GB295256A - - Google Patents

Abstract

Abstract 295,256. Soc. Anon. Union Technique du Batiment et des Travaux Publics, (Assignees of Langevin, P., and Hocart, R.). Aug. 6, 1927, [Convention date]. Electric - diaphragm pressure gauges; piezoe l e c t r i c pressure gauges.-To measure varying pressure in liquid conduits a piezoelectric crystal subjected to the pressure is employed and connected to a four-electrode valve and measurement is made by an oscillograph. A flanged conduit e has attached to it a casing b with an elastic steel diaphragm d with reduced annular portions d<1>. The crystal a bears against the diaphragm and rests in a groove in a base plate c against which bears screws m<1>, m<2> for adjusting the pressure. The faces of the crystal are connected, the negative to the outer grid f, and the positive to the filament h of a four-electrode valve and the inner 'grid i is made positive and connected to an oscillograph j of which the period (<1>/1500 second) is below the periods concerned. The dimensions of the quartz crystal a and diaphragm d are also chosen greatly to exceed in natural frequency that of the variations in the pressure to be measured. The sensitiveness of the apparatus may be varied by the interposition between the valve and the oscillograph of amplifying means with suitable resistance and batteries, and by shunting the crystal by a variable condenser. A mirror oscillograph may be employed to record the deflections on a drum.

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No inventors recorded.

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