Zero suppression and zero elevation are terms commonly used in instrumentation, particularly in pressure measurement, to adjust the zero point or baseline of a measurement instrument relative to a reference point. Here's an explanation of each:

1. Zero Suppression:

   • Zero suppression refers to the adjustment of the instrument's output signal or display so that the zero point of the measurement scale is shifted away from its actual zero value.
   • In other words, zero suppression shifts the entire measurement scale upwards or downwards while maintaining the same measurement range.
   • Zero suppression is typically used to compensate for a baseline pressure or signal that is consistently higher or lower than zero, such as atmospheric pressure or a pre-existing pressure in a system.
   • For example, if a pressure transmitter measures a baseline pressure of 5 psi when there is no pressure applied, zero suppression may be used to adjust the transmitter's output signal so that it reads zero at 5 psi instead of the true zero pressure.

2. Zero Elevation:

   • Zero elevation, on the other hand, refers to the adjustment of the instrument's output signal or display so that the zero point of the measurement scale is shifted towards its actual zero value.
   • In contrast to zero suppression, zero elevation moves the entire measurement scale upwards or downwards while maintaining the same measurement range.
   • Zero elevation is typically used to compensate for a baseline pressure or signal that is consistently higher or lower than the desired zero reference point.
   • For example, if a pressure transmitter measures a baseline pressure of -2 psi when there is no pressure applied, zero elevation may be used to adjust the transmitter's output signal so that it reads zero at -2 psi instead of the true zero pressure.

In summary, zero suppression and zero elevation are methods used to adjust the zero point or baseline of a measurement instrument relative to a reference point, either by shifting the entire measurement scale upwards or downwards. These adjustments help ensure accurate and reliable measurement readings by compensating for baseline pressures or signals present in the system.