The metrological impact of the Minerva promise “ensuring carefree traceability”
For many years we live by the Minerva customer promise “ensuring carefree traceability”. But what is the metrological background and impact of this promise?
To answer this question let’s first examine what traceability means. According to the International Vocabulary of Metrology traceability means:
“Property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty”
The heart of our pressure calibration laboratory is based on piston gauges which define pressure by means of area and mess, or in other words pressure is amongst others traceable to length and mass. Let’s focus on the traceability to the basic SI quantity length.
Length / area traceability in a piston gauge is realized by means of a piston cylinder. The area combined with mass load defines the pressure range of a piston cylinder.
Our largest piston cylinder has a diameter of 50 mm, our smallest piston cylinder has a diameter of 1,6 mm and we have a total of 17 piston cylinders to cover the range of 0,001 Pa till 500 MPa.
All piston cylinders are regularly calibrated at an ISO/IEC 17025 accredited laboratory who maintains their traceability to length by means of a so-called calibration chain.
The light blue and green rectangulars represent piston cylinders from the accredited laboratory where we outsource our piston cylinders. The arrowed lines represent comparisons between the individual piston cylinders. As you can see there are two inputs from external references; one at the 5 kPa/kg and one at the 2 MPa/kg reference where the 5 kPa/kg one is the direct traceability to length.
The scheme above assures that any deviation in metrological characteristics of one of the piston cylinders is detected. When we send one of our piston cylinders out for calibration, it is connected to the calibration chain and linked via an unbroken chain to the meter and thus we comply to the VIM definition of traceability.
I hope I have shone light on the metrological background and impact of traceability as an important part in the Minerva customer promise. If you have any questions, feel free to contact me!
Carel Adolfse
Technical Director
carel.adolfse@minerva-calibration.com
Links to reference documents:
April 15, 2024