The ability of an instrument to maintain certain performance over time under specified operating conditions is called stability. Instrument stability is a performance index that instrument workers in chemical enterprises are very concerned about. Due to the relatively harsh environment in which chemical enterprises use instruments, and the relatively large changes in the temperature and pressure of the measured medium, the ability of certain components of the instrument to remain unchanged over time will be reduced and the stability of the instrument will be reduced when the instrument is put into use in this environment. There is no quantitative value for instrument stability, and chemical enterprises usually use instrument zero drift to measure instrument stability.

Instrument accuracy is called precision, also known as accuracy. Accuracy and error can be said to be twin brothers, because there is error, there is the concept of accuracy. In short, the accuracy of an instrument is the degree to which the measured value of the instrument approaches the true value, usually expressed as a relative percentage error (also known as a relative reduced error).