The difference between industrial grade one and standard grade one of thermocouple E type

Industrial grade ones are used to measure temperature parameters in the production process, and standard grade ones are used to transfer temperature scales and calibrate industrial grade thermocouples. The price of a standard thermocouple is more than 50 times that of an industrial grade thermocouple!
Appendix A Additional type test (supplement)
A.1 Technical requirements
A.1.1 Insulation resistance under damp and hot conditions The insulation resistance value of the thermocouple should be no less than 10MΩ at the end of the constant damp and hot conditions test.
A.1.2 Unpackaged free fall At the end of the unpackaged free fall test, the thermocouple should have no mechanical damage, no open circuit or short circuit, and the insulation resistance at room temperature should comply with the provisions of Section 2.3.1.
A.1.3 Vibration At the end of the vibration test, the thermocouple should have no mechanical damage, no open circuit or short circuit, and the insulation resistance at room temperature should comply with the provisions of Section 2.3.1.
A.1.4 Pressure Thermocouples should have no leakage, no mechanical damage, no open circuit or short circuit during the test pressure, and the insulation resistance at room temperature should comply with the provisions of 2.3.1.
A.1.5 Protection against liquid intrusion At the end of the protection test against liquid intrusion, the thermocouples should have no mechanical damage, no open circuit or short circuit, no visible water marks in the junction box, and the insulation resistance at room temperature should comply with the provisions of 2.3.1.
A.1.6 Flameproof Thermocouples should be subjected to flameproof tests by a national designated agency, and the agency should issue a certificate in accordance with national regulations.
A.2 Test method
A.2.1 Insulation resistance under damp and hot conditions The test should be conducted in accordance with GB2423.3-81 "Basic Environmental Test Procedures for Electrical and Electronic Products Test Ca: Steady Damp and Heat Test Method". The test duration is 2 days. After the test, immediately measure the insulation resistance value of the tested thermocouple at room temperature in accordance with Article 3.3.
A.2.2 Free fall without packaging Before the free fall test, the tested thermocouple should be structurally intact. The test device is a 6mm thick steel plate laid on a rigid ground. During the test, the longitudinal axis of the tested thermocouple is basically parallel to the surface of the steel plate, and the distance between the two is about 250mm. Then let the tested thermocouple fall freely from this height onto the steel plate. This process should be repeated ten times. After the test, immediately check whether the tested thermocouple has mechanical damage, open circuit or short circuit, and measure the insulation resistance value at room temperature according to Article 3.3.
A.2.3 Vibration Test according to GB4451-84 "Vibration (Sinusoidal) Test Method for Industrial Automation Instruments". The vibration level can be selected as 2B or 2C according to actual conditions. After the test, immediately check whether the tested thermocouple has mechanical damage. Whether there is open circuit or short circuit, and measure the insulation resistance value at room temperature according to Article 3.3.
A.2.4 Pressure The thermocouple to be tested is placed in a pressure test tube filled with liquid, and the pressure is gradually increased to 1.5 times the maximum operating pressure and maintained for 60 seconds. At the end of the test, immediately check whether the thermocouple to be tested has leakage, mechanical damage, open circuit or short circuit, and measure the insulation resistance value at room temperature according to Article 3.3.
A.2.5 Protection against liquid intrusion According to actual conditions, one of the three levels (the severity of which is increasing) described in Articles A.2.5.1, A.2.5.2, and A.2.5.3 can be selected for testing. At the end of the test, immediately check whether the thermocouple to be tested has mechanical damage, open circuit or short circuit, and whether there are visible water marks in the junction box, and measure the insulation resistance value at room temperature according to Article 3.3. A.2.5.1 The principle of the test device is shown in Figure A. This device should have a semicircular water spray pipe that can swing back and forth, and the radius of the semicircle should be as small as possible and meet actual needs. The swing angle α of the water spray pipe relative to the vertical direction is ±60°, the half angle β of the fan-shaped water spray surface is ±60°, the time required to sweep the angle α is about 1 second, the test pressure is 0.1MPa, the longitudinal axis of the tested thermocouple is basically perpendicular to the ground, and its junction box is roughly at the center of the semicircular water spray pipe. During the water spray test, the tested thermocouple rotates 180° around its axis every 300 seconds, and the water spray test time is at least 10 minutes. This figure is an "inverted figure"
A.2.5.2 The principle and test method of the test device are the same as those of A.2.5.1. However, α is about ±180°, β is about ±90°, and the time required to sweep the angle α is about 0.5 seconds.
A.2.5.3 The test device is a water spray nozzle with an inner diameter of 12.5mm, the test pressure is 0.1MPa, and the distance from the water spray nozzle to the junction box of the tested thermocouple is 3m. During the test, the water spray nozzle should spray water to the tested thermocouple from all directions. The water spray test time is at least 15 minutes.
A.2.6 Flameproof test The test is carried out in accordance with the relevant provisions of GB3836-83 "Flameproof electrical equipment "d"".
Industrial thermocouples are composed of a pair or more pairs of hot electrodes and insulators, parts or materials used to prevent short circuits between hot electrodes and (or) between hot electrodes and protective tubes, and tubular objects that protect hot electrode assemblies from harmful environmental effects. If they are correctly connected to the thermocouple used, the reference end of the thermocouple is moved to the output end of the pair of wires. When a step change in temperature occurs, the time required for the output of the thermocouple to change to a specified percentage equivalent to the step change is usually expressed as τ.