A method for analyzing the reliability of a measured volumetric flow rate of a fluid in a gas outlet line of a gas-liquid separator is provided. In one embodiment, analyzing the reliability of the measured volumetric flow rate includes measuring a gas volume fraction of the fluid in the gas outlet line, comparing the measured gas volume fraction of the fluid to a threshold gas volume fraction level, and determining whether the measured volumetric flow rate of the fluid is reliable based on the comparison. Additional systems, devices, and methods are also disclosed.