Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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COMPRESSED AIR FOAM SYSTEM FOR FIRE RETARDANCE
This invention relates to a compressed air foam generation system for
protecting a structure from fire and to a programable nozzle for use in the
system.
BACKGROUND OF THE INVENTION
For some time foaming agents have been used to increase the
effectiveness of water in the prevention and suppression of fires. Systems
have
traditionally used foaming agents, commonly known as surfactants, mixed in
holding
tanks or introduced into the water stream by a variety of methods. More
recently
systems have been developed which also provide for the injection of compressed
air
into the water/surfactant mixture to provide an improved quality and volume of
foam.
In US Patent No. 5,582,776 of the present inventors issued December
10th 1996 is disclosed a portable apparatus for generating foam. The apparatus
disclosed was particularly directed at an apparatus for making compressed air
foam
to be used in stationary or portable fire fighting systems and emergency
response
units. The system is particularly applicable to portable systems used in
forestry,
structure protection, rural and urban grass fires (Class A fires), and oil and
gas fires
(Class B fires).
In US Patent No. 6,733,004 of one of the present inventors issued May
11th 2004 is disclosed a portable apparatus for generating foam where there is
provided an improved valve arrangement for controlling the formation of the
foam.
The arrangement shown in the above patents was particularly
designed as a portable unit for use in remote locations.
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It is known that foam systems of this type can act to extinguish fires
and also as a fire retardant.
US Patent 6,522,616 (Wallace) issued February 25, 2003 discloses a
fire prevention system for a building which has foam nozzles outside the
building
and on the roof.
US Patent 7,104,334 (Thompson) issued September 12, 2006
discloses a portable remote actuable foam spray system which can be left in
place
when the persons depart and activated remotely. It shows in Figures 7 to 9 a
roof
mounted nozzle.
US Patent 5,165,482 (Smagac) issued November 24, 1992 discloses a
sprinkler system for protecting a building when a fire approaches. It does not
use
foam.
US Patent 6,450,264 (Christian) issued September 17, 2002 discloses
a roof mounted sprinkler system for forest fires. It does not use foam.
US Patent 5,125,458 (Berman) issued January 30, 1992 discloses a
sprinkler system for protecting a building when a fire approaches. It does not
use
foam.
SUMMARY OF THE INVENTION
It is one object of the present invention to provide an improved
apparatus for fire retardance.
According to a first aspect of the invention there is provided an
apparatus for protecting a structure from fire comprising:
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a source of compressed air under pressure;
a pump for pumping water to be foamed having a pump inlet for
connection to a water supply and a pump outlet;
a source of a foaming agent;
a mixing system for mixing the water, the compressed air and the
foaming agent to generate a fire retardant foam;
a plurality of separate nozzles each arranged for spraying the foam;
each nozzle having a motor arrangement to move the nozzle to
different directions for spraying a pattern;
and a control device which is programmable to provide a program of
operation to control the meter or motors of the nozzles;
the control device being programmed with at least one pre-determined
program arranged to control each of the nozzles independently to provide for
each
nozzle a pre-determined pattern where the pattern of at least one nozzle is
different
from the pattern of one or more of the other nozzles;
the control device being arranged so that the different patterns of the
nozzles combine to form a pre-determined pattern of a layer of the fire
retardant
foam on the structure to cover the structure with the layer to protect the
structure
from fire.
Preferably there is provided a remote control for communication with
the control device for remote actuation.
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Preferably the control device includes a plurality of predetermined
programs of operation of the nozzles; where the predetermined programs are
arranged to provide different ones of a plurality of predetermined patterns of
the fire
retardant foam on the structure.
Preferably the control device is programmed with said at least one pre-
determined program arranged to operate the nozzles periodically with the time
period between operations being programable.
Preferably there is provided a remote control for communication with
the control device and wherein the remote control is arranged to select one of
a
plurality of programs of operation of the control device.
Preferably the control device is programmed with said at least one pre-
determined program which is arranged so that the nozzles cooperate to cover a
surface by the foam.
Preferably there is provided a sensor for detecting a heat intensity
indicative of an intensity of a fire on the structure and wherein the control
device is
programmed in response to a signal from the sensor to cycle from one nozzle to
another at two or more rates depending on the intensity of the fire.
Preferably there is provided a heat seeking sensor for detecting a
location within the structure which has a temperature indicative of combustion
occurring at the location and wherein the control device is responsive to said
heat
seeking sensor to control said motor of said at least one nozzle to apply said
foam to
said location when detected.
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Preferably each nozzle is arranged reach to 80 feet at a 45 angle.
Preferably the control device is programmed in a subsequent step to
use plain water with the nozzles to wash the sprayed foam away.
Preferably there is provided an internal combustion engine for driving
5 the pump and a compressor for the compressed air.
Preferably there is provided a processor for controlling [the] starting
and operation of the internal combustion engine, for controlling the
compressor and
for controlling the pump in response to outputs from sensors such that foam is
available to be supplied solely upon supply of an actuation signal from the
control
device.
Preferably the processor is arranged to be responsive to a first sensor
to check for a predetermined minimum rpm to indicate starting of the engine.
Preferably the processor is arranged to be responsive to said first
sensor indicating said predetermined minimum rpm to operate the airflow valve
to
enable the air compressor.
Preferably the processor is arranged to be responsive to a second
sensor to detect the presence of air pressure generated by the compressor to
actuate ramp up of engine rpm from an idle speed to an operating speed.
Preferably there is provided a pump priming system operable to
release any existing air in the pump and wherein the processor is responsive
to the
absence of pump flow detected by a third sensor to actuate the pump priming
system.
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Preferably there is provided a pressure balance valve for controlling
the supply of air and water and wherein the processor is responsive to the
detection
of water flow by the third sensor to actuate the pressure balance valve.
The system can be programmed in several ways.
1. Cycled nozzles where there are several nozzles each nozzle
would be programmed to apply a specific pattern. The system could be
programmed to cycle from one nozzle to another at two or more rates depending
on
the intensity of the fire.(Protection or Fire fighting.)
2. Single nozzle where there is a smaller exposure a single nozzle
could be programmed to apply foam at a specific frequency or continuously.
3. Fire seeking where a heat seeking sensor can be added to
apply foam to a specific heat source either as a primary program or as an over-
ride
to a cycling program as indicated in 1 or 2.
The device combines advanced technologies to provide the best
available automatic fire defence.
The device has a nozzle which uses only 40-60 gallons per minute of
water to apply fire protection foam. This is the same or better than 1200
gallons per
minute of water being sprayed upon a building continuously.
The device has a nozzle which reaches up to 80 feet (30 meters) at a
450 angle.
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The device has a nozzle which does not need to spray continuously;
since the foam blanket can last up to 40 minutes, depending upon conditions.
The device is easy to install into either existing building or new
construction.
The device is a self-contained system; it does not depend upon outside
electricity or water.
The device is easy to use, turn on the switch or even better use the
remote control after you leave.
The device uses environmentally friendly foam which is easy to clean
and the device can be programmed to automatically wash the foam away once the
danger has passed.
BRIEF DESCRIPTION OF THE DRAWINGS
One embodiment of the invention will now be described in conjunction
with the accompanying drawings in which:
Figure 1 is a schematic illustration of the system according to the
present invention.
Figure 2 is a schematic layout of the foam generation system of Figure
1.
Figure 3 is an enlarged view of one of the nozzles of Figure 1.
In the drawings like characters of reference indicate corresponding
parts in the different figures.
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DETAILED DESCRIPTION
As shown in Figure 1 there is provided an apparatus 100 for protecting
a structure 101 from fire. Many such structures can be protected including
primarily
single family homes but also many other buildings which may be in the path of
wild
fires or other areas prone to fire. The intention is that the system be used
to protect
the exterior of the building from a passing fire. However the same system can
be
used in the interior of the building where a limited number of nozzles can be
used to
cover a sufficient part of the interior to protect against a fire starting in
the interior.
In addition to homes, the system can be used to protect other
structures such as remote antennas, pumping stations, shelters and any other
structure of sufficient value to require protection.
The apparatus includes a water supply 11 which in the embodiment
shown is a dedicated water tank but can be any permanent supply of water such
as
a lagoon or swimming pool.
A foam generation system 102 shown in more detail in Figure 2
includes a source of compressed air under pressure. This can be a compressor
10A
or can be a tank of compressed air (not shown). A pump 16 for pumping water to
be
foamed has a pump inlet for connection to the water supply 11 and a pump
outlet
17. A source of a foaming agent in the form of one or more tanks 12A and 12B
supplies a surfactant of known characteristics to a mixing system 15 for
mixing the
water, the compressed air and the foaming agent to generate a fire retardant
foam.
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In the preferred embodiment the compressor and pump are driven by a
dedicated internal combustion engine 40 with all of the components of the foam
generation system being mounted in a protective housing 103. The housing is
located adjacent the building so as to fall within the protective zone defined
by the
foam.
The apparatus includes at least one and preferably a series of nozzle
assemblies 104 for spraying the foam arranged at positions around the
structure to
be protected and arranged to apply a coating of foam over the whole structure.
Each nozzle assembly 104 has a jet nozzle 105 and a motor arrangement 106 to
move the nozzle to different directions for spraying a pattern over the
structure. The
motor arrangement includes a first motor 107 and a second motor 112 arranged
to
rotate the nozzle about two orthogonal axes which are preferably horizontal
and
vertical.
The apparatus includes a control system 108 which can be actuated by
a remote actuation device 109 or by a local switch 110 to actuate and control
the
individual nozzles 104 in accordance with set programs. The system 108
communicates with a respective control device which 111 of each nozzle which
is
programable to provide a program of operation to control the motor or motors
so as
to pre-determine the pattern.
The control devices can be programed either at the central control unit
108 or at the individual units 111 to drive movement of the nozzles to combine
to
cover a structure to be protected. Thus each nozzle is scanned vertically and
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horizontally to "paint" an area of the structure with the foam as a layer.
Thus the
amount of vertical movement, preferably in stepped positions, and the amount
of
horizontal movement at each vertical position is controlled to match the shape
to be
covered.
5 Thus each nozzle can be programmed to apply a specific pattern
different from one or more of the other nozzles depending on the shape of the
structure and the locations of the nozzles relative to that structure. It will
be
appreciated that the initial programming of the nozzles is set up so as to
ensure that
the structure is fully covered using preferably a minimum number of nozzles
with the
10 nozzles being located and programed for best efficiency and adequate
coverage.
After the initial installation, subsidiary programming can be provided to
allow periodic operation of the system to ensure an adequate coating of foam
is
maintained to accommodate different levels of risk, depending on the situation
surrounding the structure.
The remote actuation device 109 is arranged to select from a plurality
of predetermined programs 113 of operation of the nozzle or nozzles. These
programs particularly relate to the operation of the nozzles periodically with
the time
between operations being programable and the time period of operation being
controllable.
The control device can be programmed to cycle from one nozzle to
another at two or more rates depending on the intensity of the fire.
Alternatively all
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nozzles may be operated simultaneously and controlled periodically or
continually
depending on required foam coverage.
In addition there may be there is provided a heat seeking sensor 115,
such as an infra red detector, which detects local hot spots and acts to
control one
or more nozzles to apply foam to a specific heat location when detected.
The/or each nozzle typically uses only 40-60 gallons per minute of
water to apply fire protection foam. The/or each nozzle is arranged reach up
to 80
feet (30 meters) at a 450 angle. A coating can remain effective for up to 40
minutes.
Using these parameters, the installer can select suitable location and
programming
of the nozzles and suitable supply of water to maintain the required coverage.
The apparatus is arranged as a self-contained system so that it does
not depend upon outside electricity or water.
As a further programming of the control system, it can be programmed
to use plain water with the nozzles to wash the foam away when the danger has
fully
passed.
Turning now to Figure 2, further detail of the foam generation system
are shown. This includes a compressed air supply 10, the water supply 11, the
foaming agent supply 12 and a foam discharge system 13 supplying the foam to
the
nozzles 104.
The compressed air supply 10 includes a compressor 10A, an inlet
control valve 10B to the compressor and a sensor 10C for detecting the
presence of
pressure at the outlet of the compressor.
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The system further includes a control valve 14 which controls the
supply of the compressed air from the compressed air supply 10 to a mixer 15
which
is of the construction shown in the above patent.
The water from the water supply 11 is supplied to a pump 16 which
generates water flow in an output line 17. Downstream of the pump is a sensor
16A
for detecting presence of water pressure. A priming system 16B is located at
the
pump inlet which extracts any air from the pump inlet when activated. Priming
devices for this purpose are available of different types, for example venturi
activated devices which generate a suction to extract any air from the inlet.
The
water passes through a back check valve 18.
The pump 16 and the compressor 10A are driven by an engine 40
which is preferably a diesel engine. The engine 40 includes a throttle control
41, a
starter motor 42, and an engine rpm sensor 43.
A processor or PLC control system 50 takes inputs from the sensors
1OC, 16A and 43 and from an input start button 51 and controls the valve 10B,
the
throttle control 41, the primer 16B, and the starter motor 42.
An injector 19 of the type shown in the above patent adds to the water
in the line 17 an amount of foaming agent proportional to the water flow. Thus
the
injector 19 is responsive to the water flow and adds the quantity of foaming
agent
necessary to match that water flow at the required ratio which is constant for
all
water flow rates. The supply 12 of foaming agent includes a first supply 12A
and a
second supply 12B for different types of foaming agent.
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The flow rate within the duct 17 is controlled by a valve generally
indicated at 20. The valve comprises a ball valve 21 which has a ball
schematically
indicated at 22 with an orifice 23 so that rotation of the ball varies the
amount of the
orifice accessible to the line 17 from 0 up to 100% thus continuously variably
adjusting the flow rate from fully off to fully on. The ball is rotated
through 900 by a
motor 25 controlled by an electronic control system 26. A commercially
available
valve, motor and control unit is available and is suitable for use in an
arrangement of
this type.
The motor is thus a motor which drives the ball valve from fully closed
to fully open through a series of pre-selected steps of the motor. A suitable
commercially available device uses a potentiometer feed-back system which
allows
specific points on the potentiometer to be selected and the motor operated to
move
to those pre-selected positions of the potentiometer. The electronic
controller 26
includes a display 27, setting switches 28 and 29 and a single operating
switch 30.
In operation, the system is actuated by the switch 110 or by the remote
109 which acts to provide a start signal and the processor 50 controls the
operation
of the unit to generate foam as follows:
Step Description
1. Engage start switch 51
2. Time delay-glow plugs heat. The diesel engine includes
conventional glow plugs which generate heat to allow the engine to start. The
time
delay is determined by the processor to allow sufficient heating to occur.
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3. Starter motor 42 is engaged by the processor 50.
4. Starter motor is activated by the processor 50 runs for a
preset time.
5. Check by the processor 50 of the sensor 43 for a
minimum RPM indicative of start up.
6. If no start is detected, the processor returns to Step 1.
7. If a minimum RPM is detected indicative of start up of the
engine, the processor 50 activates the air compressor 1 OA by opening the
inlet valve
10B.
8. If pressure is detected by the sensor 10C, this is
communicated to the processor which acts to activate the throttle control 41
to ramp
up engine speed as the pressure increases.
9. The sensor 16A is sensed by the processor 41 to check
for water pressure.
10. If no water pressure is sensed, the processor engages
the air primer 16B.
11. The sensor 16A is sensed by the processor 41 to check
for water pressure.
12. If water pressure is sensed, the processor disengages
the air primer.
13. At the same time the processor acts to engage the
pressure balance valve 25.
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14. Unit is now read to make foam
15A. Open One touch valve
Air solenoid opens to One Touch line
15B. Select foam on foam/gel switch
5 Air solenoid opens to Foam/gel line
Foam/gel valve switches to foam
15C. Select gel on foam/gel switch
Foam/gel valve switches to gel
15D. Turn manual foam switch ON
10 Air solenoid to manual valve opens
The flow rate of water and foaming agent necessary to generate
certain characteristics of foam is previously determined. Thus three different
characteristics of foam can be formed of dry, wet and extra wet as described
in the
above patent.
15 The control unit is therefore operated to select positions of the
operation of the motor determined to provide the above three flow rates as
measured at the output 13 in the absence of compressed air so that the volume
of
liquid flowing is accurately determined and adjusted by the set switches 28
and 29.
With the controller so set, the controller is arranged such that each
operation of the operating switch 30 cycles the system through each of the
five
conditions in turn that is fully closed, dry, wet, super wet and fully open in
turn with a
further actuation of the switch returning the system to the fully closed
position.
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Thus with the system set to cycle in this manner and with the set
positions selected at the locations of the motor so as to provide the
accurately
measured required flow rate, the compressed air supply is activated and the
control
switch 30 operated to supply the required quantity of water.
The control unit is further arranged so that when the control switch is
operated to the fully closed position, the compressed air supply is also
deactivated
so that the system is off.
The control unit is also arranged so that when the cycling switch 30
moves the control of the pump to the fully opened position, the compressed air
supply is also switched off. At the same time the foaming agent from the
supply 1
which is used with the compressed air foam is replaced with other foaming
agents
on supply 2 which can be used for foaming only water so that when the water
supply
is on full, no compressed air is added and the foaming agent from the supply 2
acts
in the mixer to generate the required foam. In some cases, depending upon the
type
of foaming agent used, and many are available, the same foaming agent may be
used for both functions with the amount being increased approximately three-
fold for
the non-compressed air foam.
In Figure 2 is shown an alternative control unit 41 which includes a
single pole two position on-off switch 40 and five momentary switches 42 each
of
which provides a pre-set for the conditions previously stated. Each switch 42
is
associated with a respective LED 43 which is illuminated to indicate to the
user the
condition which has been selected by depression of the switch concerned.
