K type thermocouple of the main causes of the leakage and prevent method

K type thermocouple is becoming more and more widely in use in production, the thermocouple has become the industry one of the most commonly used temperature detecting element, it has high measurement precision, wide measuring range, simple structure, convenient use, etc. We know through various channels and analysis products, for the majority of netizens to present various industry knowledge.

K type thermocouple leakage reason

( 1) On the furnace refractory at high temperature insulation fault, equipped with wire furnace furnace wall inserted with metal wire contact with thermocouple, thermocouple is easy to make furnace refractory brick is a good insulating material, at room temperature but as temperatures rise, insulation performance will drop significantly, table 1 lists the three different firebrick resistivity at different temperatures. Resistance furnace lining with alumina refractory brick for the most part, with the temperature rise can be seen from the table 1 its resistance value is significantly reduced.

( 2) Furnace wire contact with thermocouple, platinum, rhodium thermocouple protection tube is alumina ceramic tube, accidentally silk made separation insulation porcelain tube wear, under the high temperature insulation performance will reduce. Table 2 lists AL203 resistivity at different temperatures. By it can be seen in table 2, under the high temperature refractory insulation performance, caused the leakage, the leak to the thermocouple, so there is ac leakage on the thermocouple signals.

K type thermocouple leakage prevention method 1, keep the thermocouple is not in contact with the refractory brick.

2, negative ground thermocouple, eliminate the leakage on the thermocouple signal.

3, installation of filter device in the thermocouple output.

4, from the hot junction thermocouple leads to earth ground.

5, on the thermocouple tube and jacket heat-resistant steel pipe or carborundum tube, and make it grounded.