The difference between zero elevation and zero suppression in the transmitters
One of the most common misconceptions when dealing with transmitters is zero height and suppression. Height adjustment and suppression are often necessary in measuring the liquid level when the transmitter cannot be installed on a level zero surface of the tank. The definition is as follows, but to understand altitude and repression is the simplest if you look at it from a mathematical point of view, which is explained in the second part of this paragraph
For an increased zero range, the value of the zero measurement variable is higher than the lower range value. This may be expressed either in units of variability or in percentages.
For a suppressed zero range, the value of the measured zero variable is lower than the amplitude value. It may be expressed in variable units or expressed as a percentage of aperture.
You can mathematically create equations that allow you to calibrate the transmitter for any application that requires zero height or suppression. It is important to understand some basic facts about differential pressure transmitters. First, to obtain an increasing output, the upper side of the transmitter must always be increasing in pressure relative to the lower side. Therefore, to achieve a 20 mA output, the net result of all forces on both the top and bottom sides of the transmitter must be such that the top side is larger than the bottom side with a value equal to the calibrated aperture of the transmitter. Second, the purpose of calibration biases (altitude and suppression) is to apply differential pressure in cases where the output is 4 mA in some places other than the desired differential pressure.