MIKES-Kajaani CLEEN MMEA Certainty Seminar Petri Koponen Group manager

Content Importance of metrology What is calibration During calibration Examples of drift Use of a calibration certificate Examples of adjustment Facts about calibration Petri Koponen

Importance of measurement Every new technology or science breakthrough, industrial development, or commercial success depends on one form of measurement or another. Today, we practically measure everything we encounter: the weight of our food, the volume of our fuel, the distance between two points, temperature, pressure, humidity, light, current, voltage, power, speed, energy, etc. In Europe 2 % of GDP is used for measuring Dr Brian R. Bowsher 2009, NPL 40 % EU directives include measurements The OECD has estimated that about 80 % of global merchandise trade is affected by standards or by regulations that embody standards. Petri Koponen

What is calibration Calibration is a comparison between measurements The device with the known or assigned correctness is called the standard. The second device is the unit under test. In order that an instrument or artefact (unit under test) should accurately indicate the value of a quantity, the instrument or artifact requires calibration. This procedure is essential for establishing the traceability of the instrument or artefact to a primary standard. Quality of the instrument under calibration is not a concern; all instruments can be calibrated. Petri Koponen

What is calibration The formal definition of calibration by the International Bureau of Weights and Measures is the following: "Operation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties (of the calibrated instrument or secondary standard) and, in a second step, uses this information to establish a relation for obtaining a measurement result from an indication. JCGM 200:2008 International vocabulary of metrologyJCGM 200:2008 International vocabulary of metrology Petri Koponen

Calibration instruments Petri Koponen Distinction between instrument and artefact in general: An instrument measures a quantity An artefact provides a quantity For example, a digital multimeter (DMM) is an instrument that measures voltage, resistance or current and displays it as a number. An instrument may also measure a quantity by means of the position of a pointer or dial.

During calibration During calibration, a value measured by an instrument or provided by an artifact is compared with that obtained from a standard instrument or artefact. If there is a difference between the values as indicated by the instrument or the artefact and corresponding standard, then the difference between these two is a quoted as a correction to the instrument or artefact. This process is referred as calibration, and the correction always has a stated associated uncertainty Petri Koponen

Why recalibrate The values indicated by an instrument or provided by an artifact can drift over time. This makes recalibration necessary. Manufactures advice that calibration should be carried out at regular intervals (every 12 months or so) Petri Koponen

Change of zero value, 1 MN transducer nr Petri Koponen

Rel. change of the sensitivity, mean values from RP measurements, 1MN transducer nr Petri Koponen

Abs. change of the sensitivity, 1MN transducer nr Petri Koponen

Rel. change of the sensitivity, 1MN transducer nr Petri Koponen

Use of calibration certificate Calibrations are done by the calibration guidelines. Can be a standard Can be an approved method Can be a done as customer requires Every calibration certificate which is not used as a tool is misused End user can follow how the measurement device behaves over time (conditions, measurement uncertainty etc.) Adjustment is not part of the calibration However, it could be done After the adjustment the measurement instrument must be recalibrated Petri Koponen

Facts Measurement without calibration is only guessing! Calibration without traceability is only cashing in Without traceability, there is no way to ensure that a measurement made by an instrument is accurate. Petri Koponen

Thank you !