Metrology 2 Flashcards
What is the NPL?
National Physics Laboratory. They measure physical quantities such as mass, length, density, time etc.
What is the NEL?
National Engineering Laboratory. They measure flow and density quantities such as gas, water, multiphase liquids.
What is the LGC?
Laboratory of the Government Chemist. The measure Chemical and Biochemical quantities such as certified reference materials and gas standards.
What is the purpose of the National Measurement and Regulation Office?
Trade Measurements • Type Approval • Equipment testing • Mass, length & volume calibration • EMC Testing
What is meant by measurement traceability?
Ability to trace the result of a measurement to a single source that is a national, or more likely, an international standard.
What is the purpose of UKAS?
United Kingdom Accreditation Service. If a laboratory wishes to become accredited to provide calibration and regular testing for companies.
Outline a basic traceability chain
NPL National Standards Secondary / Transfer Standards Working Standards Instrument or Measuring Process
Transfer standards
Typically as you progress up a traceability chain, the standard should become 10x more accurate
Why is the calibration environment difficult to control?
It is a function of temperature pressure
humidity vibration
electrostatic fields electromagnetic fields
human interaction
What can be done if the calibration requires more stability?
involve many measurements across time.
What is the BSI
The British Standards Institute generates, holds and maintains industrial standards for the UK
What is the ISO
A global organization which is driving the unification
of all national standards
What is the purpose of calibration?
to provide confidence about a measurement instrument’s accuracy and repeatability.
What is the maximum error of the calibration process?
•The error due to the calibration process
should be a maximum of ten percent (1:10) of
the permissible error of the instrument or
measuring process being calibrated – 10X
rule again.
