GB441924A - Improvements in or relating to pipe lines - Google Patents

Abstract

441,924. Valves. GIBBS, G. J., 7, Lune Street, Preston, Lancashire. June 29, 1934, No. 19201. [Class 135] A throttle valve 13 near the delivery end of a pipe line 10 leading from a variable stream or gathering ground to a reservoir or the like 12 is under the joint control of a pressure meter 14 and a velocity meter 15 so that the cross-sectional area available to water flow is reduced when the pressure head is reduced due to a reduction in the quantity of water available at the gathering ground. Similarly this cross-sectional area is increased as the head increases, the result being to conserve the head, and as far as possible to maintain it constant. The meters 14, 15 are in the form of stand pipes arranged on opposite sides of the valve 13 respectively, Fig. 3. Normally the levels 21 and 22, 17 and 18, and 25 and 26 corresponding to decreasing amounts of opening of the valve 13 for a normal head of water in the upper reservoir 11 would not be equal, but by arranging a liquid of heavier density, such as mercury, in the meter 14 and suitably choosing the dimensions of the Venturi throat 16 these levels may be made equal for a normal head. The levels shown in dotted lines 23, 24, 19, 20, 27, 28 correspond to a decreasing head. The velocity meter 15 is seen to be more sensitive for large flows and the pressure meter for small flows. The movements of the levels in the meters are arranged to control a reversible electric motor, or a hydraulic motor through a worm and a segmental gear. Fig. 5 shows an arrangement in which floats 33, 37 on the liquid columns operate through flexible connections 35, 38 passing over pulleys 36, 39 respectively a two-way mercury switch 34. This switch is connected by cables 40, 41, 42 to a battery 45 and electromagnets 43, 44 controlling the electric or water motor in such a way that when the float 33 descends below the float 37, the magnet 44 is energized and the valve 13 is moved towards its closed position.. To avoid " hunting," the electric or water power is supplied intermittently so that valve 13 moves step-by-step. Instead of using mercury in the column 14, the travel of the float 37 may be magnified by using two flexible connections secured to a differential drum. Fig. 7 shows in plan a mechanical arrangement for controlling the pilot valve 53 of the throttle valve motor. The floats (not shown), are connected by flexible means to brackets 48, 49 non-rotatably connected but slidable on shafts 46, 47. The bracket 48 is formed with a finger 50 continuously oscillated by a crank 70. The bracket 49 which is connected to the valve 53 has two fingers 51, 52 normally above and below the finger 50. When the float in column 14 descends below that in column 15, the finger 50 rises to the plane of the finger 51 and the valve 53 is moved so that the valve 13 is moved towards closed position. In a further modification, the pressures in pipes 14, 15 act on the faces of a differential piston operating a control valve which is maintained in neutral position so long as the head of water is normal.