Thermocouples are the main factors causing the measurement error

1, the influence of the insertion depth 1) Temperature measuring point of thermocouple installation location choice, the choice of the temperature measuring points is * important, temperature measuring point position, representative and typicality, 2) Insertion depth of thermocouple insertion under test sites, the heat flow along the length direction sensor, when the environment temperature low there will be heat loss, making thermocouple do not agree with the temperature of the measured object measurement error is produced. Anyhow, caused by heat conduction and error, associated with inserting depth, and insert depth related to the protection tube material. Metal protection tube because of its thermal performance is good, the insert depth should be deeper, good insulation, ceramic tube material can be inserted into the shallow some, for engineering measuring temperature, insert depth related to the measurement object is static or flowing state. 2, the influence of the contact method of temperature measurement response time is the basic principle of temperature measuring element to reach thermal equilibrium and the measured object, therefore, needs to keep a certain time when measuring temperature, to make both achieve balance, but we keep the length of time, with temperature measuring elements related to the thermal response time. Thermal response time mainly depends on the structure of sensor and measurement adjustment, the difference is larger. For temperature change a big place to be tested, especially instantaneous changes, requires the sensor response time soon, ordinary sensor not only keep up with the speed of change in the temperature of the object, also can not meet the measurement error resulting from the thermal equilibrium, * good choice fast response of the sensor. 3, the influence of thermal radiation thermocouples inserted into the furnace, the thermal radiation emitted by objects will be a very high heat, jiading in furnace gas is transparent, and thermocouple and furnace wall temperature difference, the temperature measurement error caused by energy exchange. Only to reduce the thermal error, increase the heat transfer, and as close as possible to make the furnace temperature thermocouple temperature, in addition, to avoid thermal radiation from solid when installation, make its cannot be radiation to the surface of a thermocouple, thermocouple * good with thermal radiation shielding.