Instrument reliability is another important performance index pursued by instrument workers of chemical industry group. Reliability and instrument maintenance are opposite to each other. Instrument reliability is high, instrument maintenance is small, otherwise instrument reliability is poor, instrument maintenance is large. For the inspection and process limiting instruments of chemical industry group, most of them are installed on the process pipelines, various towers, kettles, tanks and reactors. Moreover, the continuity of chemical production and most toxic, flammable and explosive environments add many difficulties to the instrument maintenance. One is to consider the safety of chemical production, the other is related to the personal safety of instrument maintenance personnel, Therefore, the less maintenance is required for consumption inspection and process limiting instruments in chemical industry group, the better, that is, the instrument reliability is required to be as high as possible.
With the upgrading of instruments, especially the introduction of microelectronics technology into the instrument manufacturing industry, the predictability of instruments is greatly improved. Instrument manufacturers pay more and more attention to this performance index, and usually use MTBF to describe the reliability of instrument. The MTBF of a fully intelligent transmitter is about 10 times higher than that of ordinary non intelligent instruments such as electric III transmitter, which can be as high as 100 ~ 390 years.
