Thermocouple max. temperature rating? - Page 1
Forum section: electronics / testgear

author: lpc32
author_rank: Frequent Contributor
timestamp: March 12, 2014, 04:34:14 pm
content: I have a flimsy looking type K thermocouple, roughly similar to this:The black tubing near the tip is labeled 125°C. Should this thing be suitable for measuring 400-500C with direct contact?

author: dfmischler
author_rank: Frequent Contributor
timestamp: March 12, 2014, 04:37:49 pm
content: It isType K. Do you have the manufacturer's specifications? What do they say?

author: Rigby
author_rank: Super Contributor
timestamp: March 12, 2014, 05:28:55 pm
content: Not all Type Ks are the same. The specsheet for the thermocouple you bought will tell you the min/max ratings. The 125C on the black shrink tube is probably for the shrink tube only.

author: lpc32
author_rank: Frequent Contributor
timestamp: March 12, 2014, 06:11:59 pm
content: The DMM it came with is specced for much higher. No separate specs for the probe.Yeah, the 125C is for the tube. But doesn't that imply something about the manufacturer's expected maximum temperature for the whole probe? After all, that tube is almost on the tip.

author: Electric flower
author_rank: Regular Contributor
timestamp: March 12, 2014, 07:06:53 pm
content: With simmilar thermocouple i managed to get reading od ~800 celsius degrees while heating it with lighter, tip of thermocopule was glowing orange... i was watching out to not light up the shrink tubink, once i tryed to see how durable heatshrink tubing is at temperatures about 400-500 degrees C, heatshrink tube got on flame and it was the worst smell ever.Still, thermocouple is working fine.Edit: i guess you could use it but be carefull becouse things can get messy (and smelly) if you screw up. I have also put a picture of what my tip looks like, sorry i don't have better camera

author: N2IXK
author_rank: Frequent Contributor
timestamp: March 13, 2014, 12:00:18 am
content: A type K bare wire thermocouple (the Chromel/Alumel wires themselves) is good to over 1200C. Most types of insulation are less heat resistant, and are the limiting factor for any particular TC probe assembly.You really need to get the manufacturer's datasheet for your particular probe.

author: lpc32
author_rank: Frequent Contributor
timestamp: March 13, 2014, 09:37:31 pm
content: It's unclear why they add the tubing, then.And actually I was wrong, there are specs for the probe, sort of. If I understand the manual correctly (Chinese company, borderline English), the probe is up to 230C. Looking at similar probes on eBay, some claim to be up to 300C, others up to 700C. Random numbers, I guess?What about the following type of probes? Is it better suited for high temperatures? Again, eBay sellers list random numbers for similar probes; anything from 300C up to 1200C.

author: N2IXK
author_rank: Frequent Contributor
timestamp: March 13, 2014, 11:34:28 pm
content: Can't tell you anything from a picture. Who knows what is inside that probe. Internal wire insulation may melt, or the probe will conduct enough heat to melt the plastic handle or leadwires.If you need guaranteed specs, you need to buy from a proper vendor, or be prepared to sacrifice a few cheapies in testing.

author: hamster_nz
author_rank: Super Contributor
timestamp: March 13, 2014, 11:45:26 pm
content: CHeck outhttp://www.adafruit.com/products/270- it has glass and is good to 500C.I use this part in my reflow oven.

author: lpc32
author_rank: Frequent Contributor
timestamp: March 18, 2014, 01:15:00 am
content: Shrink tubing included?

author: RobertHolcombe
author_rank: Frequent Contributor
timestamp: March 18, 2014, 02:37:44 am
content: Quote from: lpc32 on March 18, 2014, 01:15:00 am"There's a small piece of heat shrink on the end to keep the fiberglass from fraying. If you're using at >250°C temperatures, simply remove it with a small blade."

author: lpc32
author_rank: Frequent Contributor
timestamp: March 18, 2014, 04:18:27 am
content: Hah. That's quaint.