What Thermocouple(s) would be best for use with a dual output pyrometer on an automotive application?

Question

I'm trying to wire up a dual display pyrometer as an exhaust gas temperature (EGT) gauge. It needs to meter 1200F (~600C) to about 2000F (~1100C) and be able to be permanently attached to the exhaust.

So what are the properties of the K- thermocouple. That was the one i was leaning toward given it's temperature range, but i don't really know anything about them.

Can it be for example screwed into an open bung in an exhaust system?

I need to determine EGT's for two separate rotor housings so that i can detect a lean condition in one or the other.

An air/fuel gauge can do this for the engine but not for individual housings.

Where would i buy a k-thermocouple?

Answer 1

Chromel-Alumel. If I remember correctly it's "Type- K" and will be linear through that temperature range (it's linear range= -190C to 1260C). Just remember that your "digital temp guage" (is not a pyrometer) must be programmed to receive the millvolt output range of the thermocouple or at least that portion of the range displayed on the temp gage (Not a Pyrometer). If the temperature gage is not programmable then you must find the thermocouple that matches the input millivolt range of the temp gage.

A "pyrometer" does not have to be wired up and does not need a thermocouple to detect heat. A pyrometer is a non-contact detector and a thermocouple needs to make contact with the heat source. They are two totally different ways of measuring heat. A pyrometer optically detects and measures radiation and converts it to a temp measurement.

A thermocouple detects and measures molecular activity and converts it to a milli-volt signal.
I hope this info helps in your endevour.

Note; A thermocouple is just two dissimular metal wires that; when, connected at one end generate a linear millivoltage when heated. You can just tack weld them to your exhaust system. Or, you could weld it to a bolt and screw it into your system (bung). You should be able to buy them at radio shack or any simular electronics shop.. some VOMs (volt ohm meters) have a place to plug (the other end of the wires) thermocouples into and read-out the temp directly. They sell those at radio shack and other electrical shops also. You can look-them-over while your there. They might even have a cheap type k digital that you can plug the wires into..If you tack weld them you must make sure that the wires are still touching each other and not just the other metal otherwise you will get an error in your reading. So twist them together real good before tacking.
Type "K" just means one wire is chrome and the other is aluminum (alloys)

Answer 2

Go on-line to the Omega corporation's web site. They know and sell everything there is to do with thermocouples. Totally everything. Good engineering tutorials to fill your knowledge gaps, good selection of probes for all sorts of applications. One-stop place.

Answer 3

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