FIELD OF THE INVENTION
The present invention relates to a method of suppressing fire, more particularly a
method of suppressing fire in large buildings by diverting water from HV AC systems.
BACKGROUND OF THE INVENTION
Most buildings have water stored in large underground storage tanks for supplying
process water, tap water, water for fire-fighting etc. A limited amount of water is also
available in overhead tanks of comparatively lower capacity. In the event of fire,
water from "fire tanks", which are storage tanks dedicated to store water for
(; firefighting is used. Once this storage tank is exhausted, water from the other tanks is
transferred to the fire tanks because adequate water supply is essential for controlling
and extinguishing fire. These tanks can be refilled once the fire is extinguished.
Modern high rise buildings perform several functions like heating, ventilation, air
conditioning, etc. The three central functions of heating, ventilating, and airconditioning
are interrelated. Thus, in modern buildings the design, installation, and
control systems of these functions are integrated into one or more HV AC (Heating,
Ventilation, and Air Conditioning) systems. HV AC is the technology used to maintain
a comfortable environment inside industrial buildings, office buildings, vehicles, etc.
Integrating the various functions using an HV AC system increases the energy
efficiency of the building, facilitates usage of renewable energy sources and allows
integration of equipments of multiple buildings, thereby promoting design of
environment friendly buildings.
The air-conditioning system of an HV AC system can be categorized as an air-cooled
or water-cooled system depending upon the type of condenser used. The water-cooled
systems comprising a chilled-water system are extensively used because of their high
energy efficiency. In one type of system, a central chilled water plant consisting of
one or more chillers and their ancillary systems provides chilled water for air
conditioning. This chilled water is pumped to one or more air handling units (AHUs)
throughout the building, where heat from warm indoor air is transferred to the chilled
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water. The AHUs are usually connected to ducts that distribute the cooled/conditioned
air throughout the building. The chilled water that has taken up heat returns to the
chiller.
The chilled water plant requires several additional components (often called auxiliary
or ancillary systems) to move chilled water between the chilled-water plant and the
AHUs and reject heat from the chiller to the outside world. Auxiliary devices include
chilled water pumps, condenser water pumps, and cooling towers. Since water-cooled
systems are usually inside a building, heat from the chillers is carried by recirculating
water to outdoor cooling towers. The heat is released to the surroundings and the
cooled water is pumped back to the chiller.
Thus, large buildings have extensive air conditioning systems wherein several
thousand liters of water is available. In addition to that, the water is at a low
temperature, particularly in the pipelines provided between the AHUs and chillers.
Therefore, this chilled water can be very useful in case of a fire in a building. The
HV AC system has thousands of liters of chilled water in the various pipelines running
throughout the building. In several cases more water is in circulation in the HV AC
system than the water stored in the various storage tanks.
The storage tanks containing water for fire-fighting are usually designed to store only
enough water to keep the fire under control for a few minutes, until the fire trucks
arrive at the affected building. Thus, a situation may arise wherein the water stored in
the tanks is exhausted and the fire trucks have not arrived. This, problem is
particularly important in developing countries where water supply is often inadequate
and fire trucks are not available promptly. Thus, there is a need for means for
providing additional water to curb the spread of fire. The HVAC system has a
significant amount of chilled water as explained in the preceding paragraphs. It is an
object of the invention to use this chilled ofHV AC system for combating fire.
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SUMMARY OF THE INVENTION
In accordance with an embodiment of the invention, is provided a method of
suppressing fire in a building, wherein the building comprises an HV AC (Heating
Ventilation and Air Conditioning) system comprising:
- a plurality of Chillers, each chiller comprising a Condenser;
- a plurality of Air Handling Units I AHUs;
- a plurality of Cooling Towers;
- a plurality of pipelines/headers connecting the chillers with the AHUs; and,
- a plurality of pipelines/headers connecting the condensers with the cooling
towers;
the method comprising the steps of detecting a fire in the building and, diverting
water from the HV AC system.
In accordance with another embodiment of the invention, is provided a method of
suppressing fire in a building, wherein water from the HV AC system is diverted to a
plurality of fire tanks, from where it is supplied for suppressing fire.
In accordance with yet another embodiment of the invention, is provided a method of
suppressing fire in a building, wherein water is diverted from at least one of the
pipelines/headers of the HVAC system by connecting them to the plurality of fire
tanks with isolation valve(s).
In accordance with yet another embodiment of the invention, is provided a method of
suppressing fire in a building, wherein water is diverted from at least the chilled water
header by connecting it to the plurality of fire tanks with isolation valve(s).
In accordance with yet another embodiment of the invention, is provided a method of
suppressing fire in a building, wherein two pipelines along with one isolation valve
each are provided for connecting the chilled water header to the plurality of fire tanks.
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In accordance with yet another embodiment of the invention, is provided a method of
suppressing fire in a building, wherein water is diverted from at least the chilled water
return pipeline by connecting it to the plurality of fire tanks with isolation valve(s).
In accordance with yet another embodiment of the invention, is provided a method of
suppressing fire in a building, wherein the isolation valve(s) are operated manually or
automatically; the valves being opened when a fire is detected in the building and the
water level in the fire tank(s) is low.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic diagram showing a conventional air conditioning system of an
HV AC system for large buildings.
It is to be noted that the above mentioned figure is with reference to a water-cooled air
conditioning system wherein the chillers are provided inside the building and cooling
tower(s) is provided outside the building, preferably at the rooftop. However, the
teachings of the invention can be readily applied to other types of HVAC systems
also, with or without some minor modifications.
DESCRIPTION
Discussed below are some representative embodiments of the present invention. The
invention in its broader aspects is not limited to the specific details, representative
devices and methods, and illustrative examples shown and described in this section in
connection with the embodiments and methods. The invention according to its various
aspects is particularly pointed out and distinctly claimed in the appended claims read
in view of this specification, and appropriate equivalents.
It is to be noted that, as used in the specification and the appended claims, the singular
forms "a," "an," and "the" include plural referents unless the context clearly dictates
otherwise.
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Fig. 1 is a schematic diagram showing a conventional air conditioning system of an
HV AC system for large buildings. The central component is a chiller (1 00)
comprising a condenser ( 11 0) along with a compressor and evaporator (not shown in
figure). The chiller is connected to Air Handling Units I AHUs (120) provided at
several locations inside the building, and to a cooling tower (150) provided on the
rooftop of the building.
Water chilled to a temperature just a few degrees above the freezing point of water is
sent to the AHUs via pipelines L1 with the help of chilled water pumps (130). The
chilled water picks up heat from air and its temperature rises by a few degrees. The
water is returned to the chiller via pipelines L2 . During the chilling process, heat is
picked up at the condenser and transferred to the condenser water. The condenser
(; water is transferred to the cooling tower(s) via pipelines L3 for losing the heat. The
condenser water is cooled to approximately the ambient temperature at the cooling
tower(s) and returned to the condenser via pipelines L4 with the help of condenser
water pumps (140). In general, the water in pipelines L1 is the coldest while the water
in the pipelines L3 is the hottest. Several liters of water flows through each of the
pipelines L1. L2, L3 and L4• It is to be noted that L1. L2, etc. do not refer to signal
pipeline, but a group of pipelines provided between the process equipments.
In accordance with a preferred embodiment of the invention, the chilled water header
L1 is connected to the fire tanks with isolating valves. In accordance with another
preferred embodiment of the invention, the chilled water return pipeline L2 is
connected to the fire tanks with isolating valves. The isolating valves may be operated
manually or can be automatically opened when a fire is detected and the water level in
the fire tanks becomes low. Thus, when a fire is detected, using smoke detectors,
temperature sensors, visual inspection, etc., the isolating valves are opened to transfer
water from the HVAC system to the fire tanks.
In accordance with another embodiment of the invention, at least one of the pipelines
L1, L2, L3 and L4 is connected to the fire tanks with isolating valves. When two or
more pipelines are connected to the fire tanks, if the water in one of the pipelines is
exhausted, water from the other pipelines can still be utilized for fire fighting.
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In accordance with yet another embodiment of the invention is provided a method of
suppressing fire in a building, comprising the steps of:
a. connecting a chilled water header of the HV AC system to a plurality of fire
tanks with isolation valves;
b. detecting a fire in the building and the water level in the plurality of fire tanks;
c. opening the isolation valves to divert water from the chilled water header to
the fire tanks; and,
d. using water from the fire tanks for suppressing fire.
In another aspect, the invention provides a method of fire fighting by withdrawing
water directly from the chilled water header, without first transferring it to a fire tank.
Thus, in case of fire in the vicinity of the chilled water header, the water can be
directly released for suppressing the fire.
Several variations are possible within the scope of the invention. For instance, a
plurality of pipelines may be provided between the fire tanks and the
headers/pipelines (L1, L2, L3, L4, etc.). It is standard practice in industry to provide
pipelines, valves, pumps, etc in pairs so that even if one fails, the other can be used.
Thus, it would be preferred to provide two pipelines, each having an isolation valve,
connecting the fire tanks with the pipelines/headers. It is apparent that different types
and numbers of the valves, pipelines, chillers, pumps, etc. can be used for the
invention.
The invention is not limited to the embodiments which have been described and C illustrated by way of example and numerous modifications and variations would be
apparent to a person skilled in the art, without departing from the scope of the
appended claims.

We Claim:
1. A method of suppressing fire in a building, wherein the building comprises an
HVAC (Heating Ventilation and Air Conditioning) system comprising:
- a plurality of Chillers (100), each chiller comprising a Condenser (110);
- a plurality of Air Handling Units I AHUs (120);
- a plurality of Cooling Towers (150);
- a plurality of pipelines/headers connecting the chillers with the AHUs (L1 and
L2); and,
- a plurality of pipelines/headers connecting the condensers with the cooling
towers (L3 and L4);
the method comprising the steps of detecting a fire in the building and, diverting
water from the HVAC system.
2. The method of suppressing fire as claimed in claim 1, wherein water from the
HV AC system is diverted to a plurality of fire tanks, from where it is supplied
for suppressing fire.
3. The method of suppressing fire as claimed in any of the preceding claims,
wherein water is diverted from at least one ofthe pipelines/headers (L~, L2, L3,
L4, etc.) of the HV AC system by connecting them to the plurality of fire tanks
with isolation valve(s).
4. The method of suppressing fire as claimed in any of the claims 2 to 3, wherein
water is diverted from at least the chilled water header L1 by connecting it to
the plurality of fire tanks with isolation valve(s).
5. The method of suppressing fire as claimed in claim 4, wherein two pipelines
along with one isolation valve each are provided for connecting the chilled
water header L1 to the plurality of fire tanks.
6. The method of suppressing fire as claimed in any of the claims 2 to 5, wherein
water is diverted from at least the chilled water return pipeline L2 by
connecting it to the plurality of fire tanks with isolation valve(s).
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7. The method of suppressing fire as claimed in any of the claims 3 to 6, wherein
the isolation valve(s) are operated manually or automatically; the valves being
opened when a fire is detected in the building and the water level in the fire
tank(s) is low.
8. The method of suppressing fire as claimed in claim 1, wherein water from at
least one ofthe pipelines/headers (L1, L2, L3, L4, etc.) is directly released in the
vicinity of the pipelines/headers.