part 1 traceability introduction[1]
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June 2004 slide 1
Calibration basics
Kjell BerghNemko
June 2004 slide 2
What is calibration
Relate measurement to SI unitsTraceabilityProof of functionality
Known uncertaintyUncertainty of calibration processAccepted deviation of instrument to ”true” value, Tolerance level
StandardsWhat is a standard?
June 2004 slide 3
Traceability
StandardsStandard vs. standard ! (Physical object vs. document)
SI-unitsInternational standardsNational standardsSub-standardsTertial standardsLower-level standards
June 2004 slide 4
SI units
Basic unitsMass (Kilogramme = kg)Length (Meter = m)Time (Second = s)Electric current (Ampere = A)Temperature (Kelvin = K)Luminance (Candela = cd)Molecular mass (mol)
Derived unitsFrequency (Hertz = Hz = s-1)Force (Newton = N = m*kg/s2)Pressure (Pascal = pa = N/m2)Energy (Joule = J = N*m)Power (Watt = W = J/s)Electric charge (Coulomb = C = A*s)
Derived unitsElectric potential (Volt = V = W/A)Capasitance (Farad = F = A*s/V)Inductance (Henry = H = V*s/A)Resistance (Ohm = Ω = V/A)Conductance (Siemens = S = A/V)Magnetic flux (Weber = Wb = V*s)Magnetic induction (Tesla = T = Wb/m2)Light flux (Lumen = lm = cd*sr)Light intensity (Lux = lx = lm/m2)
June 2004 slide 5
Accreditation
Calibration labISO 17025
QA-system of organizationPersonell ProceduresInternal surveillanceScope of accreditation
June 2004 slide 6
QA-system
Certified to ISO standard 17025Management, command structurePurchase handlingAssignment handling, billingObject reception and deliveryObject handling during calibrationPersonnel training and competenceProcedure maintenance, update
June 2004 slide 7
Personnel
QA-systemEducational standardCompetence maintenance, trainingIntegrity, independence of economic factors
PersonnelResponsibilityProcedure loyality
June 2004 slide 8
Procedures
Step-by-step for measurement set-upEnvironmental conditions (temp, ventilation,vibration, etc.)Acclimatization of calibration objectCalibration status of control instruments/standardsStep-by-step performance of measurementCompetence of personnel
June 2004 slide 9
Internal surveillance
QA-systemInternal proceduresPreventive actionsRegularity
June 2004 slide 10
Scope
Basic unitsList all units with accredited certificate
Derived unitsDocument how these may be derived from basic unitsHow this is related to accreditation
Objects for calibrationAre the important parameters covered by accreditation?How much can one rely on the basic accreditation?Let Cal.lab. document how non-accredited parameters can be covered by the general accreditation.
June 2004 slide 11
UncertaintyCal. object
May show small/acceptable deviation from ”true” valueStabilityParameter dynamic rangeSystem noise influenceImpedance mismatch
Cal. lab.Uncertainty of used sub-standardsUncertainty of cal. procedure
Influence of environmentInfluence of operatorInfluence of method
June 2004 slide 12
External vs. in-housecalibration
Specialized calibration labAccreditation costCompetenceEquipmentTraceabilityEfficiency
In-houseLess transportation costLess time delayExpenses to maintain
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