Precautions for using platinum rhodium thermocouples?

Platinum rhodium thermocouple is a commonly used type in thermocouple sensors. Platinum rhodium thermocouple has a wide range of applications and irreplaceable advantages. Below, we will introduce the precautions for using platinum rhodium thermocouple.

Platinum rhodium thermocouples can directly measure temperature and convert temperature signals into thermoelectric potential signals, which are then converted into the temperature of the measured medium through electrical instruments (secondary instruments).

The installation methods of platinum rhodium thermocouples include threaded connection, flange connection, and welding, which are suitable for different occasions and requirements, mainly determined by parameters such as pressure and temperature.

(1) When using thermocouple compensation wires, attention must be paid to model matching, polarity cannot be connected incorrectly, and the temperature at the connection end between the compensation wire and the thermocouple cannot exceed 100 ℃.

(2) When using a thermocouple with a large time constant for temperature measurement or control, although the temperature displayed on the instrument fluctuates very little, the actual furnace temperature may fluctuate greatly. In order to accurately measure temperature, a thermocouple with a small time constant should be selected.

(3) After correctly wiring and powering on according to the instrument wiring diagram, the instrument first displays the thermocouple index number of the instrument, then displays the instrument range, and then the digital tube in the lower row of the instrument displays the set temperature, and the digital tube in the upper row of the instrument displays the measured temperature.

(4) Platinum rhodium thermocouples cannot be installed in areas where the measured medium rarely flows. When using thermocouples to measure gas temperature inside a tube, the thermocouples must be installed against the flow velocity direction and fully in contact with the gas.

(5) In order to ensure sufficient heat exchange between the measuring ends of thermocouples and thermal resistors and the measured medium, the location of the measuring point should be selected reasonably and avoided near the valve as much as possible.

(6) According to the law of intermediate conductor, in practical temperature measurement applications of thermocouples, the hot end is often welded and the cold end is open circuited. The cold end is connected to the display instrument through a connecting wire to form a temperature measurement system.