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Meterology the science of measurement


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Meterology the science of measurement

  1. 1. Metrology: The Science of Measurement
  2. 2. A Bit About MeKevin Radzik with Alliance Calibration ASQ CCT since 2009 Technical Manager P&T(Process & Test) 10+ Years in the Pharmaceutical Industry • Working “in-house” to manage calibration programs • Contractor providing calibration & control services to the pharmaceutical industry
  3. 3. Metrology vs. CalibrationMetrology is the science of measurement. Metrology includes all theoretical and practical aspects of measurement.“Metrologia” in ancient Greek meant the “Theory of Ratios”Calibration is the comparison of a “standard” of known accuracy to an artifact of unknown accuracy.
  4. 4. Calibration where you didnt know it existed...Items like deli scales and fuel pumps are calibrated and certified by local government agencies to protect customers.With gas at $4/gallon they make sure you are getting what you pay for!
  5. 5. Calibration where you didnt know it existed...Restaurant chains develop recipes in laboratories and refine them to be used in their restaurants in the simplest method possible. For example deep fry for 3:00 minutes.If the laboratory didnt calibrate their instruments they could end up producing overcooked or worse, undercooked food And serving raw chicken would be very bad for business!!
  6. 6. How Calibration WorksDirect Comparison2-Devices are simultaneously measuring the same quantity under the same conditions
  7. 7. How Calibration WorksTransferThe use of a known artifact (i.e. gage block or mass) to test a measuring device.
  8. 8. How Calibration WorksIntrinsicStandards that posses a measurable quantity by their natureTriple-Point of Water cell is 0.01°C with an error as low as 5 mK
  9. 9. TraceabilityTraceability is established by an unbroken chain of comparisons to a NSI (National Standards Institute)Each level of comparison will add to the error of the measurement performed
  10. 10. ISO 17025 AccreditationISO 17025 was developed to standardize the way in which laboratories perform and report calibration and testing data.ISO 17025 accreditation bodies such as LAB, A2LA, NAVLAP, A-CLASS, ANAB and others ensure compliance to the standard. Accreditation bodies recognized by ILAC are all considered equivalent.Accreditation is good assurance that a lab has the proper tools in place to & practices perform calibrations with confidence.
  11. 11. “Hands-On” DemonstrationHow long is a piece of string On each table there is a calibrated ruler and several pieces of string. Please take a moment and work together to attempt the most accurate measurement of a “piece of string” possible
  12. 12. Problems?Straightness Frayed EdgesPulling Force Resolution of the rulerLighting Conditions EyesightTemperature HumidityEvery measurement apparatus has limitations. These limitsimpose a degree of error in every measurement made.With more specialized equipment we can make better andbetter measurements, but there will always be an element oferror based on various conditions.Measurement uncertainty is used as a method to quantify theerror present in any measurement.
  13. 13. Measurement UncertaintyAll sources of error in a given measurement must be quantified, and accounted for.The number sources of error can be as few as: accuracy of the standard, uncertainty of the standard, resolution and repeatability.However other items can also influence the measurement, such as: temperature, temperature Δ, barometric pressure, altitude, humidity, and the uncertainty of whatever instruments are used to measure these.
  14. 14. Measurement UncertaintyThe ISO document “Guide to the expression of Uncertainty in Measurement” (the GUM) defines the way in which measurement uncertainty is calculated.Contributing factors are quantified and corrected to represent 1σ using divisors based on the type of contribution the error provides.
  15. 15. Measurement UncertaintyThe normalized contributors are then combined using the “Root of the Sum of Squares” and multiplied by a confidence factor.The confidence factor of k=2 is most commonly used, and provides an approximately 95% assurance that the true value of the measurement is reported within the limits of the measurement uncertainty.Measurement uncertainty defines the “gray area” inside of which the true value of a measurement lies.
  16. 16. Calibration TrackingIn the short term calibration provides a reasonable assurance that an instrument is fit to be used for the task for which it was designed.However, long term evaluation of calibration data can provide increased confidence or even predict when a device is likely to “drift” out of specification under normal use.
  17. 17. Calibration TrackingAt Alliance Calibration we provide our customers free access to our eTracking system as an easy way to keep all your calibration data in one easy to use web site.
  18. 18. Calibration TrackingThere are several additional products available to track calibration data, the important thing is to use the tool that works for you.In many industries calibration cycles are mandated by standards, but in industries where they are not long term trending of calibration data can be valuable in determining calibration cycles to be the most cost effective.
  19. 19. Long Term TrendingPlotting data over time and notingwhen adjustments or repairs wererequired is an excellent method tovisually represent an instrumentshistory.As more history is recorded itbecomes easy to predict when futurefailures are likely.And when anomalies occur along thetrend they become noticeable andpoint to possible problems elsewherein the quality system.
  20. 20. Questions & Comments Thank you!!