The change of the face value of the thermocouple _ instrument

Thermocouple is a kind of common measuring instruments, in many areas of a certain application. End of thermocouple resistance can be change, so a lot of people are relying on this point to the line of industrial measurement. End thermocouple is the use of its resistance varies with temperature change made of the principle of converting temperature measured the amount of resistance temperature sensor. Temperature transmitter, temperature controller, PLC temperature measuring equipment such as a template by applying a known to end thermocouple exciting current measuring method of both ends of the voltage resistance, converted to temperature, the resistance value so as to realize temperature measurement. Temperature measuring device generally has four input terminals. Among them the I +, I - Provide constant current to end thermocouple, v + and v - Used to detect the end of the thermocouple voltage variation, and testing according to the temperature change. End surface thermocouple used in industrial water, water, sewage with weak corrosive medium, such as applicable to petroleum, chemical industry, iron and steel industries and municipal, environmental protection and other fields. Alloy b protection tube, below the boiling point for all the concentration of hydrochloric acid have good corrosion resistance, resistant to sulfuric acid, phosphoric acid, hydrofluoric acid, organic acids and other non chloride acid, alkali, corrosion of non oxidizing salt solution. Alloy c protection tube: non oxidizing acid, such as nitric acid, mixed acid, or a combination of chromic acid and sulfuric acid medium corrosion, oxidation resistance and salt fe++ +, cu++ or contain other antioxidant corrosion, such as higher than normal temperature hypochlorite solution, the corrosion of the water. Titanium protection tube: water, all kinds of chloride and hypochlorite, oxidizing acid, organic acid, alkali corrosion. Not a pure reducing acid corrosion resistance, but contains antioxidants, such as acid corrosion is greatly reduced. Ptfe protection tube, is a kind of plastic chemical performance is stable, capable of boiling water and hydrochloric acid, sulfuric acid, nitric acid, strong alkali and a variety of organic solvents. Don't three chlorine fluoride, high temperature resistant chlorine, high-speed liquid fluoride, fluoride liquid oxygen, ozone corrosion.