Question 1

Would this work for a forge?  I presume the wires would not survive flames though?

Accepted Answer

They make ceramic insulators with two holes that slide down the wires. We use them on reheat furnaces in the steel industry. You need a screw in thermocouple long enough to go past the insulation. Your wires will be outside. This is assuming you don’t have a coal forge and bellows. If your 1830s blacksmith forget new tech and eyeball the color.

Question 2

How do you turn off auto power off? The instructions are unclear.

Accepted Answer

Press the HOLD button and then press the POWER button

Question 3

Will device read to 2000 F? I have the appropriate K type thermocouple for a foundry furnace (proper insulators, wire, mounting blocks).

Accepted Answer

It will read everything within the range. I can't remember the range.

Question 4

Can you manually calibrate this using ice water and boiling water?

Accepted Answer

Interesting idea, calibrating an instrument that can use a bunch of different alloy TCs.

I suppose one might expect to calibrate the basic A/D conversion portion of the circuit, and perhaps a portion of the cold junction compensation, depending on how that’s designed; there are commercial ICs that do the job, but they depend on careful design of the chip placement and board design, and all of ‘em that we’ve used over the years are specific to a single type, J or K or whatever.

Calibration of the rest of the design, specifically the portion that interprets the input from the TC and generates a number that can be displayed, that’s a whole ‘nother ballgame - the NIST tables are a glory to be seen, and AFAIK there is no reason to ever expect to tweak the 7 (or 9 or 11 or more) degree polynomials that describe a pristine alloy junction in a perfectly designed and constructed circuit.

If the firmware is set up to allow tweaks of this sort (we’ve seen some badly intentioned equipment that does just that) you’re going to be out of luck - any procedure within reach of the ordinary well intentioned consumer is doomed to failure.

An ice bath and boiling water is a good example; the minimum lab grade equipment needed, triple point cells and such, isn’t easy to obtain or use, and calibration over small T ranges isn’t useful in the general sense.

When we were doing a precision design, we had access to triple point cells with carefully chosen metallic alloys, and could check calibration of (for example) a shipment of type J or K extension cable over ranges of several hundred degrees C.

It was a PITA, too; the interesting stuff we did used precision platinum RTDs from NIST (actually, originally from NBS around 1950 that cost several thousand $ each back then) with which we were able to calibrate our calibration equipment to 0.001 degrees C.

All that got us with the equipment under design was the ability to guarantee that any two examples anywhere in the world would agree within 0.1 degree C over the three month calibration cycle.

Measuring temperature precisely and accurately to a known standard spec is a lot harder than it seems like it ought to be, until you sit down an try to prove that what the display says is actually correct.

Consider this piece of equipment to be useful to plus or minus several degrees F or C, take your pick, and you’ll be fine. For most uses, that plenty good enough.

(For medicine use a mercury fever thermometer, and enjoy the precision that an extremely limited range can get you at a fairly low price. But what does it mean? That’s a different issue, eh? Even the newer electronic fever thermometers are good enough, really. But the mercury ones are really, really good instruments, a rarity in temperature measurement that’s under appreciated…)

LeatonDigital Thermocouple Thermometer Dual-Channel LCD Backlight Temperature Meter Tester for K/J/T/E/R/S/N Great

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