The fundamental problem with surface temperature measurement is that it is subject to large stem conduction errors, also because heat conducted from the surface of the hot plate causes a localized cold spot to be created. It means that the temperature indicated by the hot plate is not necessarily the temperature at the point of measurement.
An ideal system would not disturb the heat flux from the hot plate, which is exactly what 944 system does.
Principle of operation
A fine wire type N thermocouple is used as the surface temperature sensor. A second junction of 2 to 3 mm along the thermocouple senses the temperature difference due to heat flux along the sensor.
A heater heats the thermocouple stem until the temperature gradient is zero, thus creating a measurement without stem conduction, or disturbance of the hot plate’s surface.
944 system can be used with the surface sensor calibrator 983.
|Temperature range||30°C to +350°C|
|Accuracy||±2°C with traceable certification
±5°C without certification
|Probe assembly||Diameter: 7.5 mm
Length: 150 mm
Lead length: 850 mm
|Size||90 x 153 x 265 mm|
|Display||Resolution: 0.1°C or 0.1°F|
|Power supply||100 / 120 V (50/60 Hz) or 200 / 240 V (50/60 Hz)|