Note: Descriptions are shown in the official language in which they were submitted.
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Head to discharge a fire fighting agent
The invention is related to a head to discharge a fire fighting agent, such
as water, in particular a fire sprinkler head comprising a plastic body.
The heads referenced to above are usually referred to as fire sprinkler
heads or simply sprinklers in case they are designed to discharge water as
fire fighting agent. Such sprinklers are an essential tool in fighting fires.
Such sprinklers comprise a fire sprinkler head connected to a water bear-
ing installation as fire fighting agent bearing installation. Since the fire
io fighting agent is typically held under certain pressure, which could
also be
a static pressure within the installation the agent, may also be referred to
as standing charge. The fire sprinkler heads are typically arranged in a
certain distance from each other. Each fire sprinkler head is constructed
as a temperature sensitive water drain, opening if the sprinkler head is
is exposed to a certain temperature. Such sprinkler is held in its closed
state
¨ its surveillance mode ¨ by a thermal detector, which depending on its
nature brakes or melts in order to release water from the installation. Then,
the sprinkler head is in its fire fighting mode. Typically with these kind of
installations the thermal detectors used comprise a glass tube filled with
20 an alcohol. The glass tubes are held in place between an abutment mem-
ber and a sealing member, which sealing member seals the water outlet,
with a predetermined torque. In order to apply the necessary pressure to
the glass tube to provide the intended sealing function, the sealing mem-
ber is manufactured from brass and the other parts of the sprinkler are
25 manufactured of metal, typical also of brass. In case such glass tube is
exposed to heat the liquid therein attends to expand and due to the raising
pressure breaks the glass at a certain pressure indicating a certain tem-
perature. These kind or thermal detectors are also referred to as frangible
bulb. The sealing member is then pushed away from its seat by the water
30 in the water bearing installation, which then flows out. In order to
distribute
the water exiting the body of the sprinkler deflection means are arranged
below the outlet opening. The deflection means are needed to brake up
the flow of water for its distribution over a certain area.
35 In WO 02/083245 Al a fire sprinkler head is disclosed, of which the body
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is manufactured by way of an injection moulding process of plastic mate-
rial. Between two plastic parts one being the moulded plastic body and the
other being a diffusor head a sealing portion is arranged. By way of the
sealing portion the outlet of a hollow central passage extending through
s the body is closed. Apart of the diffusor head is resting against the
sealing
portion and serves as an abutment. The diffusor head is held in this lock-
ing position with a link portion. The link portion is a meltable fuse element
¨ thus being sensitive to temperature. The link portion melts at a certain
temperature, which in turn releases the diffusor head from its position lock-
ing the outlet of the central passage. Due to the pressure in the installation
the sealing member then brakes and pushes the diffusor head into its dif-
fusing arrangement at a certain distance to the outlet of the central pas-
sage so that water may flow out and is distributed in the vicinity.
is The prior art fire sprinkler heads have in common, that several elements
need to be manufactured individually and then be assembled. Further, the
sprinkler heads are designed to be reusable. With those using a frangible
bulb as thermal detector these and the sealing member are replaced to
have the fire sprinkler head work again. With the device with the breakable
sealing this and the link portion are replaced.
In the light of the prior art sketched out above it is an object of the inven-
tion to provide a fire sprinkler head, which is simple in its construction and
preferably easier in its manufacturing process, but still provides for an ef-
fective temporary fire barrier.
The technical problem is solved by way of a head to discharge a fire fight-
ing agent comprising a plastic body
with means at its first end to connect the head to a fire fighting agent
bearing installation;
with a central passage extending through the connection means into
a discharge section of the body; and
with at least one discharge opening connecting the central passage
of the discharge section with the outside of the body, which discharge
opening is closed in the surveillance mode of the head and which dis-
charge opening is open for the release of fire fighting agent in its fire
fight-
ing mode, whereas the cross sectional area of each of the at least one
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discharge opening is smaller than the cross sectional area of the central
passage extending through the connection means,
which discharge opening is closed by a thermal sensitive locking
member failing upon heat exposure easier than the body, thereby opening
the discharge opening for the release of fire fighting agent, which tempera-
ture sensitivity of the locking member is designed that it fails at a prede-
termined temperature.
This head comprises one or more predetermined breaking areas, which in
io the surveillance mode of the head lock the discharge openings and which
break by failing for example by melting at least in part upon the exposure
of heat. These breaking areas are referred to as locking members. The
thermal sensitive locking member closing a discharge opening is designed
to fail at a predetermined temperature, which temperature is well above
is the maximum ambient temperature, in which the head is to be arranged.
Typically the failing temperature may be designed that the locking member
melts upon a heat exposure being approximately 30 C above the maxi-
mum ambient temperature level. Of course, other temperature levels may
be applied in the same manner. The temperature sensitivity of the locking
20 member being the thermal detector of this sprinkler head is designed
that
it melts earlier and/or quicker than the body of the head being manufac-
tured of plastic material.
The thermal sensitivity of the locking member as sketched out above may
25 even be achieved by using one and the same plastic material for the body
and the locking member. The thermal sensitivity may be achieved by pro-
viding the locking member with a thinner wall thickness compared to the
wall thickness of the body in the area adjacent to such discharge opening.
The quicker response characteristic of the locking member to heat expo-
30 sure may also be achieved in that the outside surface of the locking mem-
ber is designed to have a higher heat absorbing character than the surface
areas of the body adjacent to such locking member. Such quicker heat
response characteristic may be achieved by providing the outside surface
of the locking member with a bigger surface area, for example providing it
35 with a higher roughness and/or by providing the outside of the locking
member with a heat absorbing colour. The adjacent areas of the body
would then accordingly show a lower degree of roughness and/or a heat
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reflecting or less heat absorbing colour or coating of such kind.
One of the major benefits of this concept is, that the head may be manu-
factured by way of a moulding process, which is preferably an injection
s moulding process, without that any further assembly steps need to be car-
ried out. Therefore the process for manufacturing such head is to be re-
garded as a low cost manufacturing process, thus providing heads on a
low cost base.
io Due to the concept described it is possible to design the one or
typically
more discharge openings with thermal sensitive locking members closing
the openings with a high degree of freedom to design the openings and
their distribution in the body of the head. This makes its possible that the
discharge openings are designed with a cross sectional area, small
is enough that for example with use of water as fire fighting agent the
pres-
surised water of the water bearing installation, to which the sprinkler head
is joined, exits in the form of small size water jets or even as spray. There-
fore basically with this head it is not necessary to provide for a deflection
member to break up the flow of water to be distributed as is necessary
20 with prior art heads.
Further, with this concept it is easy to provide with virtually one and the
same moulding tool a heads with discharge openings closed by thermal
sensitive locking member, which discharge openings are arranged at dif-
25 ferent positions. As such it is for example possible to design the
discharge
section of the head with discharge openings arranged in an annular ar-
rangement as a first alternative and simply by slightly amending the
moulding surface provide a head with its discharge openings arranged
only in a certain section, for example extending only over a semi-circle or
30 even less.
An interesting aspect of the concept claimed is that the difference in the
failing response upon heat exposure between the at least one looking
member and the other parts of the body does not necessarily be very
35 large. The plastic material used and the geometry of the body is
designed,
that it retains its integrity until the at least one locking member melts and
thereby opens its discharge opening. Then, the fire fighting agent of the
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installation, to which the head is joined will flow through the body, thereby
cooling the body from its inside. The best cooling effects may be achieved,
if the fire fighting agent is a liquid, in particular water. The fire fighting
agent in the installation is well below the failing point of the locking mem-
ber. Therefore, even upon exposure to heat above the failing point of the
plastic used to manufacture the body it will retain its integrity due to the
cooling effect of the agent flowing through the body. A head of this kind
may thus be manufactured from a plastic material, which does not neces-
sarily be of the usual kind used for high temperature applications. There-
fore, such head may be manufactured from a plastic material, which is
cheaper than heat resistant plastic material.
The thermal sensitive locking member closing the discharge openings in
the surveillance mode of the head may also be manufactured from another
is plastic material than the body, for example by way of a two or more com-
ponent moulding process. With such embodiment a plastic material of
higher temperature resistance may be used for the body than the one
used to resemble the thermal sensitive locking members.
The heads described above are very effective in building a temporary fire
barrier. Since with this concept heads may be designed as spray nozzles
the water exiting such head exits this with a rather large surface area. With
this smoke and dust may be tied down to a certain degree. Further, the
large surface area of the water exiting the head enhances its vaporisation,
which is one of the effects to provide for an effective fire barrier.
The connecting means to connect the head to a water bearing installation
will typically be designed as a threaded section to be screwed into an
opening with a complementary threaded section of the installation. Of
course, other connection means like bajonett-couplings or the like may
also be used.
Should a tool be needed to fasten the sprinkler head to the installation,
according to a preferred embodiment the body of the sprinkler head shows
one or more tool application faces. These are arranged to make up a tool
application section of the body enabling to place a tool and then introduce
the necessary torque to fasten the sprinkler head to the installation.
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The head may virtually be used with many different kinds of fire fighting
agent bearing systems. Therefore its use is not only limited to a use in
buildings. In particular due to its compact size it may also be used for ex-
ample with combustion engines having a cooling circuit to cool the engine.
The liquid therein is then to be regarded as the fire fighting agent. Having
employed one or more of these fire sprinklers in the cooling system of a
combustion engine, an automatic fire fighting system may be established,
to target high risk areas of the engine and/or the system. In a building the
io heads may be used instead of the usual sprinkler heads arranged in the
ceiling or in the walls. According to another embodiment of use of such
heads these are joined to the water bearing heating installation. In such
application a sprinkler head may be arranged in the radiator opening, in
which usually the venting plug is arranged. With such application the head
is may also provide the functionality of venting the water bearing system,
for
example the radiator. Should the head be designed with a threaded sec-
tion as connections means, then the venting functionality may be realised
by way of a groove cutting across the threads of the threaded section. The
groove will preferably not cut across all threads in the longitudinal exten-
20 sion of the threaded section but leave one or more windings of the
thread
opposite to the distal end of the threaded section uncut. The head may be
used as a venting plug in the same manner as conventional venting plugs,
but with the further fire fighting functionality.
25 Further at advantages and embodiments will become apparent with the
description of an embodiment of the invention under reference to the fig-
ures. These depict:
Fig. 1: as side elevational view of a head according to a first em-
30 bodiment of the invention,
Fig. 2: a longitudinal cross section of the head of figure 1,
Fig. 3: an enlarged detail of the cross sectional view of the head of
35 figure 2,
Fig. 4: a top view of the head of figure 1,
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Fig. 5: a bottom view of the head of figure 1, and
Fig. 6: a cross sectional view depicting another embodiment accord-
ing to the invention.
A head 1 to discharge a fire fighting agent is according to the depicted
embodiment manufactured as one sole solid device. The head 1 com-
prises a body 2. The body 2 of the head 1 is in the embodiment depicted
io in figure 1 divided into three sections, namely a threaded section 3 as
connecting means to connect the head to a fire fighting agent bearing in-
stallation, a discharge section 4, through which water exits in the fire fight-
ing mode of the head 1, and a tool attachment section 5. The tool attach-
ment section 5 is used to apply a tool to the body 2 in order to screw the
is body 2 with its threaded section 3 into an opening comprising a comple-
mentary threaded section of a fire fighting agent bearing installation. In the
present embodiment the tool attachment section 5 is provided by way of
six side faces facing in the radial direction and arranged according to a
hexagon. Thus, a nut or a wrench may be applied to the tool attachment
20 section 5 in order to apply the torque needed to screw the threaded sec-
tion 3 of the head 1 into an opening of the installation. The head 1 is
manufactured by way of an injection moulding process form a plastic ma-
terial. In the depicted embodiment polypropylene has been used to manu-
facture the head 1.
The head 1 is intended to be used with a water bearing installation. There-
fore, in the following by way of the described example the fire fighting
agent is water. It will be well understood, that also other fire fighting
agents, like other fluids or gases or mixtures thereof (foams) may be em-
ployed.
As to be seen from the longitudinal cross section of figure 2 the head 1
comprises a central passage 6, which extends through the threaded sec-
tion 3 and is open at the distal end 7 of the threaded section 3. When con-
nected to a water bearing installation water will enter the central passage 6
of the body 2 of the head 1. The central passage 6 leads into a cavity 8
having its maximum diameter in the discharge section 4. The central pas-
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sage 6 and the cavity 8 are rotation-symmetric, thus show a circular cross
sectional geometry. The cavity 8 may be understood as a manifold.
The discharge section 4 of the depicted embodiment comprises four dis-
charge openings 9, which are closed in the surveillance mode of the head
1. The surveillance mode of the head 1 is the mode, in which no water ex-
its the head 1. The surveillance mode of the head 1 is distinguished from
its fire fighting mode, in which water exits the head 1 through the dis-
charge openings 9. It is to be understood, that in the fire fighting mode the
io discharge openings 9 are at least partways open.
In the present embodiment the discharge openings 9 are closed to have
the head 1 in its surveillance mode. The discharge openings 9 are closed
by thermal sensitive locking members 10, which may also be addressed
is as thermal detectors. In the embodiment depicted in figures 1 to 5, the
locking members 10 are provided by a thinning of the wall thickness of the
discharge section 4 as better to been seen in the enlarged detail of figure
3. The thinning is worked in the present embodiment with a concave
shape at the outside surface of the discharge section 4. The body 2 and
20 as such the wall 11 of the discharge section 4 and the locking members
10
as part of the wall 11 are manufactured from one and the same plastic ma-
terial.
The locking members 10 show a higher temperature sensitivity, which
25 means, that these respond to heat exposure with thermal failure faster
than the rest of the body 2 and in particular the wall 11 of the discharge
section 4. Since the wall 11 and the locking member 10 are manufactured
of one and the same plastic material the failing point as such of the plastic
material resembling the locking members 10 and the other parts of the
30 body 2 of the head 1 is the same. In order to ensure, that the locking
members 10 show a higher temperature sensitivity and thus fail before the
rest of the body looses its integrity, the thickness of the locking member 10
is reduced compared to the thickness of the adjacent walls 11. In the em-
bodiment depicted the wall thinning reduces the thickness of the wall 11 in
35 a maximum of a little more than 50 %. Already from this measure it will
become apparent, that upon heat exposure even if the outside of the wall
11 should start to melt, the locking members 10 will fail well before any
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other portion of the wall 11 fails. This is to be attributed to the wall
thinning.
Since the installation, to which the head 1 is joined to is water bearing and
since the water in such installation is typically under pressure from the in-
side of the locking members 10 the pressure within the installation is work-
s ing against the locking members 10. Therefore the fail of the locking mem-
bers 10 is initiated by heat exposure, but is supported by the water pres-
sure within the cavity 8 of the body 2. It is not necessary, that the locking
member 10 melts completely, before water is discharged through the dis-
charge openings 9. It is only necessary, that the locking members 10 are
io due to the heat they are exposed to, they weaken sufficiently, that they
cannot withstand the pressure within the installation and in the cavity 8.
Then the locking members 10 exposed to thermal and pressure effects fail
open and the discharge openings 9 are open. The head 1 is then in its fire
fighting mode. From the forgoing it will be apparent, that the fire fighting
is mode cannot be reversed to the surveillance mode. Therefore, once the
head 1 has been brought into its fire fighting mode, have to be replaced.
Already the concave geometry of the locking members 10 enhances col-
lecting more heat due to be bigger surface area than the adjacent sections
20 of the wall 11. In the depicted embodiment as a further measure to have
the locking member 10 respond to heat and fail more rapidly than the ad-
jacent sections of the wall lithe outside surface 12 of the locking mem-
bers 10 is roughened. This enlarges the outside surface area of the lock-
ing members 10, thereby collecting more heat. The outside surface 13 of
25 the wall 11 in contrast is provided with a polished surface which
reflects
the radiant heat. As a further possible measure the outside surface of the
locking members 10 could be provided with a colour, which absorbs more
heat than the colour on the outside surface 13 of the adjacent wall 11.
30 As to be seen from the top view of the head 1 of figure 4 the four dis-
charge openings 9 are arranged according to an annular geometry, each
discharge opening 9 being spaced form its neighbouring discharge open-
ing by an angle of 90 .
35 The embodiment depicted in figures 1 to 5 may also be used as a venting
plug. In order to achieve this further functionality of the head 1 a venting
groove 14 is arranged within its threaded section 3. In the depicted em-
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bodiment the venting groove 14 extends parallel to the longitudinal exten-
sion of the threaded section 3. The venting groove 14 cuts the threads of
the threaded section 3 beginning at the distal end 7 thereof. The groove
14 does not cut all threads but leaves one or two windings at the other end
of the threaded section 3 uncut. When the head 1 is introduced for exam-
ple into a water bearing radiator air can escape through the air venting
groove 14, if the threaded section is not screwed into the complementary
opening of the radiator to its end, thus giving by way of the air venting
groove 14 a path, on which air within the installation may escape. In the
present embodiment the air venting groove 14 as a V-cross sectional ge-
ometry as to be seen in the bottom view of figure 5 of the head 1. If the
head 1 is screwed with this threaded section 3 completely into the com-
plementary opening of the installation, then the air passage of the venting
groove 14 is blocked.
Instead of a groove as described above also a tapered thread may be ap-
plied to provide the air path needed for such venting functionality.
In case a sealing arrangement between the head 1 and the installation
cannot be achieved by the properties of the plastic material of the body 2,
a sealing ring may be placed under the annular flange 15 of the tool at-
tachment section 5 facing to the distal end 7 of the threaded section 3.
The same measure could be taken, in case the head is exposed to exces-
sive vibration. Therefore the further descriptions referring to such ring as a
sealing ring are also applicable for the use of such ring as a dampening
ring. Such sealing ring may be manufactured as a one solid piece with the
body 2 by employing a two component moulding process. In a first shot
the body 2 would be manufactured from a first plastic material. In a second
injection shot the sealing ring would be manufactured with another plastic
material having the properties needed to provide the intended seal func-
tionality. Such sealing ring may also be used as a vibration damper and/or
device to hinder that the mounted head loosens, in case the water bearing
installation is used to vibrate like this is the fact with combustion engines
and their cooling circuit.
In case the head 1 and its discharge section 4 respectively is exposed to
heat the locking members 10 due to their geometry and the further meas-
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ures sketched out above will fail once they have been heated up to a cer-
tain temperature. This temperature is approximately 30 C higher than the
maximum operating temperature the locking members 10 are confronted
in the surveillance mode of the head 1. Since the head 1 is adapted to be
s used as a venting plug in a water bearing heating installation, which
could
be a heating water installation the temperature of fail of the locking mem-
bers 10 will be approximately 30 C higher than the maximum operating
temperature of the water in the heating system, which temperature is as-
sumed to be higher in its maximum temperature than the temperature at
io the outside of the head 1. Due to the concave geometry of the locking
members 10 the fail will most probably initiate at the point, where the lock-
ing members 10 show their smallest wall thickness. Then, supported by
the pressure within the installation the discharge openings 9 are opened.
These basically will be smaller in diameter than the diameter of the locking
is members 10. Thus, the discharge openings 9 then open are small sized to
allow water exiting by way of small sized spray.
Figure 6 shows a head 1.1 in its longitudinal section according to another
embodiment. The head 1.1 is principle designed as the head 1 described
20 to figures 1 to 5. Therefore the descriptions of the head 1 also apply
to the
head 1.1. The head 1.1 differs from the head 1 in that the locking mem-
bers 10.1 are manufactured of a different plastic material than the rest of
the body 2.1. The head 1.1 is manufactured by way of a two component
injection moulding process, whereas in a first shot the body 2.1 without the
25 locking members 10.1 is manufactured. In a second injection moulding
step the plastic material resembling the locking members 10.1 is intro-
duced into the discharge openings, closing them. The plastic material of
the locking members 10.1 show a lower failing point than the plastic mate-
rial, of which the other part of the body 2.1 is manufactured from. The prin-
30 cipal of work of this head 1.1 is identical to the one described above
with
reference to figures 1 to 5.
From the forgoing description of the invention it will have become appar-
ent, that there are numerous measures to be taken individually or in com-
35 bination with each other to provide locking members, which fail more
quickly when exposed to heat than the adjacent parts of the body of the
head. These measures are:
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¨ wall thinning;
¨ providing the outer surface geometry of the locking members with
an enlarged surface geometry, being for example concave;
¨ providing a difference in surface roughness between the outside
surface of the locking members and the adjacent outside surface of
the discharge section, whereas the outside surface of the locking
member shows a higher roughness than the adjacent surface;
¨ providing the outside surface of the locking members with a heat
absorbing colour. In such embodiment it is preferred, that the out-
side surface of the adjacent wall portions are provided with a less
heat absorbing colour or finishing;
¨ providing locking members manufactured from a plastic material
having a lower failing point than the adjacent parts of the body.
is Providing
the head 1 with rather small sized discharge openings 9 when in
their open mode has the further advantage, that the water supplied by the
water bearing installation does not flow out as fast as this is used to be
observed with conventional heads. This is another measure, which en-
hances the vaporisation of the water and therefore supports the build up of
an effective fire barrier.
With the possibilities of injection moulding the discharge openings may be
designed with a non-uniform cross-sectional geometry and/or are a in the
direction of their longitudinal axis. It is therefore possible to provide a
cone-like geometry of the discharge opening becoming smaller in the di-
rection to the outside and thus designing a discharge opening similar to an
orifice. This results in a higher efficiency rate of release.
The invention disclosed may be employed in numerous other manners.
The specific description of the embodiment is only a description of possi-
ble embodiments. Therefore the disclosure is not limited to these embodi-
ments.
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Reference numerals
1, 1.1 fire sprinkler head
2, 2.1 body
3 threaded section
4 discharge section
tool attachment section
6 central passage
7 distal end
8 cavity
9 discharge opening
10, 10.1 locking member
11,11.1 wall
12 surface
13 surface
14 groove
flange
