Patent GB-681132-A (GB)
Title: Improvements relating to dry gas meters
IPC: G01F3/22
Filed: 1950-05-30
Abstract: 681,132. Dry gas meters. METROPOLITAN GAS METERS, Ltd., PEARCE, W. F., and DIGGLE, S. Jan. 31, 1951 [May 30, 1950], No. 13522/50. Class 54. A dry gas meter is divided by a valve plate 1, Fig. 1, into an inlet gas compartment 6 and an outlet gas compartment 7, the arrangement being such that the gas passes from the compartment 6 to the measuring chambers and thence to the compartment 7 by way of valves actuated from the measuring chambers. Two pairs of measuring chambers D, E and F, G are each provided with a diaphragm 23 the displacements of which cause oscillation of a flag shaft 41 connected by linkage 42, 43, Fig. 3, with an adjustable-throw crank 44. The shaft 45 of this crank carries two further angularly-displaced cranks connected by links 46, 48 with two valves 27, 28 respectively. The angular interval between the two cranks causes the valves 27, 28 and the pairs of measuring chambers they control to be operated out of phase. Each valve is guided in its movement over its valve grid 25 or 26 by a slotted bar 29 which receives two -pins 30, 31 secured to each valve body. Each valve grid has two ports 35,37 communicating with the opposite sides of a diaphragm and a central port 36 communicating with the compartment 7 so that a transfer port (not shown) in each valve connects the opposite sides of the diaphragm alternately to .exhaust while the uncovered port 35 or 37 allows gas to flow from the inlet compartment 6 to the measuring chambers. A space 14 formed by a partition 8 at one side of the valve plate 1 and connected by a port 13 with the compartment 7 allows gas to pass from the latter to the exhaust conduit 12. A similar conduit (not shown) at the opposite end of the meter connects the compartment 6 with the gas supply. The meter casing is in three parts A, B and C, the upper two.of which.are formed with marginal recesses 3, 5 to receive the upper edges of the lower two members. Gaskets, for example of leather, may be used at the joints. The part C is held in place by nuts on bolts 61 which have hexagonal flanges part way along their length and are threaded into bosses 62 into the port A to secure the latter to part B. Two additional bolts (not shown) engage bosses integral with the partition 8 to hold the latter in gas-tight contact with .a recessed flange on the part C. The parts A and B may be made in one piece with a separate valve plate 1 and the two pairs of measuring chambers may be formed by two pairs bolted together with a partition interposed between them instead of by four pairs as shown. When two pairs are used, each is provided with a circumferential recess at about half its depth to receive the periphery of the diaphragm which is held in place by a circular spring. The parts .of the meter casing, the valve plate and some of the moving parts may be die-cast in an aluminium or zinc base alloy, gravity cast in metal .or plastic or moulded in plastic and the valve grids may be formed separately from the valve plate. A prepayment or counting mechanism may be coupled to the meter by a shaft 55 which has a slotted crank in driving engagement with a similar crank on a shaft 53. The latter is driven by reduction gearing immersed in a grease box and driven by the shaft 45. The grease box can be charged with grease, for example by injection, from a position external to the meter case. Specifications 681,133, 681,134, and 681,135 are referred to.