Basic Terms related to Calibration
An electronic pressure transmitter may have a nameplate instrument range of 0-750 pounds per square inch, gauge (psig) and output of 4-to-20 milliamps (mA). However, the engineer has determined he should calibrate the instrument for 0-to-300 psig = 4-to-20 mA. In this example, the zero input value is 0 psig, and zero output value is 4 mA. The input span is 300 psig, and the output span is 16 mA.
Note: To understand the difference between calibration and instrument range, let's consider an example. A Calibration Technician receive pressure gauge of 300 psi and instructed to calibrate that gauge from 0 to 100 psi according to process requirement. Technician will calibrate the pressure gauge within it’s decided calibration range (0~100psi) and not according to its instrument range (0~300psi). Calibration can be performed on 0, 25, 50, 75 and 100% of its calibration range.
Zero Input Value: 0 psi
Input span: 100 psi