Fire extinguishers – Automatic receptacles – Explosive
Reexamination Certificate
2003-01-03
2004-05-11
Mancene, Gene (Department: 3752)
Fire extinguishers
Automatic receptacles
Explosive
C169S026000, C169S066000, C169S068000, C137S068230
Reexamination Certificate
active
06732809
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an apparatus for distributing granular material.
The invention relates more particularly to an apparatus for delivering a granular explosion suppressant to the site of an explosion, an incipient explosion, or a deflagration.
There are many types of granular materials, used for many applications. In some applications, it is desirable to distribute the material in a particular pattern. The distribution pattern is sometimes referred to as the “spread” of the granular material.
For example, some types of explosion suppressing systems operate by blowing granular suppressants into a location that is to be protected from explosion. Explosion suppressing systems are widely used in applications where potentially explosive substances such as dusts or vapors are present, especially when those explosive substances are sealed or otherwise enclosed within a limited volume. Examples of locations that might be protected include, but are not limited to, granaries, flour mills, food and pharmaceutical processing machines, petrochemical distillation equipment, solvent baths, etc.
In explosion suppressing systems it is often advantageous to produce a broad, relatively even distribution of suppressant material, without the necessity of moving the distribution device. Such a device is described herein as an exemplary embodiment according to the principles of the claimed invention.
However, it is noted that the claimed invention is not limited only to explosion suppression systems. Devices and methods according to the principles of the claimed invention may be suitable for a variety of other applications, as well. For example, when loading grain into silos or bins it is often advantageous to produce a broad and even spread of grain, rather than to produce a pile directly beneath the loading point.
With regard to terminology, it is noted that in the art of explosion suppression, the term “explosion” is commonly used to refer particularly to the rupture of a vessel or other enclosure. Even if flames are present within a vessel, this is not considered an explosion unless the vessel fails physically, i.e. is breached, shattered, melted, etc. Cases where flames are present but the vessel has not exploded are commonly referred to as “deflagrations”, or alternatively as “incipient explosions”. Explosion suppression typically focuses on extinguishing a deflagration before a vessel or enclosure actually explodes.
In addition, although the term “granular” is sometimes used to refer to materials that are particularly coarse, it is not used in this narrow sense herein. With respect to the claimed invention, “granular material” includes any flowable material composed of individual solid bodies. Thus, it includes extremely fine material such as flour and other powders, extremely coarse material such as large gravel, and material of intermediate coarseness such as sugar.
With regard to the exemplary case of explosion suppressing systems, at least three major types are known. None are entirely satisfactory.
So-called fixed spreader systems comprise a spreader assembly that extends into the volume that is to be protected. An example of a fixed spreader system
10
is shown in FIG.
1
. As may be seen therein, a pressurizer
12
is connected to a reservoir
14
for suppressant. The pressurizer
12
and reservoir
14
are connected to a flange
16
that is mounted to the wall
18
of the vessel that is to be protected. A spreader head
20
extends past the wall
18
, and into the interior of the vessel.
When activated, the pressurizer
12
puts pressure on the suppressant in the reservoir
14
, and forces it through the spreader head
20
. The suppressant spreads out from the spreader head
20
into the vessel, and extinguishes the deflagration, thus preventing the explosion.
Fixed spreader systems suffer from a number of disadvantages.
First, the spreader head
20
protrudes into the protected volume. Many volumes that are or might advantageously be protected from explosions include working machinery, such as grinders or mixers. If a fixed spreader system is to be used for such applications, the machinery must be designed so as to avoid the spreader head, or there is a risk of damage to either the machinery or the head itself.
Second, the open structure of the spreader head
20
protruding into the vessel provides many places where contaminants and/or bacteria may accumulate. This is a particular drawback for applications that require a high degree of hygiene, such as food and pharmaceutical processes.
Even if the spreader head
20
is somehow covered, as by a spreader cap
22
, the need to arrange machines to avoid it leaves a “dead zone” surrounding the spreader head
20
. Contaminants and bacteria can build up in this area as well.
Another known explosion suppressing system is the so-called flush system, illustrated in FIG.
2
. Like a fixed spreader system
10
, a flush spreader system
30
comprises a pressurizer
32
connected to a reservoir
34
. The pressurizer
32
and reservoir
34
are connected to a spreader assembly
36
that is mounted to the wall
38
of the vessel that is to be protected.
The spreader assembly
36
does not penetrate the vessel wall
38
, and thus it avoids some of the disadvantages of the spreader head
20
.
However, conventional flush spreader assemblies
36
are extremely complex, requiring many parts, some of which move during operation. As a result, they are very difficult and expensive to build and install.
Furthermore, after an explosion suppressing system activates, it must be serviced. This includes such tasks as recharging the pressurizer, adding more suppressant, etc. It is also necessary to clean the system, and replace any parts that were damaged or worn when the system activated. Since conventional explosion suppressing systems operate at pressures of up to 900 psi or more, damage is not uncommon, and certain parts are considered disposable.
Because the flush spreader assembly
36
is so complicated, even servicing and even routine maintenance can be time-consuming and complex.
In addition, the highly complex mechanisms in the spreader assembly
36
provide opportunities for the accumulation of contaminants and the growth of bacteria.
A third known explosion suppressing system is the telescopic system, shown in FIG.
3
.
As with other conventional systems, a telescopic spreader system
50
includes a pressurizer and a reservoir (not shown in FIG.
3
). The pressurizer and reservoir are connected to a spreader assembly
52
. The spreader assembly
52
is mounted at least proximate to, and sometimes in contact with, a flange
54
that is mounted to the wall
56
of the vessel that is to be protected. The flange defines an aperture
58
therethrough.
The aperture
58
is covered by a burst seal
60
, which is held in place by a clamp ring
62
and sealed with a gasket
64
.
The spreader assembly
52
includes a spreader head
66
disposed inside of a housing
68
. The spreader head
66
is movable with respect to the housing
68
. When activated, the spreader head
66
is propelled forward (to the left, as illustrated) and partially out of the housing
68
. The spreader head
66
punches through the burst seal
60
, extending past the vessel wall
56
and into the protected vessel. Suppressant flows through the spreader head
66
, extinguishing or preventing explosions.
A shock ring
70
around the spreader head
66
helps to absorb the impact of the spreader head
66
, and also seals the spreader head
66
against the housing
68
.
The telescopic spreader system
50
also avoids some of the disadvantages of the fixed spreader system
10
. While not in use, it does not extend into the volume it protects. However, in the event of an explosion or an impending explosion, the spreader head
66
enters the vessel at high speed. Thus, there is the potential for damage to machinery inside the vessel and/or the spreader head
66
. Alternatively, there is a loss of capacity and the potential for the build-up of contaminants and b
Bouchard Peter Paul
Karadizian Richard Zaven
Gorman Darren
Kidde-Fenwal
Mancene Gene
Merchant & Gould P.C.
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