Temperature compensated pressure differential sensing devices, including improved press-to-test and glass header switch mounting

A pressure differential sensing device comprising:

• A. a base comprising a bottom plate and a mounting shank depending from said bottom plate, said mounting shank and said bottom plate having a bore formed therethrough, and said bottom plate having a cylindrical portion with threads formed thereon;
• B. a cup-shaped cap having threads formed on the side walls thereof, said cup-shaped cap threadably mounted to the threaded cylindrical portion of the bottom plate of said base, and means for sealing said cup-shaped cap to said base, whereby said base and cup-shaped cap together comprise a housing defining a sealed cavity communicating with the exterior of said housing through the bore;
• C. a flexible gas-filled sealed capsule mounted on one of the base or cup-shaped cap;
• D. a mechanically operated switch having an actuating member, said switch mounted on the other of the base or cup-shaped cap with the actuating member oriented toward the capsule, whereby the position of the capsule relative to the actuating member of the switch is adjustable by rotating the cup-shaped cap relative to the base;
• and
• E. signal means operated by said switch,
• wherein the device is attached to a pressurized chamber by means of the shank and adjusted such that a signal is produced at low pressurization of the pressurized chamber and no signal is produced at normal pressurization of the pressurized chamber, whereby a loss of gas from the chamber results in a decrease of the gas pressure of the chamber relative to the internal gas pressure of the capsule thereby permitting the capsule to expand, the expansion of the capsule operating the switch and providing a signal indicating the decrease in pressure.

A pressure differential sensing device comprising:

• A. a mechanically operated switch including an actuating member and at least one metal switch terminal;
• B. a glass header comprising a glass plate, a metal edge member hermetically sealed to the periphery thereof, and a plurality of metal eyelets corresponding to the number of switch terminals of said switch, each metal eyelet hermetically sealed to an opening in said glass plate, wherein each of said at least one metal switch terminals is positioned in a corresponding one of said eyelets and soldered thereto to mount said switch to said glass header;
• C. a metal housing defining a cavity, an inlet bore to said cavity and a mounting shank at least partially defining said inlet bore for connecting said inlet bore to a pressurized chamber, said housing further defining an opening, wherein said glass header with said switch mounted thereto is secured to said housing by soldering said metal edge member to said housing about said opening with said switch actuating member disposed within said cavity, thereby sealing said cavity except for said inlet bore;
• D. a flexible gas-filled sealed capsule mounted to said housing in said cavity adjacent to the switch actuating member;
• and
• E. signal means operated by said switch;
• wherein the device is attached to pressurized chamber with the inlet bore in communication therewith, whereby the gas pressure of said chamber acts on the exterior of said capsule, whereby a loss of gas from the chamber results in a decrease of the gas pressure in the chamber relative to the internal gas pressure of the capsule, thereby permitting the capsule to expand, the expansion of the capsule operating the switch and providing a signal indicating the decrease in pressure.

A pressure differential sensing device comprising:

• A. a base having
• 1. a bottom plate,
• 2. a cylindrical side wall upstanding therefrom, said side wall having threads formed thereon,
• 3. a mounting shank depending from the bottom plate, said mounting shank and bottom plate having a bore formed therethrough;
• B. a flexible gas-filled sealed capsule comprising two convoluted diaphragms joined together along their peripheral edges, said capsule mounted on said bottom plate;
• C. a generally cylindrical housing cap having threads formed thereon, said housing cap threadably mounted to the cylindrical side wall of said base, said side wall and said housing cap surrounding said capsule, and sealing means sealing said side wall and said housing wall, said housing cap defining an opening;
• D. a glass header closing the opening defined by said cylindrical housing cap, said glass header comprising a glass plate, a metal edge member hermetically sealed to the periphery of said glass plate, and at least one metal eyelet mounted through said glass plate and hermetically sealed thereto, said glass header secured to said housing cap by soldering the metal edge member thereto about said opening, whereby said base, housing cap and glass header together define a chamber enclosing said capsule and whereby said bore provides communication into said chamber.
• E. a mechanically operated switch including an actuating member and at least one metal switch terminal, said terminal extending through and soldered to said metal eyelet of said glass header to mount said switch to said glass header, said switch oriented with said actuating member disposed toward said capsule, whereby the position of said actuating member relative to said capsule is adjusted by rotating said housing cap relative to said base on the threads mounting said housing cap to said base;
• and
• F. signal means operated by said switch,
• wherein the device is attached to a pressurized chamber by means of the shank and adjusted such that a signal is produced at low pressurization of the pressurized chamber and no signal is produced at normal pressurization of the pressurized chamber, whereby a loss of gas from the chamber results in a decrease of the gas pressure of the chamber relative to the internal gas pressure of the capsule thereby pemitting the capsule to expand, the expansion of the capsule operating the switch and providing a signal indicating the decrease in pressure.