A device for measuring flow rates (F L , F G ) of a fluid medium in a milk line, containing a first fluid (G) and a second fluid (L), wherein the first fluid (G) is a gas and the second fluid (L) is a liquid, the device comprising: a conduit configured to receive and transport the fluid medium through a measurement section (M), a first sensor device (S1) arranged in the measurement section (M), and configured to register a first measure (m1) as a speed of the fluid medium; a second sensor device (S2) arranged in the measurement section (M), and configured to register a second measure (m2) as a pressure drop over a well-defined conduit segment of the measurement section (M), the second measure (m2) being independent from the first measure (m1), the first and second measures (m1 ; m2) both being dependent on a flow (F G ) of the first fluid (G) and flow (F L ) of the second fluid (L) in the fluid medium; a third sensor device (S3) arranged in the measurement section (M), the third sensor device (S3) being configured to measure an electrical conductivity of the fluid in the measurement section (M) and based thereon derive a third measure (m3) representing an estimated ratio between an amount of the first fluid (G) and an amount of the second fluid (L) in the measurement section (M); characterized by a processor configured to derive the flow rate (F G ) of the first fluid (G) and the flow rate (F L ) of the second fluid (L) based on the first, second and third measures (m1, m2, m3) by using the first measure (m1) and the second measure (m2) for fluid flow rates above or equal to a threshold flow rate and using the first measure (m1) and the third measure (m3) for fluid flow rates below the threshold flow rate. a conduit configured to receive and transport the fluid medium through a measurement section (M), a first sensor device (S1) arranged in the measurement section (M), and configured to register a first measure (m1) as a speed of the fluid medium; a second sensor device (S2) arranged in the measurement section (M), and configured to register a second measure (m2) as a pressure drop over a well-defined conduit segment of the measurement section (M), the second measure (m2) being independent from the first measure (m1), the first and second measures (m1 ; m2) both being dependent on a flow (F G ) of the first fluid (G) and flow (F L ) of the second fluid (L) in the fluid medium; a third sensor device (S3) arranged in the measurement section (M), the third sensor device (S3) being configured to measure an electrical conductivity of the fluid in the measurement section (M) and based thereon derive a third measure (m3) representing an estimated ratio between an amount of the first fluid (G) and an amount of the second fluid (L) in the measurement section (M); characterized by a processor configured to derive the flow rate (F G ) of the first fluid (G) and the flow rate (F L ) of the second fluid (L) based on the first, second and third measures (m1, m2, m3) by using the first measure (m1) and the second measure (m2) for fluid flow rates above or equal to a threshold flow rate and using the first measure (m1) and the third measure (m3) for fluid flow rates below the threshold flow rate. <EOS>