Patent GB-742648-A (GB)
Title: Improvements in or relating to volume reduction or correction devices for measuring gases flowing in pipe-lines
IPC: G01F15/04
Filed: 1952-08-11
Abstract: 742,648. Integrating-apparatus. GEHRE, H. Aug. 11, 1952 [Sept. 8, 1951], No. 20216/52. Class 106 (4). Integrating mechanism in a meter for measuring the volume of a gas flow actuates correcting means in a counting mechanism drive, being influenced by the differences between the service overpressure of the gas to be measured and a second pressure depending only on the barometric state and comprises a pressure balance 12, 13 carrying on its pendulum arm 21 a control member 23 with a curved rimmed aperture for the engagement of a feeler member 26 periodically actuated by the meter, the curves of the aperture being empirically determined to introduce the required correction. The invention may be applied to reducing the volume V of a gas flow at temperature T and pressure p to its volume Vo at standard conditions of temperature To and pressure po by integrating Vo given by Vo=ZV, where Z = 1+pu-pu*/po (1-R)-R, where R =T-T 0 /T , pu is the service overpressure of the gas, i.e. p u =p - ba where ba is the atmospheric pressure and pu*=p 0  - ba is the overpressure of an auxiliary gas enclosed with temperature controlled volume so that its pressure remains constant. Apparatus for integrating Vo comprises a vessel 1 enclosing a gas and having a wall 2 movable by means of a lever 4 pivoted at 3 and positioned by a thermometer 7 influenced by the temperature of the gas in the vessel 1 through a temperature sensitive element 8 so as to vary the volume of the gas and keep its pressure constant at po. This pressure acts through a diaphragm 14, upon one of two knife-edges 12, 13 equally spaced about the pivot knife-edge 11 of a balance arm and the service pressure of the gas acts on an identical diaphragm 15 bearing on the other knife-edge 13 so that the difference pu - pu* of the two over-pressures causes a displacement of the balance arm which is transmitted through a steel band 18 to the drum 20 of an inclination balance mounted on knifeedges 19. The displacement is transmitted to the pendulum arm 21 with a weight 22 carrying a frame 23 having two inner curved surfaces, the system being balanced by a counterweight 25, and the position of the frame 23 determines the limits of the movement of the feeler arm 26, 28 which is oscillated by a spring 29, connecting rod 30 and crank pin 31 eccentric on a gearwheel 32 driven through a clutch 34 by the meter shaft 33. A counter 51 is driven through adjustment mechanism 50 by the planet-wheel 38 of differential mechanism which transmits the sum of the movements of two sun-wheels 37, 39 driven respectively by the gear-wheel 32 through gear-wheel 36 and through the oscillating arm 28 by means of linkwork 42, 43, pawl and ratchet 44, 45 and gear-wheels 48, 49. The frame 23 is displaced in proportion to the difference pu - pu* and its curved surfaces are shaped, the upper arcuately with centre at the knife edge 19 and the lower empirically so that each stroke of the arm 28 and thence the rotation of the wheel 39 depends on pu-pu*/p 0  and the various gear ratios are so chosen that the rotation of the wheel 37 is one so that the rotation of the wheel 38 is proportional to 1 + pu-pu*/p 0  which is the value of the correction factor Z when T=To, i.e. when R=O. For other values of T and R the rotation of the wheel 39 is further modified through a control device 53, Fig. 2, sensitive to the service temperature of the gas, which, through linkwork, moves the pivoted arm 28 in a direction perpendicular to the plane of the frame 23 so that its oscillatory movement is limited by another frame having its lower curved surface shaped so as to modify the stroke of the arm 28 to be proportional to pu-pu*/p 0  (1 - R) for the value of R appropriate to the temperature while the radius of the upper curved surface is chosen so as to subtract R from each stroke and so make the rotation of the wheel 38 proportional to Z. A number of frames appropriate to different temperature ranges are mounted adjacent one another and the steps from surface to surface so formed are ground down to form continuous surfaces so that the modifications required by varying temperature are made continuously.