Patent GB-937769-A (GB)
Title: Improvements relating to apparatus for recording the flow of liquids in open channels
IPC: G01F1/00
Filed: 1960-10-22
Abstract: 937,769. Flowmeters. CONSERVATORS OF THE RIVER THAMES, and W. GREEN. Oct. 23, 1961 [Oct. 22, 1960], No. 36328/60. Addition to 888,366. Class 69 (1). A gradometric flow-recorder according to the parent Specification measures flow through an open channel according to the Chezy formula Q=CA#mi, where Q is the rate of discharge; C a constant; A the cross-sectional area of the channel, m its mean hydraulic depth and i the hydraulic gradient. The construction claimed comprises adjacent stilling wells opening into the channel upstream and downstream, the difference of levels in which actuate a differential mechanism to feed a displacement which is a function of #i to one input of a multiplying mechanism, to a second input of which a depthfollowing mechanism feeds a displacement which is a function of CA#m. The differential displacement for #i is manifested as a linear movement of a carrier carrying cable drums connected to floats in the stilling wells. In the present Specification, which is a Patent of Addition to the former, the differential displacement for #i is manifested as an angular movement of a pivoted carrier shown in end view in Fig. 3 and side view in Fig. 4. The carrier has end plates 46 and 47 spaced between rods 53, 54, 55 and supports on spindles 56 and 57 respectively helically grooved main drums 58 and 59 fixed beside counterweight drums 60 and 61, all drums being connected by spur gears 62, 63, 64, 66 so as to rotate together. Light chains or wires 68 and 69 are led off parallel from the main drums 58 and 59 and over pulleys to connect with floats in the upstream and downstream stilling wells respectively (Figs. 1 and 2, not shown). A single chain 72 runs from one counterweight drum 60 around a pulley on a weighted block 73 and back to the other drum 61. The carrier is pivoted at 49 and 50 between U-plates 48 fixed to a main frame of girders 27 to 33 connected by cross-pieces 36 to 42. Equal rise and fall in the upstream and downstream levels causes the chains 68 and 69 to turn the drums 58 and 59 without pivoting the carrier ; unequal rise and fall will cause the carrier to tilt through an angle which is a function of i as defined above as well as turn the drums. A chain 92 connected to a float in a third stilling well which opens into the mid-part of the channel causes a drum 91 to turn against a counterweight (not shown) on a chain 93 when the level in the well changes. A shaft attached to the drum 91 turns a cam 90 which causes a follower 89 to move in proportion to the term C<SP>2</SP>A<SP>2</SP>m as formerly defined. The quantity i is fed to the multiplying mechanism by an arm 76 which has one end pivoted to the U-plate 48 at A in alignment with the pivots 49 and 50 of the carrier and the quantity C<SP>2</SP>A<SP>2</SP>m by a link 88 pivoted to the cam-follower 89. The other links of the multiplying mechanism comprise an arm 81 which is rigidly fixed to a pen-arm 97 and to the ends of which are pivoted at C to a link 80, counterbalanced at 79, and at E to an arm 82 of a bell-crank lever 82-83 which is pivoted on a frame-member at D. The arm 76 is pivoted to the other end of the arm 80 at B and the link 88 to the arm 82 intermediate of its end pivots D and E. The arm 82 and the link 80 are each the same length as the length of the arm 76, which is also the distance apart of the fixed pivots A and D. The arm 81 is half the same length. A drum 86 revolves on a spindle mounted on a bracket 84 on the bellcrank lever 82-83, so that the drum 86 moves with the lever 82 with respect to the pen-arm 97. In consequence of this mechanism it can be arranged that when the arm 76 is in its " zero " position in respect of the quantity i, the pivots A and C coincide; when the arm 82 is in its " zero " position with respect to the quantity C<SP>2</SP>A<SP>2</SP>m, the pivots B and D coincide and that in all other positions of the arms the pen moves over a chart on the drum 86 proportionately to the quantity C<SP>2</SP>A<SP>2</SP>mi. By using square-root paper the quantity Q=CA#mi can be read direct from the chart.