Pressure change responsive alarm apparatus

Claim 2

An alarm system for determining through pressure differentials that a door leading to an enclosed environment has been opened or closed, said environment normally maintained at a pre-determined pressure, said alarm system comprising a rate of pressure change detecting means located in said enclosed environment and adapted to sense said pressure change, said rate of change pressure detecting means comprising a dynamic chamber coupled to said enclosed environment, a static chamber isolated from said enclosed environment, fluid passage means connecting said dynamic chamber to said static chamber, said fluid passage means controlling the rate of flow between the chambers as a function of the pressure differential between said chambers, elaStic diaphragm means separating said static and dynamic chambers, variable inductive means for sensing movement of said diaphragm and varying a frequency in response to said movement, discriminator means connected to said rate of pressure change detecting means to provide an output signal responsive to said pressure changes, and alarm means responsive to said output signal to activate a discernible alarm display device responsive to the movement of said door.

Claim 3

The alarm system of claim 1 wherein said discernible alarm display device is an audible buzzer.

Claim 4

The alarm system of claim 1 wherein said discernible alarm display device is a visible light.

Claim 5

An alarm system for determining through pressure differentials that the integrity of an environment has been violated, said environment normally maintained at a pre-determined pressure, access means in said environment, said access means including closure means movable from an open position to a closed position, and sensing the pressure of said environment when said closure means moves from its closed position to its open position, said alarm system comprising rate of pressure change detecting means located in said environment adapted to sense said pressure change, alarm means associated with said rate of pressure change detecting means for creating a signal responsive to said pressure sensed, said rate of pressure change detecting means comprising a region maintained at the pressure of said environment, a static chamber, diaphragm means separating said region and said static chamber, fluid passage means interconnecting said static chamber and said region, said fluid passage means affecting a flow between said chamber and said region that is substantially proportional to the pressure difference between the pressure in the static chamber and the pressure in the region, a pair of inductive means located on opposite adjacent sides of the diaphragm with one inductive means in the region and the other inductive means in the chamber, mechanically permeable material secured to the opposite side of the diaphragm for varying the inductance of said pair of inductance means as the diaphragm moves, the variation in the inductance for varying the frequency at the output of said inductances, said means associated with said rate of pressure change detecting means comprising discriminator means to transform the change of frequency to a change in amplitude, and means responsive to the change of amplitude for operating said alarm means.

Claim 6

An alarm system for determining through pressure differentials that the integrity of an environment has been violated, said environment normally maintained at a pre-determined pressure, access means in said environment, said access means including closure means movable from an open position to a closed position, and sensing the pressure of said environment when said closure means moves from its closed position to its open position, said alarm system comprising rate of pressure change detecting means located in said environment adapted to sense said pressure change, alarm means associated with said rate of pressure change detecting means for creating a signal responsive to said pressure sensed, said rate of pressure change detecting means comprising a region maintained at the pressure of said environment, a static chamber, diaphragm means separating said region and said static chamber, fluid passage means interconnecting said static chamber and said region, said fluid passage means affecting a flow between said chamber and said region that is substantially proportional to the pressure difference between the pressure in the static chamber and the pressure in the region, a pair of inductive means located on opposite adjacent sides of the diaphragm with one inductive means in the region and the other inductive means in the chamber, mechanically permeable material secured to the opposite side of the diaphragm for varying the inductance of said pair of inductance means as the diaphragm moves, the variation in the inductance for varying the frequency at the output of said inductances, said means associated with said rate of pressure change detecting means comprising discriminator means to transform the change of frequency to a change in amplitude, and means responsive to the change of amplitude for operating said alarm means.