Abstract: A radically simple, reliable, inherently accurate, intrinsically wide-pressure-range adaptable, low to ultra-high pressure capable capacitive transducer is made from a reference capacitor and a variable capacitor, one electrode of each of which is formed of a flat conductive layer on a circular insulating plate. The reference capacitor electrode is a peripheral annulus surrounding the central disk constituting the variable capacitor electrode. The insulating plate is rigidly held slightly spaced apart from a flat, flexible metal diaphragm which provides the opposing electrode for each capacitor. The diaphragm is an integral part of a pressure fitting which includes a fluid pressure input coupling and a pressure chamber adjacent to the diaphragm.

Abstract: A corrosion proof differential pressure transducer includes a central disk and two thin diaphragms mounted close to but spaced from the disk on both sides thereof, with the diaphragms being intercoupled to move together. This may be accomplished, for example, by a rod passing through a hole in the center of the central disk which is secured to each of the diaphragms; or by a fluid such as silicone oil in the space between the diaphragms and flowing through one or more holes through the central disk. At least one of the diaphragms, the central disk and the rod (when one is used) are formed of alumina, quartz, or other inert, insulating material having substantially zero mechanical hysteresis. One of the diaphragms may be a thin, tough, flexible insulating membrane. Conductive plates providing variable capacitance with changes in pressure may be mounted on the inner surface one or both of the diaphragms and on the facing surface of the central disk.

Abstract: A corrosion proof differential pressure transducer includes a central disk and two thin ceramic diaphragms mounted close to but spaced from the disk on both sides thereof, with the diaphragms being intercoupled to move together. This may be accomplished, for example, by a rod passing through a hole in the center of the central disk which is secured to each of the diaphragms; or by a fluid such as silicone oil between the diaphragms and flowing through one or more holes through the central disk. The diaphragm, and disks and the rod are formed of alumina, quartz, or other inert, insulating material having substantially zero mechanical hysteresis. Conductive plates providing variable capacitance with changes in pressure are mounted on the inner surface one or both of the diaphragms and on the facing surface of the central disk. A housing and associated gaskets direct pressures from two different fluids to the two diaphragms, so that the differential pressure is measured.

Abstract: A capacitive pressure transducer comprising a pair of disc shaped members having planar surfaces made from an insulator material, one of the members being several times thinner than the other plate and flexible and constituting a diaphragm and the other thicker plate constituting a stationary plate. A thin conductive film is formed on the surface of each of the members to form the plates of the capacitor. A glass frit is applied on the marginal edge of each member and when the members are held in adjacent relationship, the assembly is fired to seal the two members together while spacing them a predetermined distance apart so that the two conductive plates are opposite each other and are separated by an open gap of a predetermined distance, the two conductive plates being insulated one from the other. Leads are electrically connected to the conductive plate of each disc through the fused glass frit.

Abstract: A capacitive pressure transducer comprising a pair of disc shaped members having planar surfaces made from an insulator material, one of the members being several times thinner than the other plate and flexible and constituting a diaphragm and the other thicker plate constituting a stationary plate. A thin conductive film is formed on the surface of each of the members to form the plates of the capacitor. A glass frit is applied on the marginal edge of each member and when the members are held in adjacent relationship, the assembly is fired to seal the two members together while spacing them a predetermined distance apart so that the two conductive plates are opposite each other and are separated by an open gap of a predetermined distance, the two conductive plates being insulated one from the other. Leads are electrically connected to the conductive plate of each disc through the fused glass frit.

Abstract: Two square plates of ordinary inexpensive soda lime glass are spaced apart from one another, and are sealed together by a ring of glass frit, with the two plates overlying one another, but with the corners of the two plates displaced so that the corners of each of the two plates extend past the sides of the other plates. The plates may be spaced apart by a small distance, for example, from about 1/2 to several thousandths of an inch, and thin conductive layers on the two facing surfaces form a variable capacitor which changes in capacitance when pressure is applied to the outside of the two plates. Connections for the conductive plates extend out to the corners of the plates beyond the sides of the other plate to permit easy access. Electrical connections are made through the use of elongated conductive rubber elements.

Abstract: A capacitive pressure transducer comprising a pair of thin discs made from an insulator, a thin metal film metalized onto each of the discs and forming the plates of the capacitor, and means for bonding the two discs together such that the two metal films are opposite each other, the two metal films are separated by an open gap, and the two metal films are insulated one from the other. When pressure is applied to the discs, the discs are displaced thereby changing the capacitance of the pressure transducer.