A transportable refractometer for assessment of kPa pressures with ppm level precision is presented. It is based on the GAs MOdulation Refractometry (GAMOR) methodology, making it resistant to fluctuations and drifts. At the National Metrology Institute at RISE, Sweden, the system assessed pressures in the 4.3 - 8.7 kPa range with sub-ppm precision (0.5 - 0.9 ppm). The system was thereafter disassembled, packed, and transported 1040 km to Umeå University, where it, after unpacking and reassembling, demonstrated a similar precision (0.8 - 2.1ppm). This shows that the system can be disassembled, packed, transported, unpacked, and reassembled with virtually unchanged performance.
This project (QuantumPascal, 18SIB04) has received funding from the EMPIR programme co-financed by the Participating States and from the European Union's Horizon 2020 research and innovation programme. The authors acknowledge supportfrom the Swedish Research Council (VR) (ProjectNo. 621-2015-04374); the Umeå University Industrial Doctoral School (IDS); the Vinnova MetrologyProgramme (Project Nos. 2018-04570 and 2019-05029); and the Kempe Foundations (Project No.1823, U12).