GB1272124A - Systems for measuring flow volume of a liquid flow - Google Patents

Abstract

1,272,124. Selective signalling. L.K.B. PRODUKTER A.B. 12 Aug., 1969 [12 Aug,. 1968], No. 40354/69. Heading G4H. A liquid flow measuring system of the type in which a gas bubble is introduced P, Fig. 1, into the liquid and detected A at a fixed distance downstream to initiate the introduction of a further bubble and to add unity to a counter R, is characterized in that a further detector B is provided downstream from the first and used, in conjunction with the first, to prevent spurious bubbles in the liquid causing errors. In the first embodiment, Fig. 1, bubbles have to be detected simultaneously at the two detectors A, B in order to cause the introduction P of a further bubble. In a second embodiment, Fig. 2, a third detector C is added and bubbles have to be detected simultaneously at at least two of the three detectors A, B and C to cause the introduction P of a further bubble. This embodiment also includes a detector D adjacent the point of introduction of gas, which is used to turn off the supply of gas when a bubble extends from the point of introduction P up to the detector D. This embodiment is self-starting. In a third embodiment, Fig. 3, in addition to requiring the simultaneous detection of bubbles at two detectors A and B a further detector E is provided and the supply of gas P is kept on whilst the trailing edge of a bubble passes from detector E to detector A. This arrangement ensures that the length of liquid between two adjacent bubbles will be constant (equal to L-L, as shown) irrespective of how much the bubbles actually expand within the liquid due to pressure variations. This embodiment also is self-starting, and it also includes a further detector F so arranged that if a bubble is not introduced into the liquid when it should have been the flow of liquid is turned off 16 and a lamp 17 is extinguished.