5.2 Contact sensors
For thermal sensors that are allowed to make contact with the subject or medium to be measured there exist a number of possible sensors
They are subdivided in several types:
- RTD's (thermistors, PT100's, diodes, Semiconductor Temperature Sensors)
- Other types (expansion, bimetallic, optic, etc.)
For the first 3 types the most striking (dis)advantages are summarised in the table below.
|Operating Range||-200 °C to 2000 °C||-250 °C to 850 °C||-100 °C to 300 °C|
1 °C common
0.03 °C common
0.1 °C common
|Cost||Low||High||Low to moderate|
|Long term stability||Low||High||Medium|
|Cost of measuring instrument||Medium||High||Low|
|* Linearity is not an issue if using modern digital measuring instruments, as look-up tables stored in memory provide compensation.
** Thermal response is considered for the measuring element only, not its enclosure.