Select the reference standards for the type of device to be calibrated. Take the readings from the instrument that has to be calibrated. Derive a relation between standard values to that of the readings taken and obtain a curve based on the readings.
Obtain the correction of the measurements by considering the inverse values of the curve plotted. STEPSOF CALIBRATION Indicative – It is calculated by considering the titration of the chemical reaction between the standard solution and the analyte. EDM- Extrapolative Dilution Method EISM- Extrapolative Internal Standard Method IEM- Indirect Extrapolative Method CEM – Conventional Extrapolative Method Extrapolative – There are four different types of methods in this type IDM- Interpolative Dilution Method IISM- Interpolative Internal Standard Method IIM- Indirect Interpolative Method CIM – Conventional InterpolativeMethod Interpolative – There are four different types of methods in this typeMETHODSOF CALIBRATIONExample:- In medical field, toperform a culture test, the instrument has to be calibrated by removing thepressure by creating vacuum and also the low temperature is obtained beforeperforming the test. If the calibration is not done properly, the accuratevalues cannot be obtained which results in the failure of test. Temperature Pressure Friction HumidityFACTORS AFFECTINGTHE CALIBRATION Accuracy – It is nothing but the exactness in result which is expressed in percentage. Tolerance – It is the maximum percentage of the error accepted. CHARACTERISTICSOF CALIBRATIONLet’sassume that you have performed an experiment and that you have done it withoutcalibrating your instruments and submitted the values to the supervisor.
Afterthat the supervisor repeats the experiment and finds out that the values werewrong and this makes you to lose your credibility. IMPORTANCE OFCALIBRATION· Hysteresis Calibration Error – This error occurs when theinstrument tends to react differently to the increasing value of input incomparison to the decreasing value of input. These errors are almost caused dueto the mechanical friction between the parts of the instrument such as gears,levers, pulleys, etc.
· Linearity Calibration Error – It affects the responsefunction of the instrument in such a way that the error will no longer be in astraight line. The way of appearance of linearity error is unique for each andevery instrument. If this error cannot be calibrated, the average of maximumand minimum errors has to be taken so that the range of error goes to minimalvalue. b = Zero adjustment x = Input m = Span adjustment y = Output Where, y = mx + bThe linearequation to calculate the output by calibrating span and zero errors · Zero Shift Calibration Error – It shifts the graph verticallywhich affects the zero adjustment error and it effects all the pointssimilarly. The percentage of error is equal across the entire range of values.· Span Shift Calibration Error – It effects the slope of thegiven function. The effect of error varies from one point to another point.TYPES OF ERRORS· Forsome of the instruments, the manufacturer indicates that the instrument has tobe calibrated after the given number of uses.
· Someof the experiments require calibrated certificates for the instruments beforeit is used.· Theinstrument has to be calibrated if the data obtained is questionable or if theinstrument user suspects any chance of mistake in its values.· Theinstrument has to be calibrated if it had any incident by any chance such asfall down, hit by another instrument, etc.· Aftermeasuring the data, the instrument has to calibrated so as to know whether thedata collected is reliable or not.· Beforemeasuring any data, the instrument has to be calibrated.WHY IS CALIBRATION NEEDED?Itcan be defined as the process of making the corrections in readings of theinstrument by taking the readings from that instrument under the specificderived conditions and comparing them with the known values of the instrument.The definition could be simplified as that the calibration is the comparison ofthe values of the given instrument to that of the standard one.
The definitionalso implies that the value to be attained with zero tolerance. Sometimes, manynumber of iterations are to be performed on the instrument to obtain the valueof error and their average is taken when the instrument cannot be calibrated. CALIBRATION