Analog pyrometer wiring?

[Msheffield]

Hi you all, I recently purchased a 2" analog pyrometer from Clay King, and also purchased a K-type thermocouple which was listed alongside it as compatible. When I received it, I noticed that the wire was the plug type that is used with digital pyrometers, so I am wondering if I can snip the plug off and wire it directly to the the pyrometer/thermocouple so that it is the same as the end with the two wires. Any thoughts? 

[Mark C.]

No need two cut wires as that plug comes apart with screws as I can see in photo-you can cut it if needed but a small screwdriver will work without cutting.

[neilestrick]

What Mark said.

[Msheffield]

54 minutes ago, Mark C. said:

No need two cut wires as that plug comes apart with screws as I can see in photo-you can cut it if needed but a small screwdriver will work without cutting.

Awesome, thank you! I didn't notice the screws. 

[Dick White]

Just remember that the yellow wire goes to the + terminal and the red wire goes to the - terminal.

[Bill Kielb]

Just a caution, if that is not a heavy gauge thermocouple (8 gauge) and it is a rather thin gauge as many of the type k’s with their own lead wire often are, the probe may not last long for kiln service.  No worries though always can replace with a heavier 8 gauge probe and holder then run tcouple wire to your meter. Your meter will work fine with any type K tcouple.

[Msheffield]

17 hours ago, Dick White said:

Just remember that the yellow wire goes to the + terminal and the red wire goes to the - terminal.

Thanks for the reminder!

[Msheffield]

17 hours ago, Bill Kielb said:

Just a caution, if that is not a heavy gauge thermocouple (8 gauge) and it is a rather thin gauge as many of the type k’s with their own lead wire often are, the probe may not last long for kiln service.  No worries though always can replace with a heavier 8 gauge probe and holder then run tcouple wire to your meter. Your meter will work fine with any type K tcouple.

Interesting.... and good to know. I will look up the thermocouple type and see. 

[Bill Kielb]

Hey looking at your gallery photos it appears you have a 14 gauge tcouple. It will not last as long as an 8 gauge but should be fine.

[Msheffield]

5 hours ago, Bill Kielb said:

Hey looking at your gallery photos it appears you have a 14 gauge tcouple. It will not last as long as an 8 gauge but should be fine.

Cool. How long do they typically last, in your experience? 

[Bill Kielb]

Depending on your use, if you leave it in for the entire firing as opposed to using it to spot check, 100-300  firings is typical, with the 8 gauge heavier style probably 100 firings more. The bisque firings damage them significantly with corrosive vapors. So depending on clay body etc. with full firing measurement I have replaced the non protected (bare) style heavy gauge  in as few as 150 firings. Several hundred is typical and the heavy 8 gauge definitely lasts 20-50% longer.

chart below shows gauge recommendations for various types. Type K,  8 gauge generally for 2300  f

 

[Mark C.]

you can buy a digital pyrometer for very cheap nowdays and they are so much better than that analog gauge -Bill has a ling to cheap ones if I recall for under $50 on Amazon . You need the plug for those.

[Msheffield]

6 hours ago, Bill Kielb said:

Depending on your use, if you leave it in for the entire firing as opposed to using it to spot check, 100-300  firings is typical, with the 8 gauge heavier style probably 100 firings more. The bisque firings damage them significantly with corrosive vapors. So depending on clay body etc. with full firing measurement I have replaced the non protected (bare) style heavy gauge  in as few as 150 firings. Several hundred is typical and the heavy 8 gauge definitely lasts 20-50% longer.

chart below shows gauge recommendations for various types. Type K,  8 gauge generally for 2300  f

 

Oh, that doesn't seem terrible! Maybe similar to element life, if not longer? 

[Msheffield]

5 hours ago, Mark C. said:

you can buy a digital pyrometer for very cheap nowdays and they are so much better than that analog gauge -Bill has a ling to cheap ones if I recall for under $50 on Amazon . You need the plug for those.

I will do that eventually for sure. I was trying to save money is why, but I should probably just go for it. Can't seem to get my analog one working, though I double-checked the wiring three times. I'll post photos tomorrow and see if I'm doing something wrong. 

[Bill Kielb]

Just change the polarity and see if the meter works. Not all tcouple markings follow the same convention with respect to the plus / minus markings.  I think Mark said Yellow is positive and that is correct, but not all devices are marked consistently when it comes to thermocouples. Generally kiln products will be marked with one side red so simply match up all the reds. In China, red is positive and yellow is negative. Anyway, not worth getting in the marking debate and just flip them around and try it. If it’s made for K type thermocouple there is very little else that can go wrong.

K thermocouples simply act as a little battery. They produce a small voltage dependent on temp. At 77 deg f a k thermocouple will output 1 mvdc. At 78 deg f it will output 1.023 mvdc. Mvdc = millivolts dc or thousandths of a volt. Your meter is simply calibrated to display as temperature.

Thermocouples themselves are simply two different types of metal  often joined with a special clean weld at the tip. Tcouple wire is made the same way, one wire chromel and one wire alumel. in a pinch if a tcouple fails technicians will strip the leadwire back twist join the two  and use the lead wire itself  as a temporary thermocouple. Just an emergency thing though, the joint won’t last and accuracy quickly goes away.

The downside to using an old school meter is they generally have no means of being temperature compensated. For kilns, not a big issue actually because we are talking 2000 degrees. Keep the meter in a relatively cool spot.

[Mark C.]

Amazon has a bunch of cheaper ones under $75 -all from china

They cost less than a quaility analog guage

The thing is digital tells you the smaller rises in temperature where the analog is really a crude guide in temp. rise

 

https://smile.amazon.com/Pyrometer-Annealing-Thermometer-Thermocouple-Fahrenheit/dp/B01DMQOWD4/ref=sr_1_8?dchild=1&keywords=kiln+thermocouple&qid=1607879704&sr=8-8

[Msheffield]

On 12/9/2020 at 3:36 AM, Bill Kielb said:

Just change the polarity and see if the meter works. Not all tcouple markings follow the same convention with respect to the plus / minus markings.  I think Mark said Yellow is positive and that is correct, but not all devices are marked consistently when it comes to thermocouples. Generally kiln products will be marked with one side red so simply match up all the reds. In China, red is positive and yellow is negative. Anyway, not worth getting in the marking debate and just flip them around and try it. If it’s made for K type thermocouple there is very little else that can go wrong.

K thermocouples simply act as a little battery. They produce a small voltage dependent on temp. At 77 deg f a k thermocouple will output 1 mvdc. At 78 deg f it will output 1.023 mvdc. Mvdc = millivolts dc or thousandths of a volt. Your meter is simply calibrated to display as temperature.

Thermocouples themselves are simply two different types of metal  often joined with a special clean weld at the tip. Tcouple wire is made the same way, one wire chromel and one wire alumel. in a pinch if a tcouple fails technicians will strip the leadwire back twist join the two  and use the lead wire itself  as a temporary thermocouple. Just an emergency thing though, the joint won’t last and accuracy quickly goes away.

The downside to using an old school meter is they generally have no means of being temperature compensated. For kilns, not a big issue actually because we are talking 2000 degrees. Keep the meter in a relatively cool spot.

Thanks for the explanation! I tried swapping the wires around, and even mismatching them, first on the pyrometer, then on the thermocouple. Nothing worked - the needle will not budge from 0. Could my pyrometer be faulty? Maybe I'm missing something....

[Msheffield]

On 12/13/2020 at 7:19 AM, Mark C. said:

Amazon has a bunch of cheaper ones under $75 -all from china

They cost less than a quaility analog guage

The thing is digital tells you the smaller rises in temperature where the analog is really a crude guide in temp. rise

 

https://smile.amazon.com/Pyrometer-Annealing-Thermometer-Thermocouple-Fahrenheit/dp/B01DMQOWD4/ref=sr_1_8?dchild=1&keywords=kiln+thermocouple&qid=1607879704&sr=8-8

Thanks for the link!

[Bill Kielb]

4 hours ago, Msheffield said:

Could my pyrometer be faulty? Maybe I'm missing something....

Most likely the meter or it’s not built for a type K thermocouple. Odd! Anyway if you have a volt meter just test the thermocouple. It will read in millivolts (Dcv). You can confirm it rises just by warming with your hand once connected to your voltmeter or even torch the thermocouple a bit to get it to rise. You actually might try that hooked to the pyrometer meter you have,  just in case it’s not very responsive till you get up to a few hundred degrees.

It takes such a small amount of voltage to operate an analog meter like you have which means  they are usually very sensitive to vibration. The pointer generally freely travels so bumping or shaking it lightly usually results in significant needle deflection. The return spring on that meter should be super light.

The result is usually they lock the needle down for shipping so also make sure the zero adjust has not been preset to limit needle movement during shipping. Other than that, if you can do the voltmeter test it will confirm if the thermocouple is fine and the analog meter you have is stuck or bad. Generally bad thermocouples are easy to spot so hopefully the analog meter you have is locked down or is just not sensitive at low temps.

Even cheap digitals have a big advantage in accuracy and mechanical longevity. Analog meters are not common anymore.

[Msheffield]

12 hours ago, Bill Kielb said:

Most likely the meter or it’s not built for a type K thermocouple. Odd! Anyway if you have a volt meter just test the thermocouple. It will read in millivolts (Dcv). You can confirm it rises just by warming with your hand once connected to your voltmeter or even torch the thermocouple a bit to get it to rise. You actually might try that hooked to the pyrometer meter you have,  just in case it’s not very responsive till you get up to a few hundred degrees.

It takes such a small amount of voltage to operate an analog meter like you have which means  they are usually very sensitive to vibration. The pointer generally freely travels so bumping or shaking it lightly usually results in significant needle deflection. The return spring on that meter should be super light.

The result is usually they lock the needle down for shipping so also make sure the zero adjust has not been preset to limit needle movement during shipping. Other than that, if you can do the voltmeter test it will confirm if the thermocouple is fine and the analog meter you have is stuck or bad. Generally bad thermocouples are easy to spot so hopefully the analog meter you have is locked down or is just not sensitive at low temps.

Even cheap digitals have a big advantage in accuracy and mechanical longevity. Analog meters are not common anymore.

I will test the thermocouple soon when I get the chance. I have tried actually putting the thermocouple inside the kiln at a low-ish temperature, but that did nothing. How would I go about unlocking the needle or checking to see if it's locked? Yes, I am convinced to get a digital one! I just want to see if the little analog can be convinced to do something or not. It came with no instructions whatsoever, so the needle might be locked for all I know. 

[Bill Kielb]

It actually should move freely with gentle shaking, if not it might be locked. Sometimes it’s possible to turn the zero adjust screw to lock it from moving very far upscale from zero for shipping purposes.

[Mark C.]

Is that a flat slot on plastic in circle on  face if yes that is the adjustment. I doubt a small gauge like that has an adjustment..Maybe the wires are hooked up backwards if it will not climb

[Msheffield]

15 hours ago, Bill Kielb said:

It actually should move freely with gentle shaking, if not it might be locked. Sometimes it’s possible to turn the zero adjust screw to lock it from moving very far upscale from zero for shipping purposes.

It does move if I shake it a little, so not locked. Volt meter it is!

[Msheffield]

15 hours ago, Mark C. said:

Is that a flat slot on plastic in circle on  face if yes that is the adjustment. I doubt a small gauge like that has an adjustment..Maybe the wires are hooked up backwards if it will not climb

I tried turning it with a screw driver, and it does adjust it. I have tried the wiring backwards, forwards, and mixed, and still nothing!

[Bill Kielb]

Hmm, measure your tcouple with a voltmeter ought to tell the final tale.only thing left would be your tcouple connection to the holder and wire connection to the holder as well. Measuring seems to put all this to rest.