GB752822A - Improvements in rate of flow meters, especially for liquids - Google Patents

Abstract

752,822. Electric indicating systems. OFFICE NATIONALE D'ETUDES ET DE RECHERCHES AERONAUTIQUES. O.N.E.R.A. March 11, 1954 [March 12, 1953], No. 7088/54. Class 40(1) [Also in Groups XXVI, XXIX and XL(b)] A fluid rate of flow meter comprises a conduit through which all or part of the flow to be measured passes a venturi in the conduit, a meter wheel is pivoted about an axis at right-angles to the direction of fluid flow and tangential to the venturi throat, the meter wheel having a maximum radius smaller than the diameter of the venturi throat and having no mechanical connection with the outside of the conduit, and photo-electric means for indicating the effect of flow variations in the conduit on the meter wheel. One form of flowmeter, Fig. 1, comprises a venturi sleeve 3 fitted within the conduit 1 and a four-bladed meter wheel 2 which is pivoted about an axis 6. A casing 11, attached to the conduit 1 contains a light source 12 from which a beam is directed through a window 9, in a recess 7, and is reflected from the edge of each blade of the wheel as it passes the window, the reflected beam falling on a photo-multiplier 16 for indicating the speed of rotation of the wheel. The wheel 2 may be of stainless steel or of tetrafluorethylene resin with, as shown in Fig. 4, the ends of each blade drilled to take a stainless steel wire 23 which is then cut to form a reflecting surface 20. In a second form, Fig. 3 the velocity of fluid flow is increased by means of a double conical body 4 and the wheel is fitted at the throat of the annular venturi so formed. The ratio of the minimum and maximum diameters at the throat is preferably 0.2 and the apex half-angles of the convergent and divergent portions are preferably 14 degrees and 7 degrees respectively.