Pyrometer Tech

biggy238

biggy238

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I'm not sure that I've ever seen a thread dedicated strictly to this, and I'm hoping maybe we can get some probes sourced that have a faster response time.
I will pick at the thread as I get time. I know I've read quite a bit on the Omega probes, but it's been a while.
Feel free to contribute. I would like to start with basic knowledge of the K type that almost all of us use, and look at some of the others available from other tech fields.
Kyle

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Thermocouples depend on metals experiencing temperature changes to produce a magnetic field. There are types other than the K that can respond quicker but they are generally for lower temperature uses. For good reason as the metals that are more conductive generally do not survive well at high temperatures. This may be a horrible example but think of aluminum vs steel. Take a torch and you can get aluminum hot in a hurry and it cools in a hurry. Steel does neither in a hurry but it obviously survives the torch blowing on it much longer. You are depending on a metal experiencing changes around it so it generally takes some time for it to stabilize and produce an accurate reading.

Now if you could somehow get an infrared sensor to survive in an automotive setting then you could have something fairly quick and accurate.


That is about the extent of my pyro knowledge. In for the reading LOL
 
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I would like to know who manufactures Cat's 5V ready sensors.

What is a realistic goal for response time VS what is being seen now. The probes I work with take between 1-3 seconds to report a significant swing in temperature.

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As far as I know, within the "K" classification, the diameter of the TC is what effects response time as much as anything. Going with a 1/16" probe or smaller will help alot. But if you're running it pre-turbo, there's greater risk of a smaller probe failing and going through the turbo. Granted, that's happened to us before with no apparent damage...but I'm not sure that's a good thing to do in general.

http://www.omega.com/techref/ThermocoupleResponseTime.html

What are you using to read the TC? If you're not using a digital display with high sampling rate, the stepper motor in the analog gauge may be the biggest limiter...
 
When I get done, mine will be run through a 5V amp and then to an AVR running at 16mhz to run a 16X2 LCD display.
If I get fancy it will go to a TFT screen, but that's down the road

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Thermocouples do not work by magnetic field. They generate a tiny (millivolt) electrical signal that changes as the junction between the 2 different metals is heated.

The fastest responding TCs are fine bare wires (called exposed junction). However most guys will end up using sheathed TCs because they can be sealed most easily. Get the ones with inconel sheaths. Used ungrounded junctions when possible to prevent any stray signals from entering the circuit. I have used 1/16" inconel K-types with zero issues and zero melting. The further you stick the TC out into the mainstream of gas flow, the faster it will react but the hotter it will get because obviously the only thing cooling it (at WOT) is the sheath (heat does travel down it to whatever fitting you're using). Of course when you snap out of the throttle the exhaust gas will cool it quickly. If you peel the sheaths open you will find the 2 wires suspended in a ceramic powder that insulates them electrically from each other and the sheath in an ungrounded junction TC. This is one reason that response can be slow, especially as the diameter goes up.

TC connectors MUST be made for the type of wire being used. K-Type use Chromel and Alumel wires and the connectors and wire all the way to the amplifier/module must be the same stuff and wired correctly. K-type wire is almost always red and yellow leads. Make sure you have them hooked up right.

If you want to really drive yourself crazy, use some extension wire that's either improper polarity, or use copper. The extra junctions created can give you numbers all over the place.
 
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I use probes from The Sensor Connection, if you want quick probe buy thinner and /or open type but the limiting factor will most propably be the gauge. The quickest I've had was VEMS probe and their combined EGT/AFR gauge even if it was turbo approved closed type probe.
 
So ultimately nothing can be done at the TC end, only the sampling end.

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biggy238 said:
So ultimately nothing can be done at the TC end, only the sampling end.

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Click to expand...

Can you not read?

If you want to spend the time to implement exposed junction fine wire TCs, you can have nearly instant response.
 
nwpadmax said:
Can you not read?

If you want to spend the time to implement exposed junction fine wire TCs, you can have nearly instant response.
Click to expand...
Why be indignant? Yes, I can read. I misspoke.

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Well, youz was questin for gnawlidge, and I spells it out to yas, and you turns it around and sez like mang I caint do shizzle, right?, and I be like, WTF mang, yes you cain.
 
nwpadmax said:
Well, youz was questin for gnawlidge, and I spells it out to yas, and you turns it around and sez like mang I caint do shizzle, right?, and I be like, WTF mang, yes you cain.
Click to expand...

This made me cringe.....big tyme
 
kleann said:
This made me cringe.....big tyme
Click to expand...
I didn't know how to respond when I read it earlier.


I'm going to try and find out more about the Bosch branded pyrometer modules. Some of theirs are even J1939 modules, but they all have small diameter shields.

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kleann said:
This made me cringe.....big tyme
Click to expand...

Why be indignant? :D

Why not just keep it all analog and be done with it? There's nothing faster if that's what you're looking for. You haven't really stated what exactly it is that you're trying to figure out.
 
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nwpadmax said:
Why be indignant? :D

Why not just keep it all analog and be done with it? There's nothing faster if that's what you're looking for. You haven't really stated what exactly it is that you're trying to figure out.
Click to expand...
Nice....

The thread isn't so much for me. Just a general tech thread.

Having a PID broadcast could be useful. I'm indifferent as to whether it's analog or digital, I can see the merit to both.

We've all seen the point where cognition is a limiting factor, and having a datalog is the only way to make use of the information.

I do intend to do port monitoring on the engine I'm building, along with monitoring the charge air in several places.



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nwpadmax said:
Thermocouples do not work by magnetic field. They generate a tiny (millivolt) electrical signal that changes as the junction between the 2 different metals is heated.

The fastest responding TCs are fine bare wires (called exposed junction). However most guys will end up using sheathed TCs because they can be sealed most easily. Get the ones with inconel sheaths. Used ungrounded junctions when possible to prevent any stray signals from entering the circuit. I have used 1/16" inconel K-types with zero issues and zero melting. The further you stick the TC out into the mainstream of gas flow, the faster it will react but the hotter it will get because obviously the only thing cooling it (at WOT) is the sheath (heat does travel down it to whatever fitting you're using). Of course when you snap out of the throttle the exhaust gas will cool it quickly. If you peel the sheaths open you will find the 2 wires suspended in a ceramic powder that insulates them electrically from each other and the sheath in an ungrounded junction TC. This is one reason that response can be slow, especially as the diameter goes up.

TC connectors MUST be made for the type of wire being used. K-Type use Chromel and Alumel wires and the connectors and wire all the way to the amplifier/module must be the same stuff and wired correctly. K-type wire is almost always red and yellow leads. Make sure you have them hooked up right.

If you want to really drive yourself crazy, use some extension wire that's either improper polarity, or use copper. The extra junctions created can give you numbers all over the place.
Click to expand...
Sounds like you know your stuff,we use tons of k type thermocouples and some j type at work and we make them all. also,red is negative while yellow is postive. Opposite of what most would think.

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At what point do you need a signal conditioner? This would be using a analog or digital gauge. I want to put a new probe on my truck using my Edge EAS system, but I don't want to use Edges Probe due to the lifespan of them.
 
Know what format the input to the edge is? I built a simple 5V amp for my diablosport several years ago

Alpha Beta Test Monkey
Guang-Zoo Turbo Systems
 
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