Patent GB-946563-A (GB)
Title: Improvements in or relating to apparatus for metering gases and vapours flowing in pipelines
IPC: G01F15/04
Filed: 1960-03-25
Abstract: 946,563. Fluid-pressure servomotor control systems. H.GEHRE. March 25, 1960 [March 26, 1959], No. 10697/60. Heading G3P. [Also in Division G1] The P/T value of gas being measured by a meter 2 is regulated in a volumetrically-limited section of a pipeline; the section is bounded on one side by the throttle 7 of a P/T senser 3 and on the other side by a pressure regulator 4 and may be constituted by the meter 2 itself. The senser may comprise an elastic vessel, such as a bellows 5, filled with a comparison gas or a computer device which converts the pressure and temperature values into an equivalent setting of the throttle. In Fig. 4, the bellows 5 and valve 7 are fitted in a housing 3<SP>1</SP> at the inlet side of the meter and the bellows is adjustable by a screw 6. A pressure regulator 4 maintains a constant pressure in the outlet pipeline. With decreasing rate of flow, the valve 4 is throttled and the P/T value in the meter is increased but the consequent compression of the bellows tends to close the valve 7 and further increase is prevented. With increasing rate of flow, the bellows expands and increases the flow cross-section at the valve 7. The sensitivity of the regulation can be increased by enlarging the effective volume of the bellows 5 by connecting it to a rigid container 5<SP>1</SP>, as shown in Fig. 5, or by providing links 10, 59, 58 so that the regulator 4 also controls an auxiliary throttle 11 in the valve 7 or in a parallel pipeline 12. The pressure regulator may be a floating valve 39 balanced by its own weight, by a membrane 50, by a weighted lever 47 and by the pressures on both its surfaces. The valve 39 controls the throttle 11 or 11<SP>1</SP> by a linkage 53 of which the leverage is increased for increasing pressure by means of a membrane 60. The bellows 5 may be connected to the valve 7 by a servo system and, as shown in Fig. 3, the servo system may also control a variable transmission drive 33 for correcting the meter registering mechanism 34. A jet tube 13 is pivoted in the housing 3 and is connected by a pipe 20 to the inlet pipeline. A nozzle 14 at one end of the tube 13 normally lies between two apertures 15,16 in a cylinder 18 having a membrane 19<SP>1</SP> or piston connected to the valve 7. According to the movement of the bellows 5, the nozzle 14 approaches either the opening 15 or 16 and the valve 7 is set accordingly. The nozzle 22 at the other end of the jet tube 13 co-operates with a movable plate 23 which has openings 24, 25 and is connected to a membrane 27. Movement of the nozzle directs the flow through either the opening 24 or 25 to the bottom or top of the membrane and the plate 23 moves until the flow impacts both openings equally and then comes to rest. Links 22, 24 connect the plate to the variable transmission drive 33. The nozzle 14 and 22 can be on separate jet tubes, each operated by a separate elastic vessel. Where the jet tube 13 has a single nozzle for controlling only the valve 7, the pivot point may be formed as a cock to shut off the flow through the pipe 20 when the valve 7 is moved to the closed position. In Fig. 5, a spring-loaded membrane 72 is subject to the inlet pressure through a pipe 52 and is connected to a shaft 68 having a ball tip 69 within a fork 67 on which the pressure regulator 4 acts. With a small pressure drop across the membrane, the bellows 5 closes the valve 7 and the spring 73 of the membrane moves the ball 69 so that it is over the pivot point 66 of the fork end, the movement of the draft 68 being limited by an abutment 83; the pressure regulator 4 and the valve 7 cannot then react on each other. With a greater pressure drop, the membrane 72 moves the shaft 68 to the left and the decreased back pressure on the regulator 4 causes it to lift the fork 67 and add to the opening movement of the valve 7 caused by the bellows 5. The bellows 5 may be fitted at the outlet side of the meter and be connected by mechanical, hydraulic or other means to a valve 7 at the inlet side or the bellows 5 and valve 7 may both be fitted at the outlet side and the pressure regulator, consisting of a floating valve balanced by a membrane and weight, be fitted at the inlet side.