Accurate calibration requires an instrument under test (IUT) to be compared to a calibration standard which will have an output or measurement of known value.
But where do these standard measurements come from? And how are they enforced in Australia?
A basic definition
A calibration standard is an internationally recognised value that is considered to be objectively accurate. It is the measurement which an IUT is compared against to find the margin of error and tweak the instrument back to working accurately. A very basic example could be the temperature at which water boils (100 degrees) at sea level, or the length of a meter (100cm).
This is not to be confused with a documented ‘Standard’, such as ISO9001 and ISO17025. These documented ‘Standards’ outline requirements, specifications, guidelines, or characteristics that can be used consistently to ensure that materials, products, processes, and services are fit for their purpose.
International calibration standards
The International System of Units (SI) is a set of values which are globally accepted as the undeniable standards. These cover 7 base units – the second, meter, kilogram, ampere, kelvin, mole, and candela. These standards have been based on constants in nature which will not change, for example the speed of light. Previously some, such as the kilogram and metre, were based on physical pieces of metal, however these two have evolved to be based on constants in physics.
Who upholds these in Australia?
Each country has one or more national bodies whose role is to promote and uphold the SI units. In Australia there are four bodies responsible for this role:
- The National Measurement Institute (NMI)
- National Association of Testing Authorities, Australia (NATA)
- Standards Australia
- The Joint Accreditation System of Australia and New Zealand (JAS-ANZ)
These bodies maintain the accuracy of Australian measurements and some, such as NATA, offer accreditation to companies which perform best quality calibrations using international standards. Best practice calibration will test an instrument multiple times using a standard measurement which can be traced back to the original SI units. For very accurate instruments they will only be a step or two removed from the base SI unit, lower accuracy instruments can be many steps removed, but always traceable all the way back.
Why do we need calibration standards?
Calibration standards allow us to ensure accuracy of testing and measurements around the world. Uniform measurements also allow us to use equipment safely. Without a global standard to compare to, we could risk our own wellbeing or that of our staff, especially with important safety equipment such as PPE.
How we use calibration standards
Mobile Test ‘n’ Cal are a NATA accredited lab, as well as holding SAI Global Certification for international quality and safety standards. We test and calibrate a huge range of equipment to ensure the safety and compliance of your workplace. We run above industry average number of tests in our calibrations to make sure our results are accurate and repeatable before signing them off as fit for use.
With onsite calibrations we strive to minimise disruptions to your workflow while helping you comply with safety regulations. For more information or to book your next calibration, contact us on 1300 662 119 for Australia or 0800 123 682 for NZ.