| Products > Test Equipment |
| 121GW Thermocouple Question |
| << < (3/3) |
| J-R:
Found some photos here of a UEi bead thermocouple where it seems to suggest any tubing is not for keeping the ends from fraying. In one photo it's not in the right position, and in the other it's not there at all: https://www.grainger.com/product/UEI-TEST-INSTRUMENTS-Bead-Wire-Temperature-Probe-6CMU0 Then also an interesting photo showing the tubing being used as protection while the end is clamped. Perhaps the type manufactured for the 121GW is also used in other configurations and they didn't want to bother changing things. |
| JDW:
--- Quote from: J-R on January 31, 2023, 08:15:35 am ---Found some photos here of a UEi bead thermocouple where it seems to suggest any tubing is not for keeping the ends from fraying. In one photo it's not in the right position, and in the other it's not there at all: https://www.grainger.com/product/UEI-TEST-INSTRUMENTS-Bead-Wire-Temperature-Probe-6CMU0 Then also an interesting photo showing the tubing being used as protection while the end is clamped. Perhaps the type manufactured for the 121GW is also used in other configurations and they didn't want to bother changing things. --- End quote --- Sorry to jump back into this thread, but I'm doing thermal testing today. The UEI ATT29 you linked isn't the exact shape of the Type-K thermocouple that came with my 121GW, so I am wondering of what comes with the 121GW has the same maximum temperature spec or something else? That ATT29 says it can measure up to 510°C (and the 121GW meter can measure higher still). But is that correct? I know for a fact that my Fluke's Type-K thermocouple (photo posted earlier in this thread), can only measure a measly -40 to 260ºC. When coupled to a Fluke 116 and placed on a Hakko soldering iron tip set to 350°C, it measures about 270°C, which shows the limits of what that Fluke Type-K thermocouple can measure. I also have a UNI-T UTi260B Thermal Imager (set to Low Gain to measure temps above 150°C), but I really don't know the correct Emissivity setting for soldering iron tips. That is why I was hoping to do a check with a Type-K so as to choose the best Emissivity setting on the thermal imager. So to repeat my question, is the Type-K thermocouple included with the 121GW really able to measure up to 510°C? I wish this important info was printed in the 121GW manual! But I can only find what the meter is capable of (a max of 1350°C), not the max temp. of the included Type-K thermocouple. |
| thm_w:
--- Quote from: JDW on April 27, 2023, 08:24:41 am ---When coupled to a Fluke 116 and placed on a Hakko soldering iron tip set to 350°C, it measures about 270°C, which shows the limits of what that Fluke Type-K thermocouple can measure. --- End quote --- It wasn't making good enough contact with the thermocouple. Its not easy to do, you'll need a very large blob of solder and a wider tip. The temperature limitations of a type K, below 1200°C, are generally due to the insulation used and its lower maximum temperature. You can find similarly designed thermocouples with fiberglass insulation rated for around 400C. |
| JDW:
--- Quote from: thm_w on April 28, 2023, 12:10:50 am --- --- Quote from: JDW on April 27, 2023, 08:24:41 am ---When coupled to a Fluke 116 and placed on a Hakko soldering iron tip set to 350°C, it measures about 270°C, which shows the limits of what that Fluke Type-K thermocouple can measure. --- End quote --- It wasn't making good enough contact with the thermocouple. Its not easy to do, you'll need a very large blob of solder and a wider tip. The temperature limitations of a type K, below 1200°C, are generally due to the insulation used and its lower maximum temperature. You can find similarly designed thermocouples with fiberglass insulation rated for around 400C. --- End quote --- When I used a larger tip and applied a large solder blob, I was then able to get between 348°C and 349°C on both Type-K thermocouples on both my 121GW and Fluke 116 meters. Thanks. But getting a thermal imager to properly read is truly challenging. It seems that the darkness of the object matters quite a bit. I have to set Emissivity to 0.46 to measure roughly 349°C on the solder blob, but that measurement changes as more black cruft appears on the solder blob. And further down the neck, it reads over 400°C, which of course is not right, but such is due to the tip being shinier and lower down the neck being a medium to dark gray. Interesting. My main intent is to measure heat across components on a PCB, most of them being thru-hole -- large 5W resistors, massive electrolytic caps, etc. It's not practical to have multiple meters and multiple Type-K connections, which is why my intent is to take a wire-tie and strap my Type-K to a given 5W resistor to measure it's temperature, then adjust my thermal imager's emissivity to match. Then hopefully, I can get meaningful thermal measurements on other components on the board when it is powered. |
| Overspeed:
Hello So to repeat my question, is the Type-K thermocouple included with the 121GW really able to measure up to 510°C? Any K thermocouple can measure up to 1370 deg C but in the real word that limited to 800 deg C as the alloy used in K thermocouple go oxided over 800 deg C BUT the acquisition circuit can limit this as low cost circuit don t have linearization circuit as K output voltage is not linear https://www.analog.com/en/app-notes/an-1087.html Regards OS |
| Navigation |
| Message Index |
| Previous page |