Long Term Stability

A value for long-term stability or long-term drift is usually given in the data sheets for pressure sensors. However, very few users are familiar with the exact meaning and, above all, the distinction between the two terms.

The long-term stability is specified in the DIN 16086 standard as the maximum change in the zero signal and output span signal of a pressure measuring instrument under reference conditions within one year. Theoretically, a sensor must therefore be stored for one year at reference conditions in order to obtain a value for long-term stability.

The long-term drift is determined under applied pressure, the long-term stability is determined without any applied pressure, but purely through the ageing of the pressure transmitter’s components. The error does not develop in a linear way over the years, but saturates after a certain time (exponential progression). A specification of the time until when this saturation state is reached is dependent on the respective application and cannot be generally defined. An individual and very costly validation corresponding to the application would be necessary to determine the signal change.