Patent ID: 6009763
Filing Date: 2000-01-04
Classification: F24F,G01F

Abstract:
A flow sensor, having an impeller which is suspended for free rotation in a tube section and which comprises a central core and a number of blades extending from the core, wherein at least one blade extends from the core to adjacent an inner wall of the tube section, wherein measuring means are included for measuring the number of revolutions of the impeller per unit of time, and wherein the flow sensor is adapted to register a calibration speed of the impeller associated with a calibration flow rate by a measuring means, wherein a blade angle in at least a series of cross sections of the blade substantially meets the formula[tg(H(r))*Caldeb*C]/[r*D.sup.2 ]=Calrevwhereinr=distance section relative to the center of the core (m);H(r)=blade angle of section at distance r (.degree.);Caldeb=calibration flow rate (m.sup.3 /h)Calrev=calibration speed (rev/min)D=diameter tube section (m)wherein 0.003<C<0.004 and C is preferably 6.67/1974.