TIDBITS ABOUT THERMOCOUPLES
- According to ASTM color code guidelines, which apply to most North American sensor manufacturers, the Red leg is always negative.
- 2 types of thermocouples (types J and K) have one leg, which is magnetic. With these 2 types, you can use a magnet to determine polarity.
- The hot junction of a thermocouple can be made by any means possible as long as there is good, constant contact between the two wires.
- Special limits of error thermocouple sensors do not have to have special limits of error extension wire.
- Non-thermocouple materials can be used in thermocouple circuits under the right conditions. Non-thermocouple connectors, terminals and slices can be used as long as there is no temperature gradient present at the areas where these items are used.
- Extension wire does not have to be a large gauge to work in an application where the sensor is placed a long way from the measuring instrument. Most modern temperature monitoring instruments are current based so lead wire resistance is not critical.
- It is possible to get an average temperature reading using multiple thermocouples as long as the sensors are wired in parallel and the resistance of these different sensors is the same.