Note: Descriptions are shown in the official language in which they were submitted.
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SPRINKLER SYSTEM AND SPRINKLER ASSEMBLY THEREFOR
This invention relates to a sprinkler system and,
more particularly to a sprinkler assembly of a sprinkler
system for use with corrosive environ~ents.
ACKGROUND OF THE INVENTION
In many systems for the suppression of fires, one or more
sprinkler heads are connected to a piping system that, upon
activation in response to raised temperatures, will emit
fire extinguishing fluid. The sprinkler heads usually
include a fusible or frangible element such as a plug,
strut, gasket or ring to maintain the sprinkler head closed
when inactive. Depending on the application and the
envlronment, the Eusible material is adapted to fuse at a
; predètermined temperature that can range from 50C to
several hundred degrees Celcius.
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The prior art is replete with references to sprinkler heads
containing a fusible or ~ frang1ble element. More
specifically, a number of references disclose fusible plugs
or sprinkler heads equlpped with such plugs. In US 1 736
256;and 1 898 482 are disclosed sprinkler heads that have
a passage with grooves filled with a fusible material (wax,
stearine or other organic compound) separated from the
con~tlnuation of the pa~ssage through an outside-threaded
portion of the head by a frangible diaphragm. In U.S. 1
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925 007 a fusible plug is disclosed made of fusible alloy
or solder. The fusible unit comprises a load-sustaining
element and a protective envelope of a non- metallic
fusible material. In U.S. 2 431 llO i5 disclosed a fusible
core in the bore of a non-fusible, elongated, screw-
threaded plug for boilers. In U.S. 3 ~39 103 is ~isclosed
a fusible plug for a refrigeration system comprising a
fusible alloy (melting point range 70-190C), and a
securing rivet inserted in the plug body to seal the
opening. U.S. 3 605 902 and 3 638 734 relate to the use of
a fusible alloy element having a plated coating, jacket or
: stretchable sleeve to prevent cold flow, the alloy being a
: Pb-Sn-Bi-Cd alloy melting at 74C. U.S. 3 771 605 and 3
810 511 disclose sprinkler heads with a threaded nozzle
aperture sealed with a fusible material for a fire
extinguishing system that is charged with air and connected
. to a water supply system so that the sprinkler heads remain
:~ dry until the system is activated.
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:: ~ Most of these references disclose, in addition to the
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: 20 fusible elemPnt, means to retain the element in the plug on
; the sprinkler head, such as a frangible diaphragm, a
: : protecting envelope, a sealing fllm, a rivet or reinforcinq
: :: : means. In some uses, the fusible element is not directly
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or has a limited area exposed to the atmosph~re, while upon
act~ivation the retaining means may not provide free passage
for the fluid. None o the sprinkler heads according to
the prior art is useful in hlghly-corrosive environments,
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especially in those in which highly-corrosive gases are
contained in ducts or pipes made of material such as
fibreglass-reinforced plastic. Most prior art sprinkler
heads have parts that would be prominently exposed to the
corrosive substances.
SUMMARY OF THE INVENTION
We have now developed a sprinkler assembly as part of a
fire suppression system for use with ducts carrying flows
of highly-corrosive gases. The gases may contain
particulates. The ducts have a multiplicity of integral
spaced~apart nozzles each with an inserted adapter provided
with a sprinkler head. Only the face oF each adapter and
the tip of the sprinkler head are exposed to the corrosive
gases. The sprinkler head, which has a central fluid
passage and a fusible fill, is threaded into one end of a
central fluid passage in the adapter, which has an adapter
flange at its opposite end. The adapter flange is clamped
between a 1ange on the nozzle and a pipe flange with a
central opening adapted for connection to a source of
extinguishing fluid. The opening in the pipe flange forms
a continuous passage for fluid with the central fluid
passage in the adapter and the fluid passage in the
sprinkler head. The sprinkler head consists of a
corrosion-resistant body with an outside threaded portion
adapted for screwing into the threaded end of the fluid
passage in the adapter, a seal plug in the threaded
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portion, a low-melting bismuth-lead alloy fill secured in
the opposite end, and a piston between the plug and the
fusible fill. The small protruding section of the body and
the fill in the sprinkler head provide full yet limited
S exposure to the flow of corrosive gases in the duct. Upon
activation, the fusible fill melts, ,and fluid pressure
ejects both plug and piston rapidly and completely from the
sprinkler head, thereby providing full bore for the passage
- of fluid. The piston in the sprinkler head and the mass
and material of the adapter protect the fusible fill from
any cooling effect.
It is, therefore, an object of the present invention to
provide a fire suppression system for ducts carrying flows
of corrosive gases. It is another object to provide a
sprinkler assembly for use with the system. It is still
another object to provide a sprinkler head that has only a
small part exposed to corrosive substances. It is a
further object to provide a sprinkler head for use in a
fire suppression system for ducts carrying flows of
corrosive gases that has a short response time and wherein
a fusible plug is protected from any cooling effect.
Accordingly, there is provided in a first embodiment a fire
~-~ suppression system for ducts carrying flows of corrosive
gases, said system comprising at least one fluid pipe for
2s conducting extinguishing fluid, said ducts each having a
wall with an inner wall surface and a multiplicity oE
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noæzles mounted perpendicular to said wall with one end in
said wall and spaced along the length of said ducts, said
nozzles each having an nozzle flange at the other end; an
adapter slideably inserted in each of said nozzles, said
adapter having an adapter face at one end, an integral
adapter flange at the opposite end and a central adapter
passage having a threaded portion in proximity to said
adapter face, said adapter face being substantially flush
with said inner wall surface of said duct~; a pipe flange
with a central opening connected to said fluid pipe; said
integral adapter flange being rigidly clamped between said
nozzle flange and said pipe flange; a sprinkler head
screwed into said threaded portion of said central adapter
passage such that a portion of said sprinkler head
protrudes from said passage, the protruding portion being
exposed to said flows of corrosive gases, said sprinkler
head having a central sprinkler head passage containing a
: seal plug at one end, a fusible fill at the opposite end at
said protruding portion and a piston between said seal plug
:~ 20 and said fusible fill; said fluid pipe, said central
adapter passage and said central sprinkler head passage
forming a continuous clean passage for conducting
; extinguishing fluid when upon actlvation of said system by
melting of said fusible fill, fluid pressure cleanly ejects
said piston and said seal plug from said central sprinkler
head passage; and said adapter and said piston forming an
: effective barrier against heat transfer and preventing any
cooling effect to reach said fusible fill.
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~ccording to a second embodiment, there is provided a
sprinkler assembly for a fire suppression system and for
use with corrosive gases flowing in a duct having a wall
with an inner surface, said sprinkler assembly comprising
an adapter having an adapter face at qne end, an integral
adapter flange at the opposite end and a central adapter
passage; said adapter being slideably inserted in a nozzle
integral with said duct and mounted perpendicularly to said
wall with one end in the wall of said duct and having an
integral nozzle flange at the other end, such that said
adapter face is substantially flush with said inner wall
surface of the duct: said central adapter passage in the
.~ adapter having a smaller diameter section in proximity to
said adapter face, said smaller diameter section having a
threaded portion adjacent said face, and having a larger
diameter section at said opposite end having said integral
adapter flange: a pipe flange with a central opening
adapted for attachment to a fluid pipe for conducting
extinguishing fluid; said adapter flange being rigidly
clamped between said pipe flange and said nozzle flange; a
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sprinkler head screwed into the threaded portion of said
smaller diameter section of said central adapter passage,
; said~ sprinkler head having a spr:inkler head body with a
: central sprinkler head passage, an outside-threaded portion
f~or attachment of said sprinkler head into said adapter,
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said sprinkler head protruding into the flow of corrosive
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gases in said duct; said central sprinkler head passage
containing a seal plug at the end having said threaded
portion, a fusible fill at the end of said non-threaded
por~ion and a piston between said seal plug and said
fusible fill.
Preferably, the central sprinkler head passage in the
sprinkler head has a cylindrical portion, a shoulder and a
shoulder portion, said shoulder portion having an inside
circumferential groove of a substantial V-shape with an
angl~ of about 60, the diameter of said shoulder portion
: being larger than the diameter of said cylindrical portion,
~: said seal plug being adapted to fittingly insert in said
~ passage, said fusible fill filling said shoulder portion
; and said groove, and said piston loosely fitting in said
passage between said seal plug and said fusible fill.
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~RIEF DESCRIPTION OF DRAWINGS
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: The invention will now be described in detail with
reference to the accompanying drawings wherein:
Figure 1 is a section through the sprinkler assembly
: ~ ~attached to a duct; and
: Figu:re~2 is a an exploded vlew of the sprinkler head.
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DETAILED DESCRIPTION
In many industrial installations, highly-corrosive and
erosive substances are transferred in pipes and ducts
between operations. The nature of the substances requires
S that those pipes and ducts are made of,corrosion-resistant
materials, and in many cases such materials are plastics
such as fibreglass-reinforced resins. In order to obtain
insurance coverage for the operations, fire suppression
systems are required that can sati~factorily operate and
protect the installations and personnel.
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The present invention relates to such a system wherein the
piping carrying an extinguishing fluid (water~ are external
to ducts or pipes carrying highly-corrosive gases including
~ particulate-laden gases. The ducts have at least one,
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usuaIly a multiplicity, of sprinkler assemblies each
consisting of integral flanged nozzles mounted
perpendicularly to and in the wall of the ducts in spaced
relation, the spacing depending on the diameter of the
duct. Æach nozzle contains an adapter with a sprinkler
head. An adapter is connected to the flange on the nozzle
and to a pipe flange on a fluid pipe of the fire
uppression system. The system comprises at least one
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; fluid pipe for conducting extinguishing fluid, each pipe
connected to a sprinkler assembly.
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~ 25 The face of the adapter is substantially flush with the
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inner wall surface of the duct. The adapter has a central
passage for fluid and a sprinkler head with a fusible fill
mounted in the end of the passage, such that only a small
section of the head and the fusible fill are exposed to the
corrosive substances in the duct.
With reference now to figure 1, the sprinkler assembly
generally indicated with 10, is atSached perpendicularly to
a duct 11 (shown in part) carrying flows of highly-
corrosive gases/ that may also contain particulates, such
as, for example, encountered in gas handling systems of
metallurgical operations treating sulfide-containing
materials. Sprinkler assembly 10 is connected to a fluid
pipe 12 conducting extinguishing fluid external to duct 11.
Fluid pipe 12 has a threaded end 13 with which it is
screwed into a threaded opening 14 central in a pipe flange
15. Sprinkler assembly 10 consists of a generally
;~ cylindrical adapter 16 that has an adapter face 18 at one
end, an integral adapter flange 19 at the opposite end and
a central adapter passage 20. Central adapter passage 20
has a larger diameter section 21 at the flange side and a
short smaller diameter section 22 at the side of face 18.
The larger dlameter seotion 21 has a diameter equal to the
inside diameter of the fluid pipe 12. Adapter flange 19 is
positioned adjacent pipe flange 15. The short narrower
diameter section 22 of central adapter passage 20 has a
threaded portion 23 in proximity to adapter face 18 and
ad2pted to contain sprinkler head 100, to be described.
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~he adapter 16 is inserted in a nozzle 24 having a nozzle
flange 25 at one end and a shoulder portion 26 at the other
end. The nozzle 24 is fixedly attached at its shoulder
portion 26 in an opening in the side of and in
perpendicular direction to duct 11. T~e area of insertion
on the duct and of the nozzle i5 secured with a lay up 27,
to be defined. Adapter 16 slideably fits into nozzle 24
providing for easy insertiona
The sprinkler assembly is attached to the duct in a gas-
~ 10 tight manner by rigidly clamping adapter flange 19 between
:~ pipe flan~e lS and nozæle flange 25 with intermediate
~; gaskets 28 and 29. Clampin~ i5 done by means of four bolts
; : 30 (two are shown), each with a washer 31 and a nut 32.
~ Bolts 30 pass through corresponding apertures in the
: 15 peripheral areas of flanges lS and 2S. The diameter of
adapter flange 19 is such that flange 19 fits between the
bolts 30.
An easily replaceable spray deflector rod 33 is screwed
into the adapter face 18 of adapter 16. Rod 33 has a
straight section 34 and a bent section 35 with distal end
36, and is positioned such that distal end 36 i9 in front
: o~ and will be hit by fluid emitting from sprinkler head
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~ ~ With reference to figure 2, the sprinkler head, generally
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indicated with lO0, has a generally cylindrical sprinkler
head body lOl with a central sprinkler head passage 102.
Body 101 has an outside threaded, sliqhtly tapered portion
103 with which sprinkler head 100 is securely screwed into
threaded portion 23 of central adapter passage 20 in
adapter 16, such that the non-threaded portion of sprinkler
head 100 protrudes beyond adapter face 18.
- Central sprinkler head passage 102 in sprinkler head 100has a cylindrical portion 104 and a shoulder 105
demarcating a sprinkler head shoulder portion 106 with a
slightly larger diameter than cylindrical portion lG4.
Shoulder portion 106 has an inside circumferential groove
107. Groove 107 has a substantial V-shape with an angle
of, preferably, about 60~. The length of shoulder portion
: 15 106 is sufficient to accomodate a fu ible fill 108 made of
a fusible alloy of a thickness that is adequate to provide
the required strength against pressure exerted by the fluid
in pipe 12.
In addition to fusible fill 108, cylindrical portion 104 of
central passage 102 accomodates a piston lO9 and a seal
plug 110. $he seal plug 110 fittingly inserts in the end
~: 111 of sprinkler head 100. The piston lO9 fits loosely in
-: : central passaqe 102 from shoulder 105 to plug llO and
between fill 108 and seal plug llO. When installed in the
adapter, the piston 109 extends past the adapter face 18 of
and into the adapter 16.
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The replaceable sprinkler heads 100 are readily made by
forming a unitary fusible fill 108 to shoulder 105 in
shoulder portion 106 and groove 107, sliding piston 109
into passage 102 against fill 108 and fittingly inserting
seal plug 110 in end 111 of passage 10,2 of sprinkler head
body 101.
The materials from which the sprinkler assembly is made
should generally be corrosion-resistant as well as erosion-
resistant in environments that contain flows of acidic
gases and solids. For a sprinkler system including
sprinkler assemblies according to the invention, the fluid
pipe 12 and pipe flange lS may be made of mild steel, and
the bolts 30, washers 31 and nuts 32 of stainless steel.
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Adapter 16 and spray deflector rod 33 are preferably made
of ultra-high molecular weight polyethylene. The nozzle 24
~: i9 preferably made of fibreglass-reinforced polyester
resin, the exposed edges being resin-sealed. The lay up 27
on duct 11 and around sleeve 24 consists of fibreglass-
rein orced polyester comprising layers of mat, roving and
20~ resin (for example, HetronTM 197-P resin with W
stabilizer). Gaskets 28 and 29 are preferably made of
-~ closed-~cell foam epichlorohydrin. The sprinkler head 100
has a body 101 of lead-antimony alloy, a silicone rubber
seal plug 110 and a TeflonTM piston 109. The fusible fill
`-~ 25~ ~ 108 is made of a bismuth alloy containing 50% bismuth,
~ 26.7% lead, 13.3% tin and 10% cadmium, and having a melting
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point of 70C.
In the operation of the sprinkler assembly, air under
pressure fills the at least one fluid pipe of the dry
sprinkler system, and fills the central passage 20 in each
of the adapters up against the seal plug 110 of the
sprinkler head lO0. When temperatures higher than the
melting point of the fusible fill 108 cause melting of the
fill, pressure exerted by the air causes the seal plug llO
and piston 109 to be ejected from the sprinkler head,
thereby cleaning out passage 102 in ~prinkler head 100.
The escaping air causes pressure to drop whioh activates a
source oE pressurized water, and water rapidly fills the
: pipe 12 and emits from the sprinkler head lO0 to be broken
up into a qpray against the end 36 of deflector rod 33.
After operation is finished, the adapter 16 is removed from
each location, the sprinkler head lO0 is replaced and the
adapter is re-installed. The adapter 16 provides and has a
mass sufficient to provide an effective barrier against
heat transfer between material in duct ll and the nozzle 24
and the sprinklersystem piping, including fluid pipe 12.
The loosely-fitting piston 109 in the sprinkler head lO0
assures cleaning of and providing full bore through the
sprinkler head when ejected by air pressure after the
~:~ fusible fill 108 has melted. The piston lO9 of sprinkler
~25 head lO0 extends past adapter face l~ of adapter 16, and is
lon9 enaugh to act as an insulator and to prevent any
cooling effect to reach fusible fill 108. The seal plug
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110 provides a barrier to fluid reaching the fusible fill
108 until the system is activated, i.e., the fill has
melted. The seal plug 110 fittingly inserted in sprinkler
head 100 not only seals but is also readily pushed out of
the sprinkler head by normally-used air pressure.
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Sprinkler assemblies, constructed as described and made of
the preferred materials, were installed as part of a dry
system in small and large ducts for conveying moist, sulfur
dioxide- and solids-containing gases in a large
metallurgical operation. The adapter 16 of each sprinkler
assembly 10 has a length of 152.4 mm (6 inch) and a
diameter of 71.44 mm (2 13/16 inch3. The larger diameter
section 21 of central passage 20 through adapter 16 has a
diameter of 25.4 mm (1 inch). The central insert passage
102 through the sprinkler head 100 has a diameter of 11.7
mm (0.46 inch) and the fusible fill 108 is 4.76 mm (3/16
inch) thick and has a diameter of 14.3 mm (9/16 inch).
Groove 107 has a 60 angle and a depth of 1.2 mm (3/64
inch). T~e sprinkler head 100 is screwed into a 76.2 mm (3
inch) diameter adapter 16 (NPT thread and thread-sealing
compound) with a torque of 5.65 Nm (50 inch-pounds). This
torque provide~ a tight fit, and does not cause deformation
of the sprinkler head. The sprinkler head 100 is 30.2 mm
(1 3/16 inch) lons. The seal plug is 6.35 mm (1/4 inch)
long and the piston is 19 mm (3/~ inch) long. Fluid pipe
` ~ 12 is fllled with air undex 375 kPa ~40 psig) pressure.
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~ The response time of the sprinkler head is 120 to 150
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seconds.
It is noted that several commercially available sprinkler
heads were tested in the same environment and all failed
after a short period due to corro~ion and erosion.
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