Fire extinguishers – Portable vessels – Gas pressure
Reexamination Certificate
2001-11-29
2004-03-09
Mancene, Gene (Department: 3752)
Fire extinguishers
Portable vessels
Gas pressure
C169S009000
Reexamination Certificate
active
06702033
ABSTRACT:
BACKGROUND
This invention relates to fire suppression, and more particularly to fire extinguishers which may be installed within vehicles.
There are a wide variety of fire extinguishing technologies and fire extinguisher constructions. These include propellant-actuated extinguishers and extinguishers charged with compressed and/or liquified gas.
The basic features of an early propellant-actuated extinguisher are seen in U.S. Pat. No. 2,530,633 (Scholz). Scholz discloses a fire extinguisher wherein “a liquid extinguishing medium, such as methyl bromide, is expelled from its container by gas evolved from the burning of” a pyrotechnic charge. The charge is originally stored in a container which includes electric squibs. The charge container is mounted in an upper end of the vessel within a “container cup”. Opposite the container cup, an outlet from the vessel is formed by an elbow fitting sealed by a rupturable diaphragm. Ignition of the pyrotechnic charge ruptures a wall of the charge container and vents combustion gases into the vessel. The combustion gases serve “as a gas piston acting on the surface of the liquid” rupturing the diaphragm which sealed the outlet and propelling the liquid out of the extinguisher.
The application of a propellant-actuated extinguisher to use in military vehicles is described in U.S. Pat. No. 4,319,640 (Brobeil). Brobeil discloses an extinguisher in many ways similar to Scholz. The exemplary fire suppressant utilized is Halon 1301. The lower end of the extinguisher vessel is sealed by a rupturable diaphragm. A as generating device is mounted atop the neck of the vessel. The exemplary gas generating composition is 62% sodium azide and 38% copper oxide.
U.S. Pat. No. 5,660,236 (Sears et al.) discloses the application of pressure from a gas generator to an annular piston which compresses a fire suppressant located in a central portion of a cylindrical container. This in turn induces the rupture of rupturable disks separating the suppressant from an apertured end portion of the cylindrical container. A portion of the combustion gas bypasses the piston and flows directly to the apertured end portion where it assists in vaporizing the fire suppressant and driving such suppressant from the extinguisher.
U.S. Pat. No. 4,889,189 (Rozniecki) discloses an extinguisher which utilizes a poppet-type “flush valve”. A bladder separates a first chamber containing the suppressant from a second chamber to which the pressurizing gas is admitted. The bladder stretches on pressurization of the second chamber to drive the suppressant from the first chamber. The flush valve (mounted centrally within the bladder) opens once the bladder has reached its maximum stretch (having reduced the space occupied by the first chamber to a small fraction of the total container volume and driven nearly all of the suppressant from the container). The opening of the flush valve allows the propellant gas to be vented from the second volume through the first volume taking with it substantially the remainder of any suppressant.
U.S. Pat. No. 4,579,315 (Kowalski) discloses a pressurized Halon 1301 extinguisher. The extinguisher outlet is normally closed by a poppet valve. The poppet is held in its closed position by a latch which is released by a solenoid and thereby allows the pressure within the cylinder to drive the poppet to an open position.
U.S. Pat. No. 2,557,957 (Ferguson) discloses a manually-actuated, gas-pressurized aircraft fire extinguisher. The pressurant and suppressant are initially held in separate chambers. The two chambers are initially separated by both a membrane or closure and a sliding piston. The closure is ruptured via a manually-actuated piercing device, allowing the pressurant to drive the piston against the suppressant. The piston carries a poppet valve which opens once the piston has reached the end of its travel, allowing the pressurant to drive any residual suppressant from the extinguisher.
U.S. Pat. No. 3,861,474 (De Palma) discloses a dry chemical extinguisher utilizing a compressed gas pressurant. The outlet is normally sealed via mating of a first valve head with a seat. An outer tube circumscribes the seat and depends therefrom extending down and into the body of dry chemical. Concentrically within the outer tube is an inner tube. The lower end of the inner tube is normally sealed by a second valve head. Initially, both the ullage space and the inner tube are pressurized. The valve may be actuated manually or automatically. The automatic actuation is achieved via heating of gas within a bellows. Expansion of the bellows acts to disengage both the first head from its seat and the second head from the lower end of the inner tube. Although gas within the ullage space pushes down on the dry chemical, gas escaping from the inner tube entrains the dry chemical in an upward flow through the annular space between the inner and outer tubes.
U.S. Pat. No. 4,034,813 (Le Day) discloses a gas-pressurized extinguisher closed by a poppet valve having a head upstream and a valve extending downstream. The valve is held in a closed position by a pin having a pivoting end and a free end. The free end of the pin is held by a body of wax or a low melting point alloy. Heat from a fire softens the body, allowing the pressure within the extinguisher to drive the valve into an open position.
U.S. Pat. No. 4,159,744 (Monte et al.) discloses a nitrogen-pressurized extinguisher. The suppressant bottle is sealed by a poppet-type valve wherein the head faces the body of suppressant and the stem is directed outward. The valve opens into the bottle and is activated by either a squib or explosive cartridge acting upon a piston which bears against the stem.
There remains a further need for a high-performance fire extinguisher useful in vehicles and other enclosed spaces.
BRIEF SUMMARY OF THE INVENTION
One aspect of the invention is directed to a fire extinguisher comprising a bottle having an interior and a fire suppressant contained by the bottle when the extinguisher is in a pre-discharge condition. A source of gas pressurizes the suppressant at least when the bottle is in a discharging condition and the suppressant is discharged through an outlet when the extinguisher is in the discharging condition. A valve has a valve element having a closed position sealing the outlet and an open position permitting discharge of the suppressant through the outlet. The valve element is shiftable from the closed position to the open position responsive to a pressure within the bottle exceeding a discharge threshold pressure, whereupon the extinguisher enters the discharging condition and discharges the suppressant through the outlet.
In various implementations, the valve element may comprise a poppet having a head and a stem connected to the head. The head may have a fore surface facing the bottle interior and an opposite aft face from which the stem extends along a poppet axis. The valve may have a locking element which in the pre-discharge condition has a first portion engaged to the poppet and a second portion held relative to the bottle. In the pre-discharge condition the locking element transmits force to the poppet which retains the poppet in the closed position and, responsive to the pressure within the bottle exceeding the discharge threshold pressure the locking element ruptures, whereupon the pressure within the bottle drives the poppet to the open position and the extinguisher enters the discharging condition. A valve return spring may bias the poppet toward the closed position. The return spring is effective to return the poppet from the open position to the closed position when the fire suppressant has been substantially discharged from the extinguisher.
The valve element may comprise a head having a fore face facing the bottle interior and an opposite aft face and a collapsible shaft between the head and a valve body. In the pre-discharge condition, when the pressure within the bottle is lower than the discharge pressure, axial compression of the shaft may be effective to resist rearwar
Arnot Nicholas R.
Callis George J.
Mitchell Robert M.
Aerojet-General Corporation
Bui Thach H
Mancene Gene
Olson Timothy J.
Rosenblatt Gregory S.
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