Liquid Filled Membrane Pressure Gage


In this paper a method of using an axisymmetric, constant volume liquid filled membrane as an underwater pressure gage is described. The membrane material is considered to be neo Hookean and highly extensible. The theory of large elastic deformation is used in the analysis. The hydrostatic pressure variation inside and outside a submerged membrane is taken into consideration. Since the deformed configuration of the membrane is a function of the pressure differential across the membrane, it is possible to use the change of configuration due to various depths of submergence as a measure of pressure differential. However, after complete submergence, configuration changes do not occur, and the pressure differential will remain constant, maintaining a linear relationship between outside and inside pressures. The use of the liquid filled membrane pressure gage is demonstrated by means of a glycerine filled rubber membrane attached to a manometer and submerged to various depths. The governing equations of the membrane configuration which are nonlinear differential integral type are numerically solved. Since the constant volume assumption is violated due to a small amount of liquid flow into the manometer tube, a procedure for the error correction of the manometer reading is provided. An axisymmetric liquid-filled membrane can be conveniently used for the measurement of underwater pressure in shallow or deep depths. For shallow depths the membrane is used to indicate the external liquid level or the pressure caused by it. For depths greater than the inflated size of the membrane a manometer should be attached because, under complete submergence, displacements of the apex do not take place when the membrane volume is constant. A prime advantage of the instrument is that the membrane separates the internal and external liquids, thus increasing the choice among a wide variety of miscible liquids. The liquid-filled membrane also extends the range of pressure measurement as compared to the conventional flexible diaphragm type pressure gages.


Mechanical and Aerospace Engineering

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Article - Journal

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© 1974 Elsevier, All rights reserved.

Publication Date

01 Jan 1974

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