Patent GB-508828-A (GB)
Title: Improvements in and relating to measuring or verifying apparatus
IPC: G01F1/36
Filed: 1938-10-05
Abstract: 508,828. Gauging apparatus. SOC. ANON. DE CONSTRUCTION DE MATERIEL AUTOMOBILE S.A.C.M.A. Oct. 5, 1938, No. 28923. Convention date, Feb. 19. [Class 106 (ii)] Relates to apparatus. of the kind described in Specifications 326,674, [Class 106 (ii)], 341,365, 348,860, and 388,265 in which dimensions are verifed by measuring the pressure in the space between two orifices in series, through which pressure fluid flows, the second orifice having a section which is a function of the dimension to be measured, and consists in providing means to prevent ill-effects when the differences of pressure exceed a predetermined value. In the form shown in Fig. 1, the fluid under pressure is admitted by the conduit 1 and passes through orifices 2, 3 and the chamber 4 separating them, and also through orifices 2<1>, 3<1> and a chamber 4<1>. Between chambers 4, 4<1> is provided a manometer 5, and the pressure indicated represents the difference between orifices 3, 3<1>. To prevent damage due to excess pressure a byepass 6 between chambers 4, 4<1> is provided in which is a spring loaded valve 7 which opens when a predetermined pressure difference occurs. A partition 8 with orifice 9 is provided in one or other of chambers 4, 4<1>. In a modification, the screen 8 with orifice 9 is located in chamber 4<1> as well. In this case a second byepass is provided with the relief valve located in the opposite direction. In a second modification the valve ends of the byepasses are connected up stream of the screens 8. In a device with only the orifices 2, 3, the valve 7 opens the chamber 4 to the atmosphere. Two further forms are shown in which instead of valves, the safety device comprises tubes dipping into chambers containing a liquid forming a seal, the level of the liquid determining the pressure at which the chambers 4, 4<1> are thrown into communi- 'cation. On one of these the liquid chambers are provided with open-ended tubes above which and separate therefrom are fixed caps which prevent liquid being carried over with the gas. In Fig. 7 is shown an apparatus in which several individual measuring devices I, II, III are branched on a single supply conduit 1. Between I and II there are provided manometric columns 12, 121 from the chambers 4, 4<1> and between the columns is a diaphragm 16 dividing a box 17 into compartments communicating respectively with tubes 12, 121 The diaphragm is arranged between two rigid solid or perforated plates 18, 181 adapted to seat on ridges or projections 19, 191 on the box. When one of the discs seats on its ridges the pressure is no longer transmitted in the direction to move it. A byepass 20 connects the tubes 12, 12<1> and is provided with a fine throttle opening 21 which allows equalization during filling. A cock may be provided instead of the orifice. To maintain constant pressure in chamber 4, this communicates by a large conduit 22 with a chamber 23 a wall of which is constituted by a weighted diaphragm. Movements of this are transmitted to an obturator 27 controlling the supply of air. Between II and III the tubes 12, 12<1> connect with chambers 15, 151 the latter being open to the atmosphere. The chamber 15 is connected with a chamber 28 separated from chamber 4<2> by a partition with a throttle 9. Dampening devices 30 formed of a packing of wood or metal chips are provided as shown.