U.S. patent number 3,735,376 [Application Number 05/121,452] was granted by the patent office on 1973-05-22 for leakage indicator for a fire extinguisher.
This patent grant is currently assigned to HTL Industries, Inc.. Invention is credited to Jack M. Kermer, Abdul N. Sitabkhan.
United States Patent |
3,735,376 |
Kermer , et al. |
May 22, 1973 |
LEAKAGE INDICATOR FOR A FIRE EXTINGUISHER
Abstract
A temperature compensated alarm mechanism for a fire
extinguisher suitable for use on aircraft or other vehicles for
determining whether the pressure of the fire extinguishing fluids
within the main container has dropped below a predetermined value
due to leakage or to other conditions. The mechanism includes, in
addition to the main container, a miniaturized container which may
be inserted into the main container and is filled with like fluids
and arranged so that a diaphragm effectively separates the fluids
of the two containers from each other. The diaphragm may be
actuated in response to a predetermined droppage of the pressure of
the main container to produce a signal indicating that the fire
extinguisher may have been rendered incapable of responding with
sufficient force to a condition requiring prompt attention for
extinguishing or suppressing a fire. The mechanism is substantially
non-responsive to wide variations in the temperature of the media
external to the fire extinguisher.
Inventors: |
Kermer; Jack M. (Los Angeles,
CA), Sitabkhan; Abdul N. (El Monte, CA) |
Assignee: |
HTL Industries, Inc. (Monrovia,
CA)
|
Family
ID: |
22396831 |
Appl.
No.: |
05/121,452 |
Filed: |
March 5, 1971 |
Current U.S.
Class: |
340/605; 169/23;
200/83R; 340/626 |
Current CPC
Class: |
A62C
37/50 (20130101) |
Current International
Class: |
A62C
37/50 (20060101); A62C 37/00 (20060101); A62c
039/02 (); H01h 035/34 () |
Field of
Search: |
;200/81,83 ;340/240,242
;169/23,28 ;116/70 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Caldwell; John W.
Assistant Examiner: Partridge; Scott F.
Claims
What is claimed is:
1. The combination of a fire extinguisher having a first container
filled with fire extinguishing fluid, a second container filled
with fluid of substantially the same composition and proportion of
fire extinguishing fluid as in the first container, a protective
housing having a diaphragm for coupling the two containers to each
other, said diaphragm sealing the second container so that one side
of the diaphragm is subjected to the pressure of the fluid of the
second container, the other side of said diaphragm being exposed to
the pressure of the fluid of the first container, and means
responsive to a predetermined differential pressure between the
fluids of the two containers to render a signal substantially
independently of the ambient temperature.
2. The combination recited in claim 1 in which the diaphragm is
made of flexible material and the fluid is freon and nitrogen.
3. The combination recited in claim 1 in which the diaphragm is
made of corrugated stainless steel.
4. The combination recited in claim 1 including a signal circuit
responsive to the rendered signal.
5. A temperature compensated detecting apparatus for a fire
extinguisher having a container filled with fire extinguishing
fluid, comprising a second container mounted within the first
container and filled with substantially the same fire extinguishing
fluid as the first container, a flexible diaphragm for sealing the
second container, one side of the diaphragm being exposed to the
fluid in the second container, said diaphragm preventing the flow
of fluid from either container to the other, the other side of said
diaphragm being exposed to the fluid in the first container, and
apparatus responsive to the flexure of said diaphragm by a
predetermined amount to produce a signal independently of the
ambient temperature.
6. A temperature compensating detector apparatus for a fire
extinguisher according to claim 5, in which the diaphragm between
the two containers is made of corrugated stainless steel so as to
be flexible and continuously responsive to changes in fluid
pressure.
7. Apparatus for a fire extinguisher for detecting leakage of freon
and nitrogen from a container of the fire extinguisher, comprising
means for responding to a droppage in the pressure of the freon and
nitrogen of said container and non-responsive to variations in the
temperature of external ambient conditions, said means including a
second container filled with substantially the same proportion of
freon and nitrogen and positioned closely adjacent to the first
container and sealed by a flexible diaphragm so that one side of
said diaphragm is exposed only to the fluid of the first container
and the other side of said diaphragm is exposed only to the fluid
of the second container, and a signalling circuit responding to the
flexure of said diaphragm to indicate that the pressure on the side
of said diaphragm exposed to the fluid of the first container has
substantially departed from a predetermined level.
8. Apparatus according to claim 7 in which the diaphragm is
composed of corrugated stainless steel and responds promptly to
pressure variations.
9. Apparatus according to claim 7 in which the signalling circuit
includes a switch which is mechanically coupled to the
diaphragm.
10. Apparatus for detecting leakage of freon liquid and nitrogen
gas from a fire extinguisher container independently of ambient
conditions, comprising a miniature container filled with the same
proportion of freon liquid and nitrogen gas, a housing sealed to
the fire extinguisher container and coupling the two containers to
each other so that the miniature container is cantilevered from the
interior of the fire extinguisher container, the housing including
a diaphragm one side of which hermetically seals the miniature
container, the housing including an opening so arranged that the
other side of the diaphragm receives and is exposed to the fluid in
the fire extinguisher container, a switch member mechanically
coupled to a central portion of the surface of said diaphragm, said
signalling means controlled by said switch.
11. Apparatus according to claim 10 in which the signalling means
includes a remotely controlled indicator.
12. A temperature compensated detecting apparatus for a fire
extinguisher having a first container filled with fire
extinguishing freon liquid and nitrogen gas comprising:
a mounting plate adapted to be mounted in the first container;
a second container mounted within the mounting plate and
cantilevered into the interior of the first container and filled
with the same fire extinguishing proportion of freon liquid and
nitrogen gas as the first container;
a flexible corrugated, steel diaphragm for sealing the second
container, one side of the diaphragm being exposed to the liquid
and gas in the second container, said diaphragm preventing the flow
of liquid or gas from either container to the other, the other side
of said diaphragm being exposed to the liquid and gas in the first
container, and means responsive to the flexure of said diaphragm by
a predetermined amount for producing a signal independently of the
ambient temperature between a temperature range of -65.degree. F
and +300.degree. F.
13. Apparatus according to claim 12 including a switch positioned
adjacent the diaphragm and responding continually to the deflection
of the diaphragm, and a circuit controlled by the switch to
generate the signal.
Description
It has been noted that a conventional fire extinguisher for use on
aircraft or other vehicles, which is or may be, for example, a
high-pressure type employing a pressure of say 600psi, can be
subjected to losses of pressure due to leakages of the fluids in
its container. Such leakages may occur due, for example, to
accidental droppage of the container by a maintenance man or for
numerous other reasons. Such a container may be rendered useless if
its fire extinguishing fluid leaks appreciably. A hazardous
condition naturally develops on account of such leakage and this
would be a source of great concern to the staff in charge of the
plane's operation and naturally also a matter of real danger to the
passengers or the cargo on the craft.
Other sources of leakage from a container of a fire extinguisher
may be due to microscopic openings in the metal of which the
container is made, flaws in the welding material which are not
readily detectable, fatigue of the material of the container
because of its stresses and strains, etc., etc. Any or all of these
factors may be coexistent and may materially affect adversely the
operativeness and utility of the fire extinguisher as a servicing
element for its primary and essential functions.
It has been customary in certain types of aircraft to connect the
container of a fire extinguisher by means of a conduit to a
so-called "discharge indicator" located on the "skin" of the
aircraft so that, if the container has discharged all or a good
deal of its fire extinguisher fluids through the conduit due to an
abnormal condition due to temperature, the disc of this indicator
would become severed or removed. Such a condition would be readily
detectable to personnel but the detection is made on the ground
after the aircraft has landed. An inspector at an airport might
then alert the maintenance people of the inoperativeness of the
fire extinguisher. The condition may be overcome by replacement or
repair of the fire extinguishing equipment. But, as noted, this
temperature condition is customarily detected only for abnormal
temperature conditions. A leakage condition is not detectable by
this means and hence leaves the fire extinguisher in an inoperative
condition, the inoperative condition remaining unnoticeable and
undetectable by the inspector.
In order to overcome some of the principal defects affecting the
operation of a fire extinguisher, a temperature-compensated
pressure switch mechanism has been developed. The pressure switch
mechanism according to this invention includes, in addition to the
main container of the fire extinguisher, a second container of a
miniaturized size containing the same types of fluids as the main
container, together with a flexible diaphragm and a microswitch, so
arranged and coordinated that the diaphragm is positioned
substantially at an opening or port or ports separating the two
containers, so that the fluid in one of the containers will act
against one side of the diaphragm while the fluid within the other
container will act upon the other side of the same diaphragm.
Hence, whenever the pressures of the fluids on the two sides are
materially different, the micro-switch mechanism will be actuated
and signal the cabin officer, for example, or others that an
incipient adverse condition has developed within the main container
of the fire extinguisher that requires prompt attention.
One of the primary objects of this invention is to provide a fire
extinguishing container together with a miniaturized container
containing the same chemical or fluidic components as the main
container and subjected substantially to the same conditions of
pressure and temperature, so that when a predetermined pressure
differential develops between the fluids of the two containers,
whether due to internal pressure or other factors, the condition
will be promptly relayed to a central point or a remote point or to
the cabin of an aircraft advising that a hazardous condition has
developed within the fire extinguishing mechanism.
Another of the objects of this invention is to provide a relatively
small chamber common to the two coupled containers so arranged that
the chamber has a flexible diaphragm therein separating the fluids
of the two chambers. In this arrangement, the diaphragm will
respond to a sufficient pressure differential between the fluid
components of the two containers and the diaphragm will actuate a
switch to light a lamp or provide a signal which can be easily and
promptly detectable. Such an arrangement can serve to inform the
staff of an aircraft that a menacing condition has developed
whereupon the staff may signal the nearest landing field that the
fire extinguisher may need prompt replacement or repair.
This invention, together with its objects and features, will be
better and more clearly understood from the following description
and explanation hereinafter given when read in connection with the
accompanying drawing in which
FIG. 1 schematically illustrates a segment of a fire extinguisher
to show one form of the invention, the segment of the container
apparatus of the fire extinguisher being shown in cross-section,
and
FIG. 2 schematically illustrates a more complete fire extinguisher
showing other valves of such an extinguisher in their relative
positions.
Referring to FIGS. 1 and 2 of the drawing, two containers TA and TB
are shown, container TA constituting the main container and
container TB constituting a miniature container coupled, as will be
explained, to the main container TA. The container TA is the
container of a conventional fire extinguisher which may, for
example, embody an elliptical or spherical or cylindrical metal
housing and may be 12 or 15 or more inches in diameter and of any
length and may contain a quantity of fire extinguishing fluid, such
as freon 1301, and a quantity of nitrogen gas as a pressurizing
fluid, while the second container TB may be, for example, a
miniaturized container preferably cylindrical in shape, and having
a much smaller diameter, for example, a diameter of about one-half
inch, but filled with identical or substantially identical fluid
components, namely freon 1301 and nitrogen gas, in the same general
proportions. Both containers, TA and TB, may be pressurized to
substantially similar or equal pressures in the range of, for
example, 600 psi. If the fluid within container TA has a pressure
of let's say 600 psi at normal temperature, the container TB may
preferably be pressurized to a somewhat lower fluid pressure, about
580 psi, or slightly below the indicated pressure at the same
temperature of the container TA. Thus, there are two containers of
the same fluidic compounds and both subjected to the same
parameters of the pressurized fire extinguishing fluids, both
separately encased and welded or brazed in the respective
containers so as to be hermetically sealed to maintain the fluids
of the two containers separate and distinct from each other at all
times.
Container TB, the miniaturized container, may be provided with a
cap CP which may be made of two parts CP1 and CP2, both made of
stainless steel, for example, which may be welded or brazed to each
other and to the upper periphery of the miniature container TB as
shown in the drawing. The principal container TA may be provided
with an external housing structure SW located on the upper side of
container TA and welded or brazed to container TA as shown and to
cap segment CP1. A diaphragm DF is positioned in a cylindrical
opening or cavity within the cap segment CP2 as shown. Cap segment
CP2 is provided with a central port PT0 so that the fire
extinguishing fluid in the miniature container TB may provide its
own pressure on the underside of diaphragm DF.
The diaphragm DF may preferably be any flexible diaphragm readily
responding to miniature pressure differentials of the fluids of
both containers. It has a projection or projections which rest
against the lower side of the cylindrical opening or cavity in the
cap segment CP2, as shown. The additional housing structure is
arranged so that it may be fitted into an appropriate opening in
the outer wall of the larger container TA. The cap segment CP2 has
two or more ports PT1 and PT2 which freely allow the fluid of the
first container TA to enter therethrough and continually provide
pressure against the upper side of the diaphragm DF. Hence, the
diaphragm DF will be subjected to the upward pressure through a
port PT0 in cap segment CP2 due to the fluid of container TB on the
lower side of diaphragm DF and also the downward pressure of the
fluid of the larger container TA admitted through ports PT1 and PT2
and acting against the upper side of diaphragm DF.
It will be noted that a floating actuator AK, smaller in diameter
than the diaphragm DF, is rested or seated on the diaphragm DF, as
shown. The floating actuator AK has a centrally positioned button
BT on its upper side which is located adjacent to a microswitch
button MSB of a microswitch MS. The microswitch button MSB is
connectable to complete and operate an electrical circuit W1, W2,
which may be powered by any source of voltage B, such as a battery
or any common DC or AC source. The electrical circuit W1, W2 may
include a visual indicator, such as a lamp LP, or an audible
indicator (not shown), or both, and the circuit may be wired and
ordinarily would be wired to the cockpit or to an attendant's
position to signal a hazardous condition should it develop.
When the pressure on the lower side of the diaphragm DF exceeds the
pressure on the upper side of the diaphragm DF by a significant and
predetermined differential pressure, diaphragm DF will be raised to
cause the floating actuator AK to move its projecting button BT to
strike and move the microswitch button MSB, thereby closing the
circuit W1, W2 to the lamp LP to illuminate the lamp LP and thereby
signal the various personnel.
Both containers TA and TB may be subjected to normal variations in
pressure due to normal variations in the ambient temperature or
other external conditions. Thus, if the ambient temperature should
drop, for example, to minus 65.degree.F, this temperature being in
the normal range, the pressure in the container TA may drop
correspondingly to say 180 psi, while the pressure in the second
container TB may also drop to say 170 psi. In that event, the
diaphragm DF will remain undeflected and the microswitch MS will
remain unactuated. The lamp LP will indicate no significant change
in the condition of the principal container TA. The fire
extinguisher and its container TA would be expected to operate
satisfactorily. External temperature variations and corresponding
external pressure variations will thus be substantially
non-effective in operating the signal circuit to illuminate lamp
LP.
For calibration and testing purposes, assume, for example, that the
miniature container TB is disassociated from the container TA, but
that the diaphragm DF and its associated mechanism remains
connected to the microswitch MS, as shown in the drawing. In this
condition, the only force acting on the sealed diaphragm DF will be
that arising from the pressure of the fluid of container TB.
Inasmuch as the force acting on the diaphragm DF is in an upward
direction due to the pressurized medium in the container TB, then
the microswitch MS will be actuated by the flexure of the diaphragm
DF and the condition will be indicated by the operation of the lamp
LP. Now consider that the ports PT1 and PT2 are then connected to a
variable pressure source of fluid, that the source delivers its
fluid under pressure and that the pressure is raised from a low
level to an increasing value. While the pressure of the fluid
admitted through ports PT1 and PT2 is initially low relatively, the
microswitch MS will remain closed and the lamp LP will continue to
remain lighted. As the pressure supplied through ports PT1 and PT2
is raised further, the previous condition will be continued until a
level of fluid pressure, a predetermined pressure, is reached
through the ports PT1 and PT2. This pressure will return the
diaphragm DF to its former lower or initial position. In that case,
the microswitch MS will be released, extinguishing the lamp LP.
We can now determine and establish the value of the predetermined
fluid pressure delivered through ports PT1 and PT2 which will
return the diaphragm DF to its initial or normal released position.
This pressure may be and should be somewhat different from the
prevailing pressure in the main container TA. This differential
pressure will be significant in the general operation of the
overall mechanism.
Now assume that the larger container TA is filled with its fire
extinguishing fluid or fluids, as already described, and that the
fluid pressure is brought to a value approximately equal to the
value that previously returned the diaphragm DF to its released or
normal position. That internal pressure within container TA will be
a normal value and within the normal operating pressure range of
container TA, and such a pressure will keep the container TA in
good condition. Now assume that the container TA is supplied with a
conventional relief valve (not shown) which permits some of the
fluid contents of the container TA to be released whenever desired.
This relief valve may be employed to reduce the internal pressure
within the container TA so that we can bring about an operative
condition by opening the relief valve, that is, a condition in
which the diaphragm DF will be actuated again because the pressure
on its upper side is at a lower value than the pressure on the
lower side of the diaphragm. Now if the relief valve were closed or
sealed so as to maintain the pressure within the container TA at
its earlier normal level, the arrangement would function so that,
if the ambient temperature should vary between, for example, minus
65.degree.F and plus 300.degree.F, the fluid pressure resulting
from any change in temperature over that entire range would
maintain the diaphragm DF in its released or normal position and
the lamp LP would remain extinguished. Thus, temperature changes
within this normal or ambient range will be non-effective in
operating the signal circuit W1, W2.
If now we open the relief valve to release an appreciable amount of
the fluid within the main container TA, the pressure within the
container TA will be considerably lower than previously, thereby
causing the diaphragm DF to be moved upwardly to operate the
microswitch MS, and thereby operate circuit W1, W2 and illuminate
the lamp LP. This operation of the diaphragm DF to its upward or
operating position in response to the lowering of pressure in
container TA and the consequent lighting of the lamp LP will be
maintained and continued regardless of any variation in the ambient
temperature. In other words, the signal mechanism will be operated
independently of variations in ambient temperature, whether the
circuit is in its operated or released condition. This is an
important fail-safe feature of the equipment. The lamp LP or other
indicator or indicators may be located at remote points, such as
the cockpit, etc.
Thus, the switching arrangement and the controlled signal circuit
W1, W2 remain in their released condition if the fluid in container
TA is held at a normal range of internal pressures substantially
free of leakage. Moreover, the switching arrangement and the
controlled signal circuit will be in their operated condition, and
remain in their operated condition if they were previously
operated, in response to leakage of fluid from container TA. As
observed, these conditions are substantially free from
environmental changes in the ambient temperature over a range of,
for example, minus 65.degree.F to plus 300.degree.F. Furthermore,
the switching arrangement and the controlled signal circuit will
remain unchanged and unaffected even if the ambient temperature
varies considerably beyond the above designated normal temperature
range. In other words, this mechanism responds solely to
differential pressures of sufficient magnitude between the fluids
in the two containers TA and TB and is non-responsive to ambient
temperature variations.
The equipment of this invention is capable of monitoring
continuously and promptly any substantial deviation in the pressure
of the outer container TA due to, for example, inadvertent loss of
internal pressure, or due to leakages, etc.
It will be observed that the flexible diaphragm DF is retained in a
location where it is unable to move too far either in a downward
direction or in an upward direction. When it is moved in an upward
direction, its upward movement is limited by the location of the
floating actuator AK within cap segment CP. On the other hand, when
the diaphragm DF is moved in a downward direction due to excessive
pressure on the upper side of the diaphragm DF, it will be
restrained by the lower inner wall of the chamber within cap
segment CP.sub.2 in which the diaphragm DF is positioned. Moreover,
the two limiting positions will define the relative positions of
diaphragm DF. This travel distance can be carefully adjusted for
any desired or pre-assigned values. The diaphragm DF may be made
rather sensitive and responsive to differential pressures of 10,
15, 20, 25 psi or less or more, as may be desired. On the other
hand, diaphragm DF, which may be made of corrugated stainless
steel, is able to withstand the available pressures under all
operating conditions developed either within the container TA or
container TB or both.
The diaphragm DF is a flexible diaphragm as already indicated, made
either of rubber or corrugated stainless steel and of any desired
thickness and rigidity so that it may be moved or expanded in
response to predetermined pressure variations. The diaphragm DF is
hermetically sealed against the cap segment CP.sub.2 so as to
completely isolate the fluid within the miniature container TB and
maintain that fluid isolated.
The miniature chamber TB is fully sealed as noted and may be sealed
hermetically by welding, brazing or other means, so that the
contents thereof may not be leaked out or altered. It may therefore
remain a permanent standard for maintaining a condition of balance
or equilibrium throughout the fire extinguishing system. Variations
in the internal pressure of the outer container TA are always
compared with the internal pressure of the standard miniature
container TB and significant changes are detected by the upward
flexure of diaphragm DF and the operation of the signal
circuit.
Although the structure shows the employment of two ports PT1 and
PT2 for transmitting fluid from container TA to the upper side of
diaphragm DF, it will be obvious that one port may be sufficient.
If desired, as already pointed out, any number of ports may be
employed for this purpose. Likewise, a single port PT0 has been
shown and provided on the underside of the diaphragm DF for
permitting the fluid in the container TB to constantly actuate the
diaphragm DF. Obviously, more than one port may also be employed
for this purpose.
The diaphragm DF, by being sealed into the cap CP by welding or
other means, cannot leak any of the fluidic contents of the
container TB into container TA, and vice versa. This is a most
important function because it always maintains the two fluids in
separate and independent containers. Furthermore, the diaphragm DF
is so oriented by its corrugations or other deformations that it
can be flexed many times in testing or otherwise operating the
equipment, without substantially affecting its long range
durability and operability. It remains, therefore, intact and
usable for long periods of time.
If desired, the cap structure CP and its flexible diaphragm DF and
the associated equipment may be arranged to couple the containers
of two complete fire extinguishers by arranging the diaphragm DF to
form a seal against both containers. In such an arrangement, the
fluids of both containers may be kept apart by the diaphragm, and
the fluids of the two containers would normally apply pressure
against opposite sides of the diaphragm. The microswitch MS, the
circuit W1, W2 and lamp LP would be caused to respond to the
movement of the diaphragm in response to a predetermined pressure
change in either container.
Although this structure has been shown and described as a mechanism
for comparing the contents of a container TA of a fire extinguisher
with that of the standardized micro-container TB, the arrangement
need not be embodied in or applied to a fire extinguisher, but may
be embodied in any other container whether or not employed for fire
extinguishing functions.
Although the equipment has been described as a mechanism for
indicating when the pressure of the fluid in the first container TA
falls below the pressure of the fluid within the second container
TB, the mechanism may also be used to determine and signify when
the pressure of the fluid within the first container TA exceeds
that of the container TB by a predetermined value. The microswitch
MP will be released whenever the pressure within container TA
exceeds that of container TB by a predetermined magnitude. This
condition will be indicated by the absence of illumination at lamp
LP. But when the pressure within container TA drops substantially
so as not to provide a predetermined differential pressure, then
the lamp LP will be illuminated to reveal that condition. In other
words, the mechanism of this invention may be employed to signify
pressure differentials in either direction -- always independent of
temperature variations encountered in the ambient external
medium.
FIG. 2 schematically shows a fire extinguisher to which the
invention may be applied. The structure of FIG. 2 includes a filler
valve FV and a discharge valve DV, both mounted on container TA.
This structure may be arranged and operated in accordance with the
principles set forth in the patent of J. R. Fiero, U.S. Pat. No.
3,552,495, issued Jan. 5, 1971 and assigned to the assignee of the
present application.
While this invention has been shown and described in certain
particular embodiments merely for illustration and explanation, it
will be apparent that the general principles of this invention may
be readily applied to other and widely varied organizations for the
practice of this invention.
* * * * *