Fire extinguishers – Special applications – Condition responsive control
Reexamination Certificate
2002-04-15
2004-11-02
Mar, Michael (Department: 3752)
Fire extinguishers
Special applications
Condition responsive control
C169S026000, C169S005000, C137S068270
Reexamination Certificate
active
06810966
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an extinguisher for fighting fire and incipient explosions, the extinguisher including at least one rupture diaphragm, which seals an extinguishing-agent vessel and has a rupture joint.
BACKGROUND INFORMATION
To fight fire and suppress incipient explosions which are caused by flour dust, coal dust, or solvent vapors, one normally uses vessels that are filled with an extinguishing agent (usually extinguishing powder) and are permanently under pressure. In an emergency, these blow the extinguishing agent through a quick-opening valve, into the space where extinguishing is required.
An extinguisher for fighting incipient explosions is described in German Published Patent Application No. 195 44 399, where a tubular extinguishing-agent vessel is sealed on the inside and outside by flat rupture diaphragms. In the interior chamber adjacent to the inner rupture diaphragm, a compressed-gas generator is provided, the generated propellant gas of which ruptures the diaphragms and then expels the extinguishing agent. This extinguisher does not often achieve good results, since the rupture diaphragms seldom burst open in the center, or in an axially symmetric manner. Instead, the diaphragms rupture at a point outside their center, which causes the expelled extinguishing agent to be dispersed in a considerably asymmetric manner. However, it is necessary to expel all of the extinguishing agent in a uniform manner, in order to attain an optimum spray pattern and, thus, success in extinguishing.
In addition, German Published Patent Application No. 42 24 184 describes an extinguisher, where the extinguishing-agent vessel is sealed on the outside by a convex rupture diaphragm, which is provided with circular and radial rupture joints. This diaphragm already opens at a pressure of 0.1 to 1.0 bar above atmospheric pressure. Connected to the extinguishing-agent vessel is a compressed-gas generator, which, in response to being triggered, mixes the extinguishing agent together with the compressed gas and sprays this mixture into the space where the extinguishing is to take place. In order for the extinguishing agent to have a rapid effect, it may be more favorable for the extinguishing agent to only be dispersed after it is expelled from the vessel. The shape of the diaphragm used also does not allow one to compensate for the change in the extinguishing-agent volume as a function of the temperature.
Other conventional extinguishers include rupture diaphragms that are spherically shaped so as to be inwardly concave in the direction of the compressed-gas generator, and are provided with a rupture joint. These rupture diaphragms bulge in response to pressure applied by the gas generator or thermally induced expansion, at some point that, generally, is not at the center of the diaphragms, but rather at an arbitrary position on the spherical diaphragm surface. The bulge extends to the other side in the form of an inversion and results in a rupture joint rupturing off-center. This causes the extinguishing agent to be discharged in a nonuniform manner.
Therefore, it is an object of the present invention to provide a rupture diaphragm for an extinguisher of the type mentioned above, so as to eliminate the above-mentioned disadvantages and cause the rupture diaphragm to burst open in the center, and thus uniformly disperse the extinguishing agent.
SUMMARY
The foregoing object is achieved by providing an extinguisher as described herein. An advantage of the rupture diaphragm according to the present invention is that the planar surface or the depression in the center of the rupture diaphragm allows the diaphragm to be easily inverted in the case of pressure being applied, without local bulging occurring. In this context, the rupture diaphragm behaves like a cup spring. In addition, the rupture diaphragm configured according to the present invention may compensate for thermal expansion of the extinguishing agent, since the planar surface or the depression in the center of the diaphragm is elastic in its movement in the axial direction.
A further advantage results from the circular shape of the planar surface in the center of the rupture diaphragm, in that a uniform load distribution is achieved in response to an applied pressure. This supports a uniform inversion of the diaphragms and prevents them from bulging on the side. The inverting procedure causes the rupture joint provided on the edge of the rupture diaphragm to weaken prior to breaking, so that the actual rupturing event occurs simultaneously on the entire circumference, and the extinguishing agent is expelled in a uniform manner.
An example embodiment of the extinguisher according to the present invention is described in detail below and is illustrated in the drawing in a schematically simplified manner.
REFERENCES:
patent: 2530633 (1950-11-01), Scholz
patent: 3604511 (1971-09-01), Griffith et al.
patent: 3762479 (1973-10-01), Fike et al.
patent: 5031701 (1991-07-01), McLelland et al.
patent: 5291952 (1994-03-01), Arend
patent: 5609210 (1997-03-01), Galbraith et al.
patent: 6178983 (2001-01-01), Culliinane et al.
patent: 42 24 184 (1994-01-01), None
patent: 195 44 399 (1997-06-01), None
patent: 98/39064 (1998-09-01), None
Bauer Karl
Sans Joachim
Schilling Steffen
Bayern-Chemie GmbH
Gorman Darren
Kenyon & Kenyon
Mar Michael
LandOfFree
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