GB790294A - Differential fluid pressure controlled apparatus - Google Patents

Abstract

790,294. Pressure gauges. FOXBORO CO. Aug. 26, 1955 [Sept. 1, 1954], No. 24650/55. Class 106 (2). [Also in Group XXIX] A pneumatic pressure transmitter controlled in response to a differential fluid pressure includes a sealed casing 10, Fig. 2, having a resilient diaphragm 74 forming part of the wall thereof, a force bar 72 extending through and secured to the diaphragm, differential pressure responsive means, e.g. the corrugated diaphragm 40 across which the pressure differential across a fluid flow orifice is applied via ports 46, 52, connected at 86 to the force bar to turn it about an axis approximately in the plane of the resilient diaphragm and a flexible linkage system 108, 116 secured to the casing and to the force bar outside the casing to inhibit axial movement of the force bar. An upright member 78 carries at 212 a flapper 104 controlling a nozzle 152 leading from a pneumatic relay 157 containing a supply and waste valve. The flexible linkage comprises two pairs of leaf springs 108, 116 secured at their lower ends to the base 76 of the member 78, the pair 108 straddling and secured at the top on the axis of the rod 72, and the pair 116 straddling the flapper, the pairs being connected by a bar 124 adjustable at 136. A block 120 carried by the spring 116 has a bar 148 embracing the flapper. Output pressure at 30 leads from the relay 157 to an indicating or controlling device and, to provide a follow-up device, is also led via 160 to a bellows 162 acting on a lever 176 adjustably pivoted at 186 on the member 78, connected at its upper end to the block 120 and adjustably loaded by a spring 182 at its lower end. Specifications 670,427, [Group XXIX], and 672,879 are referred to.