Non-symmetrical overload protection device for differential pressure transmitter

Abstract

A differential pressure to electrical signal transmitter has a pair of barrier diaphragms and a central control diaphragm located between the barrier diaphragms. Input fluids are applied to respective chambers on the outside of the barrier diaphragms while the chambers between the control diaphragm and the barrier diaphragm are filled by corresponding substantially incompressible fill liquids. The fluid pressure of the two fill fluids are conducted by corresponding fluid channels to respective sides of a displacement sensing element to produce an electrical signal representative of differential pressure. The control diaphragm is biased by spring loaded spacers located on corresponding sides of the control diaphragm. The spacers have fluid passages to permit the respective fill fluids to reach the control diaphragm. A first spacer is concentric with a first chamber on a first side of the control diaphragm while a second spacer is concentric with a second chamber having a smaller diameter than the first chamber and being located on the other side of the control diaphragm. Consequently, the second spacer overlies the peripheral edge of the first chamber to produce a differential input fluid pressure overload response correlated to a non-symmetrical ratio of the directional strength of the displacement sensing element.

Dependencies are inferred from the claim text.