GB1126277A - Improvements in or relating to manometers - Google Patents

Abstract

1,126,277. Pressure gauges. NATIONAL RESEARCH DEVELOPMENT CORP. June 9, 1967 [May 10, 1966], No. 20625/66. Heading G1L. In a manometer comprising a "U"-tube provided with a bend 12 and two vertical sections 10, 11 connected to two water pressure connections connected to two pressure sources 14, 17 to be compared such as static and pitot heads, the arrangement is such that three valves 20, 21 and 24 are open and water is sucked into the U-tube through a connection 22 until the water level in section 11 is slightly above the level of a capillary tube 13. The valves 24, 21 are closed and the water level is lowered by adjusting a plunger 30 until a meniscus in the capillary tube 13 reaches a "zero" position, indicated by a fixed pointer 15, and the valve 20 is then closed. When a pressure reading is to be taken the valve 21 is opened to a second water pressure from source 18 and if this pressure is greater than the pressure from source 14 the water level in a constant level chamber 16 will rise compressing the gas in bend 12 and so displacing the meniscus in tube 13. Second and third plungers 32, 31, which may be coupled by a dowel 34, are then adjusted together or separately to restore the meniscus in capillary tube 13, to the original position opposite pointer 15 and since the volume displaced by the plungers 31, 32 can be correlated with the pressure differences in the U-tube a direct measurement of pressure can be obtained by a reading from a micrometer dial gauge 36 which measures the axial movement of plunger 31.