U.S. patent number 3,830,307 [Application Number 05/325,539] was granted by the patent office on 1974-08-20 for fire prevention and/or suppression system.
This patent grant is currently assigned to Parker-Hannifin Corporation. Invention is credited to Kenneth R. Bragg, Richard A. Nichols.
United States Patent |
3,830,307 |
Bragg , et al. |
August 20, 1974 |
FIRE PREVENTION AND/OR SUPPRESSION SYSTEM
Abstract
A fire prevention and/or suppression system in which liquid
nitrogen is injected into a space to be protected against fire
and/or explosion. The nitrogen vaporizes in the space and mixes
with the combustible gases therein to extinguish flame that may be
present and/or render the gases non-flammable to prevent their
ignition, and also quickly cools the gases and/or other combustible
material that may be present to protect against ignition or
re-ignition.
Inventors: |
Bragg; Kenneth R. (Redondo
Beach, CA), Nichols; Richard A. (Santa Monica, CA) |
Assignee: |
Parker-Hannifin Corporation
(Cleveland, OH)
|
Family
ID: |
26712692 |
Appl.
No.: |
05/325,539 |
Filed: |
January 22, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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35994 |
May 11, 1970 |
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711020 |
Mar 6, 1968 |
3590559 |
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Current U.S.
Class: |
169/9;
169/11 |
Current CPC
Class: |
A62C
99/0009 (20130101); A62C 3/06 (20130101); A62C
3/08 (20130101); B64D 37/32 (20130101) |
Current International
Class: |
A62C
3/08 (20060101); A62C 39/00 (20060101); B64D
37/00 (20060101); B64D 37/32 (20060101); A62C
3/06 (20060101); A62C 3/00 (20060101); A62C
3/07 (20060101); A62c 001/24 () |
Field of
Search: |
;169/2R,5,9,11,30,31 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: King; Lloyd L.
Assistant Examiner: Mar; Michael Y.
Attorney, Agent or Firm: Wolfram; John N.
Parent Case Text
This application is a continuation of Ser. No. 35,994, filed May
11, 1970, now abandoned, which in turn is a continuation in part of
Ser. No. 711,020, filed Mar. 6, 1968, now Pat. No. 3,590,559.
Claims
We claim:
1. A system for preventing and/or extinguishing fire in a gaseous
space within a closed container, comprising a dewar containing a
cryogenic fluid, a portion of said fluid being in liquid form and
another portion being in gaseous form that exerts pressure on the
liquid, a conduit connecting the liquid containing portion of said
dewar to a fog nozzle communicating directly with said space, said
gaseous fluid providing the only source of pressure for moving said
liquid from the dewar through the conduit and the fog nozzle to
said space, said fog nozzle delivering said liquid to said space in
finely divided liquid droplets, a valve in said conduit controlling
flow of said cryogenic liquid from the dewar through said conduit
to said fog nozzle, means for detecting a fire in said space and
for opening said valve in response to said detection, and a one-way
vent valve for venting excess gas from the container to prevent
overpressurization of the container.
Description
SUMMARY OF THE INVENTION
In aircraft and other places where danger of fire or explosion
exists in particular locations because of the presence, or possible
presence of flammable materials, it is highly desirable to provide
means for preventing and/or extinguishing fire and to prevent
re-ignition if a fire has occurred and has been extinguished. In
the present system nitrogen, or some other cryogenic fluid, is
introduced into the space that is to be protected in liquid form,
and preferably in the form of fine liquid droplets. The droplets
vaporize in the space and mix with the oxygen gas in the space to
dilute, cool and or replace the same to the extent that there is
insufficient oxygen in the space to support combustion.
In addition, the liquid nitrogen, being very cold, such as in the
vicinity of -320.degree. F., exerts a very rapid and considerable
cooling effect on the oxygen and other gases in the space, and on
nongaseous materials in or adjacent to the space, to eliminate or
delay subsequent increase of temperature of the combustible
materials present to ignition levels.
DESCRIPTION
The drawing indicates a schematic view of a container having
cryogenic inert liquid therein connected by a conduit to a space to
be protected against fire or explosion.
The system may, for example, by an installation within an aircraft,
and as shown includes a dewar 10 containing liquid nitrogen 11. The
liquid nitrogen is under pressure due to vaporization of a portion
thereof, such vaporized nitrogen being in the upper portion of the
dewar. The pressure may be in the neighborhood of 30 to 70 psi, for
example, and is prevented from exceeding this pressure by a
pressure relief valve 12. The temperature of the liquid nitrogen
will be approximately -310.degree. F. to -290.degree. F.
The dewar is connected by a conduit 15 to the ullage space 16 of a
fuel tank 17 containing liquid fuel 18. The ullage space 16
contains fuel vapor and will also contain some oxygen that had
entered the tank either from the atmosphere or as dissolved gas in
the liquid fuel when the tank was being filled with fuel. The tank
ullage may also contain gaseous nitrogen previously introduced for
the purpose of rendering the oxygen-fuel vapor content of the
ullage non-flammable by keeping the oxygen content to about 11
percent or less of the total gaseous content of the ullage.
Mounted in conduit 15 is a normally closed control valve 21 having
associated therewith an operator 22, such as a solenoid, that may
be automatically actuated for opening valve 21 by a fire detection
means that includes fire detectors 23, 24, and a control unit 25.
Valve 21 also has associated therewith an operator 28 that may be
actuated by manual operation of a switch button 29 on control unit
25. Control unit 25 preferably includes a timer that operates to
shut off valve 21 after a predetermined period of time after being
opened by operator. A check valve 33 is also in the conduit and the
latter terminates at a fog nozzle 35 of conventional design for
spraying liquid nitrogen from conduit 15 into the tank ullage space
in small or finely divided liquid droplets. A one-way vent valve 38
permits venting of excess gas from the tank to prevent
overpressurizing of the tank interior.
Space 16 will contain fuel vapor and will also contain some oxygen,
as already explained. If the oxygen content becomes greater than
about 11 %, the fuel vapor-oxygen mixture will become flammable. If
ignition occurs, this will be detected by detectors 23, 24, which
may be of the infra-red type, and a signal will be generated for
causing control unit 25 to actuate operator 22 for opening valve
21. Liquid nitrogen will then flow from dewar 11 to nozzle 35 and
be sprayed therefrom in fine liquid droplet form into the tank
ullage where it will vaporize and quickly dilute the oxygen in the
ullage to the point where combustion ceases. Snuffing out of the
fire is also facilitated by the fact that the nitrogen also cools
the combustible gases. Furthermore, the nitrogen causes additional
cooling of the ullage contents and material adjacent thereto to
prevent or delay re-ignition after valve 21 has been shut off. Such
cooling occurs very rapidly with the use of liquid nitrogen as
described.
If valve 21 should fail to function when needed, or if it is
automatically shut off by the timer in control unit 25 before the
fire is extinguished, or if it is desired to introduce nitrogen
into the protected space as a precautionary measure, valve 21 may
be opened by manually depressing button 29. This manual operation
is of special importance if the space to be protected against fire
is within an engine nacelle, or surrounds a wheel brake, or is in
any other location where a dangerous condition may be
anticipated.
To assure that the nitrogen will reach nozzle 35 in liquid form,
conduit 15 may be of sufficient flow capacity (diameter) and of
short enough length so that the liquid will pass therethrough
before ambient temperature causes complete vaporization of the same
before it is discharged from nozzle 35. Some of the liquid nitrogen
may vaporize within the conduit before it reaches the nozzle
because the conduit, prior to initiation of flow therethrough, may
be at a temperature higher than that of the liquid nitrogen.
* * * * *