Rockwin Oil Calibration Rig is based on transfer standards in accordance with API Codes and currently has a maximum range of 300 LPM. The principle of calibration is comparison of flow volumes registered by the master meter and the meter under test. The rig has been designed by Krautler GmbH, Austria, who have also supplied all the key components. The master meters are certified by Swedish National Testing and Research Institute. Hydraulic Oil is used as the calibration medium.