Patent GB-724205-A (GB)
Title: Improvements in or relating to pneumatic gauges
Inventor: BOOSEY FREDERICK ROBERT
IPC: G01B13/00
Filed: 1953-03-09
Abstract: 724,205. Pneumatic gauging- apparatus. SIGMA INSTRUMENT CO., Ltd. March 9, 1953 [March 7, 1952], No. 6021/52. Class 106 (2). [Also in Group XXIX] Pneumatic gauging - apparatus comprises an indicating device having a tube containing liquid communicating at its lower end with one side of a flexible member for limiting displacement of liquid from the tube, a control orifice having air passed therethrough and communicating on its downstream side with the other side of the flexible member (or the upper end of the tube), and means for applying a control pressure to the upper end of the tube (or to the other side of the flexible member) so that when air at constant pressure is fed to the orifice and the jet of a pneumatic measuring head is connected to receive the air passing through the orifice, a variation in the amount of air passing through the jet when the jet is placed close to the object being gauged causes an alteration in the position of the meniscus of the liquid in the tube, the liquid displacement being accommodated by movement of the flexible member. In the embodiment shown a rubber diaphragm 2 divides a circular, flat box 1 into two chambers 3, 4. A pipe 9 passing through the lower chamber 4 is connected by a flexible tube 11 to the lower part of a glass tube 12 and the level of water in these parts is indicated by a black line 14 on a polythene float whose top just touches the meniscus of the water. A source of constant air pressure is connected by a pipe 15 through a pressure regulator 16 to a pipe 17 leading through an orifice 18 and a junction 19 to a measuring head 20. The head 20 may have anvils contacting the object to be gauged with relative displacement of the anvils controlling flow through a jet, it may be a ring gauge with jets round the inner periphery thereof or it may be a plug gauge with jets round its outer periphery. One end of a pipe 22 is connected to the pipe 17 between the orifice 18 and regulator 16 and, between its other end 22B and an orifice 23 therein, a needle valve 24 is adjustable to control the rate of escape of air to the atmosphere. When the measuring head 20 consists of a ring gauge the end 22B is connected to the upper end of the tube 12 and a pipe 10 passing through the upper chamber 3 is connected to the junction 19, when the head 20 consists of a plug gauge the end 22B is connected to the pipe 10 and the junction 19 to the top of tube 12. The capacity of the box 1 can be adjusted by moving discs 5, 8 carried by screws 6 toward or away from each other. Lock nuts 7 are provided and may prevent leakage or a sealing compound may be provided on the threads of the screws 6. The position of the float 13 in the tube 12 is zeroized by manipulating the needle valve 24. When a plurality of dimensions are to be measured simultaneously and compared, several tubes 12 may be arranged close together so that the several floats lie within the normal angle of vision, while their boxes 1 may be disposed in any convenient positions. Specifications 723,793, [Group XXIX], and 724,228 are referred to.