thermocouple or thermal resistance of selection

When we measure temperature, we often face the choice of thermocouple or thermal resistance, which are two kinds of sensors commonly used in the field of industrial automation. When using, we choose according to the following product characteristics:

1、 Choose the right product according to your long-term use temperature range:

1. Copper thermistor graduation number cu50 range - 50 -- 100 degrees [150]

2. Platinum thermistor graduation number PT100, range - 200 -- 420 degrees [650]

3. Platinum thermistor graduation number pt10, range 0-650 degrees [850] [non standard product, customized]

4. Nickel chromium copper nickel thermocouple graduation number e, range 0-800 degrees [1000]

5. Nickel chromium nickel silicon thermocouple graduation K, range 0-1000 degrees [1300]

6. Ni Cr Ni Si thermocouple graduation n, range 0-1000 degrees [1300]

7. Pt Rh 10 Pt thermocouple scale s, range 0-1400 degrees [1600]

8, Pt Rh 30 Pt Rh 6 thermocouple graduation B range 0-1600 degrees [1800]

9, Pt Rh 13 Pt thermocouple graduation R range 0-1400 degrees [1650]

10, Fe constantan thermocouple graduation J range 0-500 [800]

11, copper constantan thermocouple graduation number T range - 200-300 degrees [350]

12, tungsten rhenium 3-tungsten rhenium 25 degree C range 0-2300 degrees [vacuum, inert gas environment use]

Note: 1. The number in brackets is the theoretical * high value, which should not be used as long-term data. Generally speaking, thermal resistance has better accuracy advantages than thermocouple, but its short life, insufficient stability, slow response speed and insufficient wide temperature range are also the short boards restricting its further development.

2、 Select the material of the protective tube according to the use environment:

1. Quartz glass is resistant to acid and alkali corrosion, heat shock and fragile at 0-1200 ℃. It can be used to measure temperature of molten copper, aluminum, lead and zinc

2. 321 stainless steel 0-1000 degrees, high temperature oxidation resistance. It is widely used in the field of thermal processing and processing to measure the temperature of fluid and gas

3. 316 stainless steel 0-1000 degrees, high temperature oxidation resistance, acid and alkali corrosion resistance. It is widely used in the field of thermal processing and processing to measure the temperature of fluid and gas

4. 310S stainless steel 0-1150 degree, high temperature oxidation resistance. It is widely used in the field of thermal processing and processing to measure the temperature of fluid, gas and flame

5. GH3030 stainless steel, 0-1200 degrees, high temperature oxidation resistance. It is widely used in the field of thermal processing and processing to measure the temperature of fluid, gas and flame

6. Gh3039 stainless steel, 0-1250 degree, high temperature oxidation resistance. It is widely used in the field of thermal processing and processing to measure the temperature of fluid, gas and flame

7. High alumina ceramics 0-1400 degrees, high temperature resistance, oxidation resistance, fragile. It is widely used in the field of thermal processing and processing to measure the temperature of gas and flame

8. Corundum 0-1650 degree, high temperature resistance and oxidation resistance. Fragile. It is widely used in the field of thermal processing and processing to measure the temperature of gas and flame

9. Silicon carbide 0-1650 degree, high temperature resistance, oxidation resistance, erosion resistance, corrosion resistance, fragile. It is widely used in the field of thermal processing and processing to measure the temperature of gas and flame

10. Polytetrafluoroethylene is 0-200 degree resistant to all acid and alkali corrosion.

11. High temperature wear-resistant alloy is 0-1250 degree resistant to wear of measured medium, which is widely used in power plants and cement plants,

12. Hastelloy 0-1250 degree, high temperature resistance, oxidation resistance, corrosion resistance.

13. High chromium cast iron 0-1100 degree, high temperature resistance, erosion resistance, especially sulfuric acid corrosion resistance.

3、 Correct selection of protection tube diameter to ensure measurement and control

The selection of protection tube is very important. In theory, the smaller the diameter and the thinner the wall thickness of the protective tube, the faster the temperature response, the thicker the diameter, the greater the inertia, the slower the reaction and the worse the temperature control accuracy. Of course, it is necessary to consider the corrosion, oxidation, pressure, friction, impact and other factors of the measured material on the protection tube.