Calibration and re-ranging are both processes used to ensure the accuracy and reliability of measurement instruments, but they involve different procedures and objectives. Here's a breakdown of the differences between calibration and re-ranging:

1. Calibration:

   • Calibration is the process of comparing the measurements of an instrument to known standards to determine and adjust for any errors.
   • The primary goal of calibration is to ensure that the instrument provides accurate and reliable measurements within its specified range.
   • Calibration involves adjusting various parameters of the instrument, such as zero point, span, linearity, and sensitivity, to align its output with the expected values.
   • Calibration ensures that the instrument meets specified accuracy requirements and complies with regulatory standards or quality assurance programs.
   • Calibration may involve adjustments to correct drift, wear, or other factors affecting the instrument's performance over time.
   • Calibration typically involves traceability to national or international standards and may require certification by accredited calibration laboratories.

2. Re-ranging:

   • Re-ranging is a specific type of adjustment made to change the measurement range or scale of an instrument.
   • The primary goal of re-ranging is to modify the instrument's measurement range to accommodate different operating conditions or requirements.
   • Re-ranging does not necessarily involve comparing the instrument's measurements to external standards or adjusting for errors.
   • Re-ranging may involve adjusting the zero and span settings of the instrument to change its measurement range while maintaining its accuracy and reliability within the new range.
   • Re-ranging may be necessary when the instrument needs to measure different ranges or magnitudes of the measured variable than its original design or calibration.
   • Re-ranging may be performed as part of the initial setup of the instrument or as a maintenance procedure to adapt the instrument to changing process conditions or requirements.

In summary, calibration involves adjusting an instrument to ensure its measurements align with known standards and meet specified accuracy requirements, while re-ranging involves modifying the instrument's measurement range to accommodate different operating conditions or requirements without necessarily adjusting for errors. Both calibration and re-ranging are essential for maintaining the accuracy and reliability of measurement instruments in various applications.