Fluid pressure transducer

A fluid pressure transducer which comprises;

• a body member which contains a porous element having a generally planar distal surface;
• a control fluid inlet means in communication with the porous element;
• a tubular control fluid outlet means passing through the porous element and extending substantially to the distal surface, and having an open end lying in a plane substantially parallel to said distal surface;
• and
• a thin diaphragm having a first face located in close proximity to and essentially parallel to the distal surface of the porous element, the diaphragm being mounted in the body means to serve as a fluid tight barrier between the porous element and control fluid means and a fluid whose pressure is to be measured, the diaphragm normally being in contact so as to close the open end of the fluid outlet means when exposed to ambient fluid pressure, so that a control fluid may be transmitted through the fluid inlet means and porous element to exert a back pressure against the first face of the diaphragm and move the diaphragm out of contact with the open end of the fluid outlet means when the back pressure exceeds the ambient fluid pressure.

A method of limiting diaphragm travel in a null-type, diaphragm actuated pressure transducer in which the diaphragm is exposed on one side to the pressure of the fluid being sensed and on the other side to the pressure of a control fluid which comprises:

• providing a first porous element on the control side of the diaphragm, said element being adapted to uniformly distribute a control pressure over the control side of the diaphragm;
• further providing a second porous element on the sensing side of the diaphragm, said element being adapted to uniformly distribute the pressure of the fluid being sensed over the sensing side of the diaphragm;
• providing sensing means operatively associated with the diaphragm to signal a remote indicator when a null point is reached showing that control pressure and the pressure being sensed are equalized;
• and
• spacing the two porous elements a predetermined distance apart in order to define and limit the maximum displacement of the diaphragm.