them too hot (< 1100 C) otherwise they burn out quickly.
Type S is much more expensive (as it contains Pt), but also much more durable and much hotter (1550 C).