I'm a computer tech and a motorcycle mechanic. I'm into tuning vintage Vespa 2 stroke scooters. I want to create my own digital display to help with tuning and am looking to use a K type Thermocouple to record my exhaust gas temperature. Starting with a simple search on eBay I've found a large variety of K thermocouple at different prices. Most of the ones associated with automotive aspects are really expensive while more generic ones have a more reasonable price. Should I be cautious of cheap sensors from China? From what I've read my average temp reading should be between 600-700C. Should I select a sensor that this reading will fall in the middle of or at the higher end of the spectrum? Just wanted to get some opinions and maybe some sources for good reasonably priced sensors.
A K-type thermocouple junction is capable of a large temperature range; the problem lies in how it's made. For example, if the manufacturer uses PVC for the insulation it may not even be good for boiling water (insulation will soften/melt and allow wires to short). If you plan to submerse it in liquid, it must be in an insulated probe. There are lots of probes because there are lots of applications.
A cheap one designed for an HVAC tech to test air temperatures on your heater/air conditioner wouldn't work at all for me to measure the temperature of my soldering iron tip.
Get one that's rated a comfortable margin above the temperature where you expect to operate.
-j
Check appliance shops, you might be able to find one intended as a replacement for a digitally-controlled kitchen range oven, that should have a range a lot wider than the Vespa should need. In a situation like this, overkill = durability.
I worked with TC sensors for decades in a oil refinery. I would strongly recommend getting a FREE temperature measurement manual from Omega Engineering. It has a lot of general theory and information about all kinds of temp sensors, not just about products they sell. It is a great reference manual to have.
http://www.omega.com/literature/6thedition/
Lefty
Omega carries stainless steel sheathed type K probes with high temperature miniature connectors for $30. See:
Thanks for the Omega link, that is kind of what I'm looking for. I'm probably going to use the 1/4 or 1/8 NPT fitting type or a 2 to 3 inch probe type with a clamp.
