Meterology the science of measurement

Metrology:
The Science of
Measurement

www.alliancecalibration.com

A Bit About Me
Kevin 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


Metrology vs. Calibration
Metrology 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.


Calibration where you didn't
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!


Calibration where you didn't
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 didn't calibrate their
instruments they could end up producing
overcooked or worse, undercooked food
And serving raw chicken would
be very bad for business!!

How Calibration Works
Direct Comparison
2-Devices are
simultaneously
measuring the same
quantity under the
same conditions


Transfer
The use of a known
artifact (i.e. gage
block or mass) to test
a measuring device.


Intrinsic
Standards that posses
a measurable
quantity by their
nature
Triple-Point of Water
cell is 0.01°C with an
error as low as 5 mK


Traceability
Traceability 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

ISO 17025 Accreditation
ISO 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 www.alliancecalibration.com in place to
& practices
perform calibrations with confidence.

“Hands-On” Demonstration
How 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


Problems?
Straightness Frayed Edges

Pulling Force Resolution of the ruler

Lighting Conditions Eyesight

Temperature Humidity
Every measurement apparatus has limitations. These limits
impose a degree of error in every measurement made.

With more specialized equipment we can make better and
better measurements, but there will always be an element of
error based on various conditions.

Measurement uncertainty is used as a method to quantify the
error present in any measurement.

Measurement Uncertainty
All 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.

The 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.


The 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.

Calibration Tracking
In 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.


At 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.

There 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.

Long Term Trending
Plotting data over time and noting
when adjustments or repairs were
required is an excellent method to
visually represent an instrument's
history.

As more history is recorded it
becomes easy to predict when future
failures are likely.

And when anomalies occur along the
trend they become noticeable and
point to possible problems elsewhere
in the quality system.

Questions & Comments

Thank you!!

Meterology the science of measurement

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