Pilot Study: Bilateral comparison for Volume inside a pipe prover - 120 and 60 L

Project Description

This bilateral comparison for volumes inside a pipe prover involves Kalibra OGS Services (South Africa) and VSL (The Netherlands).
VSL is the only National Metrology Institute (NMI) listed in the KCDB database for determining volumes inside pipe provers. For years, VSL has sought to establish a comparison with another NMI or Designated Institute (DI) but has been unsuccessful.

Pipe provers are large instruments that cannot be transported between participants. Therefore, the pipe prover used for comparison must remain at a fixed location, requiring participants to travel to this site to perform measurements. Kalibra OGS Services, an ISO/IEC 17025 accredited company, can perform these calibrations globally.
However, they have faced the same challenge of finding a partner for comparison until now.

The pipe prover used in this comparison is part of the water flow facilities of VSL and placed in a laboratory environment. Kalibra OGS Services will travel to VSL and perform the measurements with their own standards and instruments at 120 L and 60 L. The reference conditions for temperature and pressure to establish the reference volume are 20 °C and 0 Pa(g).

VSL aims to use this comparison to demonstrate their claimed capabilities.

Final report 2025-11-12

The project has been completed and the report can be downloaded here>>.

The final report has been issued with the following conclusion for both the 60 L and 120 L volumes:

The comparison demonstrates that all calculated En values based on the calibrated volumes and CMCs are well within the normalised threshold of 1, confirming strong agreement between the results of VSL and Kalibra.
This outcome provides clear evidence that the measurement processes and uncertainty estimations of both organisations are robust and reliable.

The results support the validity of the claimed Calibration and Measurement Capabilities (CMCs), reinforcing the credibility of both laboratories in their respective accreditation processes