General Questions
This is a feature of most measuring instruments which allows for the fact that the thermocouple input termination is at varying temperature other than stable at 0°C.
To eliminate the possibility of earth loops resulting in measurement errors and to reduce the danger of voltage pickup from electrical heaters.
Film uses platinum deposition on a substrate; wire wound uses a helically wound platinum wire in ceramic. Wire-wound provides greater accuracy and stability but is vulnerable to shock, whereas film type is shock resistant with quicker response.
A fabricated thermopocket uses welded construction to allow long immersion lengths, whereas a thermowell is machined from solid material.
To protect the sensor from the process medium and to facilitate replacement if required.
A sensor with two separate sensing elements in a single housing.
They have been developed over many years to suit different applications worldwide.
Type N is generally more stable and lasts longer than Type K, making it better suited for high-temperature applications.
An industry-standard platinum RTD with resistance of 100 ohms at 0°C, widely used in RTD assemblies.
Typically ±2.5°C for thermocouples and ±0.5°C for RTDs. Higher accuracy sensors are available, and 4-wire RTDs provide best stability.
Mineral insulated sheaths are flexible, while fabricated sheaths are rigid.
Two-wire should be avoided, three-wire is common, and four-wire gives optimum accuracy depending on instrument configuration.
