Abstract The diverter system is a key component in achieving a high-accuracy liquid flow rate standard using a static gravimetric system with a flying start and stop method. A new system with double diverting wings has been developed in order to reduce the diverter timing error that dominates the uncertainty in the calibration of flowmeters. The basic concept of the new system is that each wing should move in the same direction at the beginning and end of measurement. The diverter timing error has been estimated using a small prototype in a water flow circuit in order to make a comparison between the performance of the new system and those of conventional systems with a single diverting wing. The results show that the jet flow condition has little effect on the timing error estimated by the double-wing method, although the error with the single-wing system is dependent on the liquid flow rate. Therefore, the triggering of the timing system can be easily adjusted over a wide range of flow rate by using the new diverter system. Furthermore, this system is adopted for a new calibration facility for hydrocarbon flow measurements at NMIJ.