Impeller arrangement in a measuring device

摘要

The invention relates to an impeller (1) being rotated around an axis (2) for a mass flow measuring device receiving inflow of material through an inlet tube (10). To improve the measurement accuracy, the fan character of the impeller is reduced. This is obtained by two design principles which can be combined. The impeller comprise of a number of mainly radially directed vanes (6). That side of the vanes along which the measured material flow is flowing, is formed as a duct (8,9) with a cross area (6a) which is constant or decreasing in the direction from the centre of the impeller. The other principle is to reduce the airflow by putting an upside down turned bowl over the impeller. <IMAGE>