Armoured thermocouple fault causes and solutions

Armoured thermocouple I think we must is a familiar one of the commonly used temperature measuring device. When armoured thermocouple temperature measurement choose the location of the temperature measuring point * important, armoured thermocouple insertion under test site, along the length direction of the sensor will produce heat. When the environment temperature low heat loss. The thermocouple temperature sensor do not agree with the temperature of the measured object and produce temperature measurement error.

all in all, the error induced by heat conduction, related to the insertion 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 a little bit deep, ceramic material thermal insulation performance is good, can be inserted into the lighter. For engineering measurement, the insert depth is also related to such as the measured object is static or flowing, such as the flow of liquid or high-speed airflow temperature measurement, will not be restricted by the above, the insert depth can be lighter, concrete numerical value should be determined by experiment. When measuring temperature, therefore, need to keep a certain time and to make both reach thermal equilibrium. While keeping the length of time, with temperature measuring elements related to the thermal response time. And thermal response time depends on the structure of the sensor and measurement conditions, the difference is great. For the gas medium, especially the static gas, at least should be a balance of more than 30 seconds to reach; For liquid, * over 5 seconds faster.

the temperature measured, the changing instantly change process, in particular, the whole process of only 1 second, insist on the sensor response time in milliseconds. Ordinary temperature sensor, therefore, not only to keep pace with the speed of change in the temperature of the object appear lags behind, and the measurement error due to reach thermal equilibrium. * good choose fast response of the sensor: except for thermocouple protection tube, diameter of the measuring junction of the thermocouple, and the main factors that accidentally silk the thinner, measuring the diameter of the smaller, shorter its thermal response time.

armoured thermocouple faults and solve measures:

armoured thermocouple ceramic pores blocked components will be failure, often adopts the electric dust removal method to deal with, but the effect is not ideal, and cannot be used in inflammable and explosive environment, can more accurately and quickly to reflect the actual temperature of end face, is suitable for measuring temperature bearing and other parts of the face. It is not only widely used in industrial temperature measurement, and is made into standard benchmark instrument. It has matched display instrument to choose from.

not standardized thermocouple or on the order of magnitude less than the range using standardized thermocouple, generally there is no unified indexing table, mainly used for the measurement of some special occasions. Thermoelectric emfs end temperature into a single value function relation with work. All kinds of thermocouple relationship between temperature and thermoelectric emfs indexing table are made at the cold end temperature is zero, so the use of special compensation conductor should be extended to the cold end.

main failure forms, one is caused by the vibrating wire fracture, fracture and thermocouple is caused by the bending thermocouple short circuit or a breakout.

armoured thermocouple and display instrument, usually record instrument, electronic computer and other systems. Direct measurement of the 0 - in the process of production 1300 degrees within the scope of liquid, steam and gas medium and solid surface temperature.

installation note

1, briquetting installation height must agree, usually above the level of 150 ~ 200 mm;

2, press block with three spot welding welding requirements, thermocouples inserted into the mouth not to spot welding, the side should pay attention to don't stop screws to resistance spot welding is dead;

3, pipe wall temperature should be symmetrical installation;

4, armoured thermocouple must be inserted in place, locking screw tightly in place;

5, armoured thermocouple leads to recommend the use of small tray;

6, the substitution of constant must use the stainless steel wire armoured thermocouple;

7, armoured thermocouple and the wall outlet must dress, and then through the self-made protection tube raises;

8, in order to prevent the settlement of the boiler, it is recommended to use transition junction box, and then use compensation conductor should be connected to the front;

9, furnace wall and front of the bridge or protecting tube should not be enclosed, to prevent the high heat flow directly into the front-end and the inside of the damaged components ( Tianjin turbine because didn't pay attention, causes the damage of the front-end) ;

10, front-end installation location not too far, otherwise the thermocouple length is not enough;

11, connection should be correct and reliable.