What is Calibration?

What is Calibration?
In the industry and the use of process instrumentation equipment, periodic calibration and maintenance is required to ensure its proper operation from the simplest to the most complex. Drift, environmental factors, the power supply, the addition of equipment to an output loop, and process changes all cause process instrumentation equipment to lose its accuracy. Only by calibrating that tool can we be sure. Calibration is a comparison between two devices. The first is a single instrument that must be calibrated on the basis of a specific unit of measurement, often referred to as calibrated equipment, and the second is a calibrator set that is fixed to a well-known standard.

Calibration of an instrument involves examining several points over a range of the instrument's measuring range or measuring equipment. After checking the accuracy of the device under test, adjustments can be made to achieve the desired accuracy.

Calibration standards Calibration
standards include any source that can provide a known reference in which the accuracy of an instrument can be compared. Calibration standards can be very different. Calibrators can include solutions that are prepared at a specific pH for calibration of pH meters, or they can contain blocks of precise thickness with which one meter can be calibrated.
Not all standards are created the same. While all standards have known accuracy, some of them are known as the core standard, which is the highest level of accuracy for a particular parameter. Early standards have been achieved with high accuracy by relying on measurement technologies using basic physical constants that do not drift. For example, the amount of volts is defined by the Josephson Effect, which has an accuracy of 1 part per billion. These constant values ​​minimize uncertainty, and make early standards the most accurate calibration tool.
Although the accuracy of calibrators varies greatly depending on the model and measurement parameters, they are roughly divided into three groups:

Industrial standards are also known as field standards. As a general rule, they are 4 times more accurate than calibrated instruments, although this scale factor can vary from industry to industry. Not useful in a laboratory.
Secondary standards are also known as laboratory standards, are more accurate than field standards, and are used to calibrate field standards.

Initial standards have the highest calibration accuracy. Primary standards are used to calibrate secondary standards.

Traceability
To improve calibration quality to acceptable levels for external organizations, it is generally desirable that subsequent calibrations and measurements be traceable to internationally recognized standards. Traceability is determined by formal comparison with a standard that is directly or indirectly related to national standards (such as NIST in the United States), international standards, or valid reference materials.