This article discusses some critical items to address for a calibration program based on sound metrology fundamentals without a complete overhaul of the calibration program. Having properly calibrated process control instrumentation provides a high quality of process control, a process that will operate to design specifications, and prevents the process from being stressed as it compensates for inaccurate measurement data feeding the DCS. Realization of these benefits may be challenging to quantify and attribute to implementing any of the suggested changes, but conversely, implementation of the changes should not be extraordinarily burdensome on resources.  

An investment into calibration equipment and systems must be financially justified, just like any other business investment. But does a cheaper cost of purchase always mean a higher return on investment? Not necessarily. When building a business case for calibration calibration system investment, what may seem at the outset to be cheaper may not necessarily be so, if the evaluation is made from total or life cycle cost perspective instead of evaluating cost of purchase only.

As many as every fourth company in the process industry is at the moment considering to make some kind of update to its calibration process and systems. I admit, the number sounds quite high, but it is based on a specific study we recently made with the International Society of Automation (www.isa.org) concerning calibration process changes.