Abstract: A system for separating gas from a liquid flow whose volume is to be measured with the exclusion of gas inclusions comprises a liquid conduit (5) through which the liquid flow is conducted. The conduit (5) incorporates a volume meter (5), a fluid homogeneity meter (20, 21) arranged upstream of the volume meter, a closure valve (6; 60) and a gas discharge conduit (7; 71) connected to the liquid conduit. The fluid homogeneity meter is constructed to hold the valve (6; 60) in its valve setting in which the liquid conduit (5) is open when the difference between the gas contents of the liquid detected at different time points is lower than a predetermined limit value, and to close the valve (6; 60) when these difference values are not beneath the limit value. The arrangement can be used, for instance, with a system for emptying oil products from a tank in a petroleum tanker.