GB790531A - Differential pressure responsive devices - Google Patents

Abstract

790,531. Differential pressure gauges. REESE, W. M. March 12, 1956, No. 7621/56. Class 106 (2). A differential pressure gauge comprises a housing 5 divided into two chambers 8, 9 by a centre plate 10 which encloses another chamber 24 with a passage 28 opening directly into a bellows 21 whose outer end 21<SP>1</SP> moves in the chamber 9 and is connected to valves 31, 32 controlling the passage 28, while the chamber 24 is closed out of direct communication with a bellows 18, with outer end 18<SP>1</SP> movable in the chamber 8, but communicates therewith through a single indirect passage 45, 46. The gauge may be used for measuring the drop of pressure through an orifice plate in a gas or liquid flow line, the high and low pressure sides thereof communicating through pipes 3, 4 with the chambers 8, 9. The bellows are filled with a suitable liquid adapted to flow back and forth in response to variations in pressure in the chambers 8, 9 acting against adjustable calibration springs 41. Normal flow is controlled by the valves 31, 32 so that the displacement of the valve shaft 34 gives a measure of the pressure difference. Movement is transmitted from the shaft 34 to indicating or recording apparatus by a disc 53 on the shaft 34 acting on a roller 54 carried by an arm 55 mounted on a pivoted shaft 59. Compensation for variations in the volume of liquid in the bellows 18, 21 due to temperature variation may be provided by linking the shaft 34 to the free end of the arm 55 by a bimetallic strip either straight, U-shaped or multi-looped. A pulsation dampener restriction valve 47, of needle type and manually adjustable, provided in the passage 45, 46 permits normal flow between the bellows, but restricts excessive flow due to sudden surges.