Calibration | importance of calibration | Methods of calibration

Here we learn about what is calibration and importance of instrument calibration in Measurement and also methods of Calibration.

Calibration

~ Every measuring instrument must be reliable. The results obtained must be closer to the actual values.

Calibration is the process of establishing the reliability of a measuring instrument.
~ This involves the comparison of the instrument to be calibrated with, either primary standard, secondary standard or a known input source.

~ For example, a flow-meter can be calibrated by either comparing it with a standard now measuring facility, with another flow-meter of a known accuracy or directly by allowing a known quantity of water through the meter and recording the time elapsed.

Importance of Instrument Calibration in Measurement:

~ It is the act or result or quantitative comparison between a known standard and the output of the manipulation measuring system particular variable or quantity within the desired range under measurement.
~ Every measuring instrument must be reliable that means the results obtained must be closer to actual value. Calibration is the process of establishing the reliability of a measuring instrument.
~ The calibration of all instruments is important since it affords the opportunity to check the instrument against a known standard thereby helping in evaluation of errors and accuracy.

Methods of Calibration :

The different methods of calibration are as follows :
(i) Primary calibration:
~ When a measuring system is calibrated using primary called primary standards,
calibration. The system calibrated so can be used as a source for secondary calibration for other systems.
~ The examples of primary calibrated systems are standard resistor, standard cell, etc.
(ii) Secondary calibration:
~ When a system that has been calibrated using primary standard is used to calibrate another device, then it is called secondary calibration.
~ Obviously the secondary calibration systems general purpose labs and are used for industries.
iii) Direct calibration :
~ Direct calibration is the process of calibrating a system with a known input source.
~ Direct calibration - gives the accuracy similar to primary calibration. Hence, directly calibrated for secondary used systems can also be calibration.
(iv) Indirect calibration :
~ Indirect calibration is based on the equivalence of two different devices that can be used to measure a physical quantity.
~ It is possible to carryout indirect calibration and predicts the performance of one meter based on the study of the other. Hence a small meter can be used-to determine the discharge coefficient of large meters.

v) Routine calibration :

~ It is the periodic checking of the accuracy and proper functioning of an instrument with
known standards. This includes :
(a) Visual inspection of the system.
(b) Checking for proper installation.
(c) Zero setting of meters.
(d) Proper leveling.
(e) Operational tests. (iv) Indirect calibration :
~ Indirect calibration is based on the equivalence of two different devices that can be used to measure a physical quantity.
~ It is possible to carryout indirect calibration and predicts the performance of one meter based on the study of the other. Hence a small meter can be used-to determine the discharge coefficient of large meters.

v) Routine calibration :

~ It is the periodic checking of the accuracy and proper functioning of an instrument with
known standards. This includes :
(a) Visual inspection of the system.
(b) Checking for proper installation.
(c) Zero setting of meters.
(d) Proper leveling.
(e) Operational tests.