Note: Descriptions are shown in the official language in which they were submitted.
INERT GAS REMOTE DRIVER LIQUID FIRE SUPPRESSION SYSTEMS
CROSS-REFERENCE TO RELATED APPLICATION
[0001] Benefit is claimed of U.S. Patent Application No. 62/610,032,
filed December 22,
2017, and entitled "Inert Gas Remote Driver Liquid Fire Suppression Systems",
the
disclosure of which is incorporated by reference herein in its entirety as if
set forth at length.
BACKGROUND
[00021 The disclosure relates to fire suppression. More particularly,
the disclosure relates
to systems using liquid agents.
[0003] Hydroflourocarbon (HFC) agents have been used for decades. Halon
1301
(bromotrifluoromethane) is a key such HFC. These are in disfavor due to
environmental
concerns.
[0004] Among recent replacements for HFC agents, 3MTm NovecTM 1230 fire
protection
fluid (3M, St. Paul, Minnesota) is a fluoroketone named dodecafluoro-2-
methylpentan-3-one
(CF3CF2C(0)CF(CF3)2). Its ASHRAE nomenclature is FK-5-1-12. In the KiddeTM
ADSTM
fire suppression system (Kidde-Fenwal, Inc., Ashland, Massachusetts), this
agent is used with
an N2 propellant. Normally stored as a liquid, the low heat of evaporation and
high vapor
pressure (e.g., relative to water) means that the agent will rapidly vaporize
at discharge from
the nozzle outlets and be delivered as vapor.
[0005] An increasing number of applications for fire suppression suffer
from use of
chemical suppressants. For such applications, essentially inert gaseous
suppressants are used.
These include argon, nitrogen, and their mixtures. Commercially available
argon-nitrogen
suppressants include a 50-50 by weight N2/Ar mixture and a 52-40-8 by weight
N2/Ar/CO2
.. mixture. These are typically stored at a pressure of about 200 bar to 300
bar (e.g. at typical
room temperatures such as an exemplary reference temperature of 15 C or 21 C).
A
particularly significant application for inert suppressants is automatic fire
extinguishing
systems for server rooms, data centers, and the like.
SUMMARY
[0006] One aspect of the disclosure involves a fire suppression system
comprising: a gas
source and at least one vessel containing a liquid suppressant. A respective
flowpath extends
from each said vessel to one or more associated first outlets. A respective
propellant flowpath
extends from the gas source to each said vessel and is coupled to a headspace
of the vessel.
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At least one first pressure reducing device and at least one second pressure
reducing device
are in series along the propellant flowpath between the gas source and the at
least one vessel.
[0007] In one or more embodiments of any of the foregoing embodiments,
the at least
one first pressure reducing device comprises a plurality of first pressure
reducing devices not
in series.
[0008] In one or more embodiments of any of the foregoing embodiments,
the at least
one vessel is a plurality of vessels and the at least one second pressure
reducing device is a
plurality of second pressure reducing devices respectively in series with an
associated vessel
of the plurality of vessels.
[0009] In one or more embodiments of any of the foregoing embodiments, the
gas source
is at a pressure of at least 100 bar.
[0010] In one or more embodiments of any of the foregoing embodiments,
the gas source
is at a pressure of 100 bar to 300 bar.
[0011] In one or more embodiments of any of the foregoing embodiments,
the gas
comprises at least 70% by weight argon, nitrogen, or combined argon and
nitrogen.
[0012] In one or more embodiments of any of the foregoing embodiments,
other than said
argon and/or said nitrogen and other noble gases and carbon dioxide, if any,
the gas
comprises no more than 5% by weight all other constituents total.
[0013] In one or more embodiments of any of the foregoing embodiments,
the gas
comprises at least 30% each of nitrogen and argon by weight.
[0014] In one or more embodiments of any of the foregoing embodiments,
the gas source
comprises a plurality of cylinders in parallel.
[0015] In one or more embodiments of any of the foregoing embodiments, a
controller is
configured to independently control flow from the respective cylinders.
[0016] In one or more embodiments of any of the foregoing embodiments, the
fire
suppression system of claim 1 further comprises a plurality of second outlets
and respective
flowpaths from the gas source to the second outlets not passing through any
liquid
suppressant body.
[0017] In one or more embodiments of any of the foregoing embodiments, a
method for
using the fire suppression system comprises for one or more of the at least
one vessel:
opening a valve to pass the gas along the propellant flowpath to pressurize
the headspace and
propel the liquid suppressant along the flowpath from the vessel to the one or
more associated
first outlets.
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[0018] In one or more embodiments of any of the foregoing embodiments,
the opening of
the valve leaves closed other valves so as to not discharge suppressant from
one or more
others of the at least one vessel.
[0019] In one or more embodiments of any of the foregoing embodiments,
in addition to
the opening of the valve, the method includes opening another valve to
directly discharge the
gas via one or more second outlets.
[0020] In one or more embodiments of any of the foregoing embodiments,
the gas
comprises at least 70% by weight argon, nitrogen, or combined argon and
nitrogen.
[0021] Another aspect of the disclosure involves a fire suppression
system comprising a
.. gas source and at least one vessel containing a liquid suppressant. A
respective first flowpath
extends from the gas source through each said vessel to one or more first
outlets. A respective
second flowpath extends from the gas source to one or more second outlets. At
least one first
pressure reducing device and at least one second pressure reducing device are
in series along
the first flowpath between the gas source and the at least one vessel. The
second flowpath
.. does not pass through a vessel containing liquid suppressant.
[0022] In one or more embodiments of any of the foregoing embodiments,
the gas source
is at a pressure of 100 bar to 300 bar.
[0023] In one or more embodiments of any of the foregoing embodiments,
the gas
comprises at least 70% by weight argon, nitrogen, or combined argon and
nitrogen.
[0024] In one or more embodiments of any of the foregoing embodiments, the
gas
comprises at least 30% each of nitrogen and argon by weight.
[0025] In one or more embodiments of any of the foregoing embodiments,
along each
first flowpath there may be a respective burst disk between each said vessel
and the
associated one or more first outlets.
[0026] The details of one or more embodiments are set forth in the
accompanying
drawings and the description below. Other features, objects, and advantages
will be apparent
from the description and drawings, and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 is a schematic view of a fire suppression system.
[0028] FIG. 2 is a schematic view of a first endpoint of the system.
[0029] FIG. 3 is a schematic view of a second endpoint of the system.
[0030] Like reference numbers and designations in the various drawings
indicate like
elements.
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DETAILED DESCRIPTION
[0031] FIG. 1 shows a fire suppression system 20 having an inert gas
(e.g., argon and/or
nitrogen-based) source 22. An exemplary inert gas source comprises a plurality
of inert gas
cylinders 24. These are typically stored at a pressure of about 200 bar to 300
bar (e.g. at
typical room temperatures such as an exemplary reference temperature of 15 C
or 21 C),
more broadly 100 bar to 300 bar or 150 bar to 300 bar. These may be gage or
absolute
pressures. Subsequent pressures downstream discussed below are gage pressures.
[0032] The exemplary cylinders are coupled in parallel via a supply
manifold 26. Each
exemplary cylinder has an outlet 28 (e.g., threaded fitting). For each
cylinder, one or more
control valves and/or controllable pressure regulators (individually or
combined in function
and hereafter "devices") 30 may intervene between the outlet 28 and a
corresponding port on
the supply manifold 26. The devices 30 may be controlled by a controller 200.
Exemplary
pressure regulation by the devices 30 is to about 70 bar, more broadly 50 bar
to75 bar. This
allows use of lower pressure capability ANSI Schedule 40 plastic
piping/fittings downstream.
[0033] The exemplary supply manifold 26 has an outlet port connected to a
main feed
line 32 which, in turn, connects to the inlet port of a distribution manifold
34. The
distribution manifold 34 has outlets ultimately feeding individual end points
shown as 36A-G
(collectively or individually 36). As is discussed further below, the end
points may have one
or more of several different configurations. These different configurations
may occur in
different installed systems or may coexist at different locations (e.g., rooms
or locations
within rooms) in a given system installation. Each end point 36 is at the end
of a respective
delivery line 40A-G (collectively or individually 40). As is discussed further
below, the end
points themselves may represent single or multiple outlets.
[0034] Each of the exemplary lines 40A-G contains a selector valve 42.
The selector
valves 42 may be connected to and controlled by the controller 200 as are the
devices 30.
Exemplary selector valves are simple on-off valves such as solenoid valves.
Exemplary
solenoid valves are electro-pneumatic solenoid valves such as the Type 400
valve of Muller
Gas Equipment A/S, Vollerup, Denmark. Depending upon the nature of the end
points 36, the
associated lines 40 may have pressure regulating devices 44. Exemplary devices
44 may
range from simple fixed orifices, to manually adjustable pressure regulators
(e.g., shutter-
style pressure gages ¨ the manual adjustment may be made in the factory
manufacturing the
fire suppression system and, in the factory, locked in for safety), to
controllable pressure
regulators controlled by the controller 200. The orifice size of fixed
orifice, or the adjusted or
controlled restriction or pressure (of an adjustable or controllable device,
respectively), may
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be tailored to the particular type and size of end point 36. In general, the
devices 44 may be
effective to limit downstream pressure to a value in the vicinity of 10 bar to
45 bar. This may
represent a delta across the device 44 of at least 5 bar or at least 10 bar.
The particular
regulated pressure will depend on the nature of the agent to be dispensed
(discussed below).
[0035] Flowpaths from the vessel(s) to the endpoints (or outlets thereof
discussed below)
allow for controlled discharge of suppressant. The various flowpaths may thus
partially
overlap with each other. Multiple valves, pressure regulators, and the like
may be located
along said flowpaths at various places in the system to allow an appropriate
amount of
suppressant to be delivered to the appropriate nozzles while potentially not
discharging from
other nozzles. The system may further include sensors (not shown - e.g., heat,
smoke, and the
like), and switches or other interfaces (not shown) to allow a commanded
discharge. The term
"flowpath" may apply to an overall flowpath from a gas cylinder to an outlet
or to one or
more segments of such overall flowpath.
[0036] Some of the end points (e.g., 36A and 36B in FIG. 1) may merely
discharge the
inert gas as a suppressant rather than as a propellant for another agent. FIG.
2 discloses one
example of such an end point wherein a discharge manifold 50 has an inlet at
the end of line
40A and a plurality of outlets feeding respective nozzles 52. The nozzles 52,
in turn, have
outlets 53 discharging inert gas flows 54. Examples of locations protected by
inert gas only
are computer server rooms, computer server room subfloors, ship engine rooms,
control
rooms, museum display cases, and museum gallery rooms (to protect paintings
and other
artwork) and other locations typically protected by halocarbons. In such
situations, the
distribution manifold pressure may be essentially (subject to piping losses)
passed to the
nozzle outlets.
[0037] Other end points may involve additional suppressants or agents
whose flow is
driven (propelled) by the inert gas from the source 22.
[0038] For example, FIG. 3 shows an exemplary end point 36G having a
vessel 60
containing a body of liquid agent 62. A discharge conduit 64 has an inlet 66
immersed well
below a surface 68 of the liquid 62. The vessel has a headspace (ullage space)
69 which may
be pressurized via the line 40G to, in turn, drive/propel the agent into the
inlet 66 and through
the conduit 64 to a distribution manifold 70 and therefrom as discharge flows
74 from outlets
73 of nozzles 72. The flowpath through said vessel 60 may be considered as
having a
propellant flowpath or leg extending to the vessel and a discharge flowpath or
leg extending
from the vessel. In contrast, the gas flowpaths for the endpoints 36A and 36B
are only gas
flowpaths and do not pass through any vessel containing or formerly containing
liquid agent.
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[0039] A burst disk or other device 76 may be locally along the line 64.
Depending on the
nature of the agent, it may be stored at zero gauge pressure or at a slight
positive gauge
pressure (e.g., up to about 5.5 bar (e.g., about 5 bar for HFC 227, about 0.7
bar for NovecTM
halocarbon, or close to zero for aqueous agents).
[0040] The disk 76 ruptures at a first pressure above the storage pressure
of the liquid 62
in the vessel 60 (e.g., by at least 0.5 bar above agent vapor pressure or an
exemplary 0.5 bar
to 10 bar or an exemplary 6 bar to 8 bar). Thus, when the associated valve 42
(shown in FIG.
1) is opened (and pressure is being supplied by one or more open devices 30),
the inert gas
fills the headspace 69 pressurizing the vessel 60 until the threshold of the
burst disk 76 is
overcome. Upon overcoming the burst disk threshold pressure the inert gas
drives/propels the
agent 62 out through the burst disk and outlets 73 of nozzle(s) 72.
[0041] FIG. 3 also shows an upstream burst disk 78 at the gas inlet to
the vessel 60. This
disk 78 may be positioned to seal the line 40 upstream. This may avoid
contamination of the
line by vapor from the vessel 60, and may generally have a similar rupture
pressure
(threshold) to the disk 76. Alternatively, 78 may represent a check valve such
as a pilot check
valve. As noted above, the device 44 may be configured to provide desired
operating pressure
for such an end point. Exemplary such pressure is discussed above and further
below.
Exemplary agent 62 and exemplary use situations are discussed below.
[0042] By keeping the storage and use pressure in the vessel 60
relatively low, it need not
be configured as a high pressure vessel (e.g., a pressure cylinder). Rather,
greater flexibility
in packaging may be had to fit a desired amount of agent in a given available
space. For
example, an engine compartment for an air handler system, which has open space
but of 15
liters but could not accommodate a standard 15-liter steel cylinder. Custom
vessels may be
made of steel, aluminum or composites (e.g., carbon fiber or glass fiber).
[0043] For a given type of end point, there may be different sizes. For
example, a kitchen
system will be sized to the stove type and size and expected type of fire
(e.g., gas grills vs.
fryers typically present different fire hazards). Likewise a subfloor that
uses halocarbon could
be of narrow height but wide area, for example, a shallow 1-foot (30cm) tall
but large 30 foot
by 30 foot (9 m by 9 m) area, and would need agent storage sized accordingly
(e.g., about
240 liters at 300 bar). This would scale with room size.
[0044] An exemplary kitchen system (endpoint) uses a water-based agent.
An exemplary
agent is AquaGreen XTTm aqueous agent (Kidde-Fenwal, Inc., Ashland,
Massachusetts).
Exemplary aqueous agents are 40% to 70% by weight water, and the remainder
mainly
inorganic salts plus chelating agents, typically with only impurity levels of
any other
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components. These will operate at relatively low pressure (e.g., 10 bar to 14
bar, more
narrowly, 12 bar to 14 bar, provided by the pressure regulator 44). They
remain liquid when
discharged.
[0045] Another such end point is one with high value equipment (e.g.,
computer server
.. rooms, data centers, engine rooms, and mechanical control rooms) where
aqueous agents risk
damaging equipment. Exemplary non-aqueous agents are NovecTM or other
halocarbons.
Exemplary pressures are 25 bar to 35 bar, more broadly 25 bar to 65 bar or 25
bar to 60 bar
provided by the regulator 44. Typically due to the need to vaporize and
disperse the vapor,
pressures will be higher than the pressure used for aqueous agent.
[0046] Yet further end points may be configured to discharge mixtures of
the inert gas
and some other material. For example, halocarbon agents used in configurations
such as FIG.
3 will tend to absorb some of the propellant so that a mixture is discharged.
Other situations
may involve specifically configuring the end point so that a flow of the
propellant entrains
liquid or solid agent.
[0047] The controller may be configured to stop flow to an end point when
the agent is
expended and or the occurrence of another condition. The expending may be
determined by
programming (the controller knows how long flow could be maintained for the
available
agent) or by a sensor (e.g., a liquid level sensor in the vessel). The other
condition may be a
sensed room condition such as temperature dropping to a threshold level.
[0048] In sustained inerting situations, the system may be configured to
discharge inert
gas after all agent 62 is expended. Thus, the gas may transition from being
merely or
principally a propellant (for agent 62) in a first stage of operation from a
given end point to
being the suppressant/agent in a subsequent stage of operation at that end
point. See,
PCT/US2017/067641, (the WO '641 application), of Carrier Corporation, filed
December 20,
2017, and entitled "FIRE PROTECTION SYSTEM FOR AN ENCLOSURE AND
METHOD OF FIRE PROTECTION FOR AN ENCLOSURE", the disclosure of which is
incorporated by reference herein in its entirety as if set forth at length. In
such a situation, the
gas from the present source 22 would serve as the "inert agent" of the WO '641
application
and the present liquid agent 62 would serve as the "primary agent" of the WO
'641
application. Similar operational parameters, sensors and control algorithms to
those of the
WO '641 application could thus be used.
[0049] Multiple valves, pressure regulators, and the like may be located
at various places
in the system to allow an appropriate amount of suppressant to be delivered to
the appropriate
nozzles while potentially not discharging from other nozzles. The system may
further include
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sensors (not shown - e.g., heat, smoke, and the like), and switches or other
interfaces (not
shown) to allow a commanded discharge.
[0050] As noted above, exemplary inert propellants are argon and/or
nitrogen-based. For
example, the propellant may comprise at least 70% (or at least 80% or at least
85%) by
weight argon, nitrogen, or combined argon and nitrogen. Exemplary argon-
nitrogen blends
may include at least thirty weight percent each of argon and nitrogen.
Nevertheless, more
uneven blends are possible. Carbon dioxide is one additional component that
may be present
in more than trivial levels. Thus, for example, beyond argon and/or said
nitrogen and other
noble gases and carbon dioxide, if any, the propellant may comprise no more
than 5% ( or no
.. more than 2%) by weight all other constituents total and/or no more than 2%
(or no more
than 1%) such other constituents individually.
[0051] FIG. 1 further shows a controller 200. The controller may receive
user inputs from
an input device (e.g., switches, keyboard, or the like) and sensors (not
shown, e.g., smoke
and/or temperature sensors at various building locations and condition sensors
at various
.. locations in the system (e.g., gas pressure sensors)). The controller may
be coupled to the
sensors and controllable system components (e.g., valves and the like ¨ not
shown) via
control lines (e.g., hardwired or wireless communication paths 202). The
controller may
include one or more: processors; memory (e.g., for storing program information
for execution
by the processor to perform the operational methods and for storing data used
or generated by
the program(s)); and hardware interface devices (e.g., ports) for interfacing
with input/output
devices and controllable system components.
[0052] The system and its components may be made using otherwise
conventional or
yet-developed materials and techniques. Operation may also reflect existing
techniques,
particularly when viewed at the level of the operation of a given end point.
Overall operation
may comprehend the controller being programmed to selectively open an
appropriate
combination of the devices 30 to provide a required propellant flow. For
example, responsive
to sensed fire, heat, smoke, or the like, and/or responsive to manual
triggering, the controller
200 may be programmed/configured to engage/discharge a given combination of
the end
points 36 by opening their respective valves 42. The controller may calculate
required gas
flow for that combination (e.g., based upon a stored table or database of flow
values for each
end point). The controller may open an appropriate number of devices 30 to
provide this
simultaneously with commanding opening the valve(s) 42. In an exemplary
situation with
electro-pneumatic selector valves 42, actual opening of the valve 42 to pass
flow is slightly
delayed because it is driven by the pressure introduced upstream via the
devices 30.
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[0053] Depending upon the implementation, various real-time modification
of the
propellant flows via the devices 30 may be made. For example, in some
implementations,
flow from one cylinder might be effective to run the necessary end points for
only a portion
of a period of time (e.g., not all agent will have been expended). In response
to a sensed
pressure drop or calculated expenditure, the controller may subsequently open
a further one
or more cylinders to maintain required flow.
[0054] Similar adjustments may be made in the case of failures or leaks.
These failures or
leaks may occur either during discharge or before. In one example of failure
before discharge,
a pressure sensor on one cylinder may indicate a leak (e.g., lower than
specified initial
pressure). In such a situation, the controller could be programmed to open
others of the
cylinders 24 in preference to that leaking cylinder. An example of in-use
failure involves a
failure of a device 30 to open or perhaps some blockage occurring. Such a
failure may be
specifically detected (e.g., by pressure sensors indicating pressure in the
cylinder is not
dropping as it should or possibly from flow sensors indicating a lack of
flow). Alternatively,
such failure could be inferred by a more generalized sensor determining
insufficiency of
flow. In either event, one or more additional cylinders may be brought online
and, optionally,
the initial group of cylinders may be taken off line. For any such leak or
failure, the controller
may maintain a log for display or downloading to/by a user.
[0055] The use of "first", "second", and the like in the description and
following claims is
for differentiation within the claim only and does not necessarily indicate
relative or absolute
importance or temporal order. Similarly, the identification in a claim of one
element as "first"
(or the like) does not preclude such "first" element from identifying an
element that is
referred to as "second" (or the like) in another claim or in the description.
[0056] Where a measure is given in English units followed by a
parenthetical containing
SI or other units, the parenthetical's units are a conversion and should not
imply a degree of
precision not found in the English units.
[0057] One or more embodiments have been described. Nevertheless, it
will be
understood that various modifications may be made. For example, when applied
to an
existing basic system, details of such configuration or its associated use may
influence details
of particular implementations. Accordingly, other embodiments are within the
scope of the
following claims.
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