Electromagnetic flowmeters are less affected by bending pipes, and the straight pipe length requirements are far lower than other flow meters such as throttle differential pressure type and vortex type. However, because the electromagnetic flowmeter has high accuracy requirements for the measured value, the change of external installation may also have a greater impact on the measured value, so effectively improving the bending of the pipe is very important for the measurement impact. In order to reduce the influence of bending pipe on measuring fluid, in addition to increasing the front straight pipe section of the instrument, the user can also find ways to reduce the impact from the installation method.
Influence of flow velocity distribution downstream of bending pipe
Due to the centrifugal force, the fluid flowing through the bend produces diffusion effect on the outer wall and contraction effect on the inner wall, resulting in transverse flow secondary flow, resulting in velocity distribution distortion in the downstream.
At present, most electromagnetic flow sensors are designed with non-uniform magnetic field distribution structure. According to the theory of non-uniform magnetic field, in the transverse plane area of the measuring tube containing electrodes, the cutting magnetic field lines of each small liquid volume element have different "effects" on the signals between electrodes, so the magnetic field intensity of each point is not uniformly designed according to the "effect", so that the flow velocity distribution distortion will not affect the flow measurement value under ideal conditions. However, the actual meter is still affected.
