Patent ID: 6532828
Filing Date: 2003-03-18
Classification: G01F,G01P

Abstract:
A device in a meter for flow measurement, said meter comprising:a casing (1) which is made of a material having a known function of thermal expansion and through which a fluid passage (2) extends, two transducers (5, 6) which are arranged acoustically opposite each other on a transducer mounting (3, 4) each and which are each adapted to repetitively transmit, essentially along a sound line (l) and over a distance (Lu) between said transducers (5, 6) towards the opposite transducer (5, 6), sound pulses in a fluid which in a direction (a) flows through the fluid passage (2), and to receive sound pulses from the opposite transducer (5, 6) after passing through the fluid, an electronic and calculation unit (7) which is connected to said transducers (5, 6) for excitation and reading thereof and which is adapted to calculate, by means of the transit times (t1, t2) of the sound pulses over the distance (Lu) between said transducers both concurrently with and countercurrently to the direction of flow (a) of the fluid, at least one of a volume, mass flow and a velocity of flow (v) of the fluid through the fluid passage (2), and a compensating means (8, 9) provided in the extension of the sound line (l) and is arranged between at least one of the transducer mountings (3, 4) and the associated transducer (5, 6), said compensating means (8, 9) being made of a material having a known function of thermal expansion, wherein a length of the fluid passage in the direction of the sound line (l) dimensional changes due to a temperature change of the fluid in the fluid passage (2), said dimensional change comprising a longitudinal change of the distance (Lb) between the transducer mountings (3, 4), the longitudinal change is essentially compensated for by an opposite longitudinal change, caused by the same temperature change, of the compensating means (8, 9).