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Description  |
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SUMMARY OF THE INVENTION
This invention relates to fire suppressant systems using pressurized Halon
1301 extinguishant or other liquid fire extinguishant having the ability
to extinguish slow growth fires or explosive type fires, e.g., fires
generated in military vehicles due to penetration of the vehicle fuel
tank(s) by enemy projectiles.
The invention concerns the mechanical design of a fire suppressant bottle
mechanism (including a unique bladder structure), and also a method of
sizing the bottle contents; i.e., selecting an optimum quantity of liquid
fire suppressant, and the most appropriate pressure for the pressurizing
agent.
With regard to the mechanical bottle design, the principal objects of the
invention are to provide a bottle-type fire extinguisher mechanism
wherein:
1. the bottle is orientable in any convenient attitude, e.g., horizontal,
inverted, upright, etc.
2. the liquid extinguishant discharge time is relatively short, e.g., less
than 95 milliseconds for a seven pound bottle at 70.degree. F.
3. the bottle mechanism includes a unique internal bladder for physically
isolating the liquid fire extinguishant from the gaseous pressurizing
agent.
4. the internal bladder is constructed to withstand a very fast stroke
without destruction of the bladder or associated mechanisms.
5. after liquid fire extinguishant has been discharged from the bottle new
liquid extinguishant can be pumped into the bottle without adding new
gaseous pressurizing agent, i.e., the original pressurizing agent can be
reused.
6. the bottle mechanism (with internal bladder) operates without dynamic
seals.
7. the mechanism operates satisfactorily at relatively high internal
pressures over a wide range of ambient temperature conditions.
8. the mechanism is designed to take into account compressibility
characteristics of the liquid fire extinguishant.
9. the mechanism can include discharge piping for transporting liquid fire
extinguishant from the bottle to remote area(s) requiring fire protection,
the bottle including an automatic flush valve operable to permit the
pressurizing agent to exert a driving force on liquid fire extinguishant
while it is flowing through the discharge piping.
With regard to the method of sizing the bottle contents, my invention has
for its principal objects a method wherein:
1. the relative quantities of liquid fire suppressant and pressurizing
agent are predetermined so that a satisfactory driving force is maintained
on the liquid during the entire liquid discharge time period (regardless
of the temperature at which the discharge process takes place).
2. the standby pressure of the system is maintained within a satisfactory
range even through the system is exposed to wide temperature extremes
(arctic to desert conditions).
3. the sizing of the liquid suppressant and pressurizing agent takes into
account the compressibility of the liquid component.
THE DRAWINGS
FIG. 1 is a longitudinal sectional view taken through one embodiment of my
invention.
FIG. 2 is a longitudinal sectional view taken through a second embodiment
of my invention.
FIG. 2a is a fragmentary sectional view on line 2A--2A in FIG. 2.
FIG. 3 is a sectional view taken through a third embodiment of my
invention.
FIG. 4 is a fragmentary sectional view showing the valve assembly of FIG. 3
in its standby position (with the bottle fully charged).
FIG. 5 is a fragmentary sectional view similar to FIG. 4 but showing the
valve assembly at the instant when liquid fire suppressant is discharged
from the bottle.
FIG. 6 is an elevational view of the FIG. 1 bottle mechanism and an
associated control valve mechanism.
FIGS. 7 and 8 are graphs usable to size the systems shown in FIGS. 1
through 6.
An understanding of the various embodiments of the invention shown in FIG.
1 through 5 will be facilitated by initial reference to semidiagrammatic
FIG. 6. The system shown in FIG. 6 comprises a bottle 10 having a flexible
elastic bladder 16 subdividing the bottle internal volume into two
variable volume chambers 8 and 9. Liquid fire extinguishant, such as Halon
1301 extinguishant, is charged into chamber 8; a pressurizing gas, such as
nitrogen, is charged into chamber 9. Neck area 15 of the bottle has a
control valve 30 screwed or otherwise affixed thereto. Metallic diaphragm
65 within control valve 30 normally retains the pressurized liquid within
chamber 8; bladder 16 is normally in its retracted (non-stretched)
condition designated generally by numeral 16A.
When an explosive squib within valve control section 62 is ignited annular
knife element 63 is driven rightwardly against the upstream face of
diaphragm 65. The diaphragm is punctured around its peripheral edge,
thereby enabling the pressurized liquid to flow from chamber 8 through
valve 30, as designated by numeral 67. The motive force for driving the
liquid out of bottle 10 is provided by the pressurized gas in chamber 9;
action of the pressurized gas causes bladder 16 to move from position 16A
to position 16B. Gas pressures in the neighborhood of 750 psi to 2500 psi
are contemplated, with 1500 psi being the preferred pressure at 70.degree.
F.
A piping system to distribute the liquid fire extinguishant to areas remote
from the bottle may be connected to exit opening 60 of control valve 30.
Alternately the liquid fire extinguishant can issue from exit opening 60
as a jet stream directly onto a fireball in the stream path.
The FIG. 6 arrangement differs from conventional "single chamber" bottle
systems heretofore used by the U.S. military in suppression of explosive
fires. In such single-chamber bottle designs, of the type shown for
example in my U.S. Pat. No. 3,915,237 issued Oct. 28, 1975, the gaseous
pressurizing agent (nitrogen) is introduced into the same space as the
liquid fire extinguishant; the intent is to let the gaseous pressurizing
agent occupy an upper portion of the bottle space, with the liquid
extinguishant occupying the lower portion of said space. However, some of
the pressurizing agent is undesirably dissolved in the liquid. For
example, it has been estimated that with temperatures near 70.degree. F.
as much as 62% of the nitrogen enters into solution with the liquid Halon
1301 extinguishant in the single chamber bottle designs. Use of a bladder
to physically separate the gaseous pressurizing agent from the liquid
Halon 1301 extinguishant avoids problems associated with the nitrogen
solubility phenomena.
In single chamber bottle designs the vapor pressure of Halon 1301
extinguishant (CF.sub.3 Br) is reduced by the mole fraction of nitrogen in
solution. Typically the Halon vapor pressure might be on the order of 161
p.s.i.g., with the nitrogen vapor pressure 589 p.s.i.g.. The amount of
nitrogen entering into solution is directly dependent on the nitrogen
partial pressure. Solubility effects can be visualized as being similar to
the action of carbon dioxide in water (carbonated soda water). During
liquid discharge from a conventional single-chamber bottle the dissolved
nitrogen tends to come out of solution as dispersed bubbles in the flowing
liquid. The bubbles can significantly reduce the effective flow rate of
the liquid Halon 1301 extinguishant in an action resembling vapor lock.
Use of a bladder within the bottle, as shown in FIG. 6, eliminates the
undesired flow retarding action associated with the presence of dissolved
nitrogen in the liquid Halon 1301 extinguishant.
The bladder is also advantageous in that it permits the use of higher
internal pressures in the bottle. With conventional "single chamber"
bottle designs the internal pressure is usually less than 800 p.s.i.;
higher pressures would undesirably increase the quantity of nitrogen in
solution, thereby reducing the effective driving forces. A high
temperature situation can be visualized, e.g., above 130.degree. F., where
all of the nitrogen is dissolved; the bottle is then liquid full. In such
a situation the nitrogen would have to come out of solution before
achievement of effective driving forces. Using a two chamber bottle design
(with separating bladder) the internal pressure can be relatively high,
e.g., 2000 p.s.i., (under the same total bottle volume conditions) with
corresponding increase in driving force on the liquid during the liquid
discharge process.
The two chamber bottle design can also make the bottle more versatile,
i.e., usable where the single chamber design could not be used. The two
chamber design can be mounted in a desired attitude or orientation, e.g.,
horizontally or vertically or an any intermediate inclination. Thus, in
the FIG. 6 design chamber 9 can be above or below chamber 8. In the
conventional "single chamber" bottle design the gaseous pressurizing agent
is required to be above the liquid fire-extinguishant; this requirement
imposes some constraints on how the bottle is to be oriented in the
vehicle or other area requiring fire protection. In some vehicles it would
be difficult to find space for a single chamber bottle, whereas the two
chamber bottle could be used without difficulty.
FIGURE 1 EMBODIMENT
In FIG. 1 there is shown a fire extinguishant mechanism comprising a
standard thick-walled bottle or container 10 formed of steel, ductile iron
or other material (which meets the Department of Transportation
requirements) suited to withstand proof pressures up to about 3000 p.s.i..
The bottle may be mounted in any angular position, e.g., upright,
horizontal, or inverted. A cup-shaped end cap 12 may be employed to
increase the bottle internal volume and thereby allow more propellant gas
to be used, if required, than a conventional bottle without the end cap.
End cap 12 advantageously provides for easy assembly of bladder 16 into
the bottle prior to charging operations. The elastomeric bladder
(membrane) 16 of hat-shaped configuration is anchored to the bottle by
means of an annular disk 11 clamped against bottle end face 7 by means of
annular threaded ring 19. Disk 11 overlies a bead 14 on the bladder to
securely anchor the bladder and seal the container against leakage.
Additionally disk 11 serves as a stop to limit movement of bladder 16 in a
right-to-left direction, but only during the initial Halon 1301
extinguishant charging operation.
A conventional fill valve 18 is carried on end cap 12 for admitting
(charging) propellant gas into the bottle. Safety valve 20 (containing a
non-illustrated rupture disk) is mounted on end cap 12; at some
predetermined pressure, e.g., 2600 p.s.i., the safety valve opens to
release propellant gas from the bottle to the ambient atmosphere. Under
normal conditions valve 20 remains in a closed condition. Pressure gage 22
measures the propellant gas pressure (chamber 9) and liquid fire
suppressant pressure (chamber 8). In the illustrated system the pressure
in chambers 8 and 9 are the same when the bottle is in its charged
condition.
The bottle may be initially charged with a predetermined mass of liquid
fire extinguishant, such as Halon 1301 extinguishant, by means of an
auxiliary filler valve on control valve 30. The control valve may be
constructed generally as shown in my copending U.S. patent application
Ser. No. 433,571, filed on Oct. 8, 1982 and now abandoned. The filler
valve may be constructed as shown in U.S. Pat. No. 3,491,783 issued in the
name of O. L. Linsalato on Jan. 27, 1970 (see valve 37). During the
operation of charging liquid into chamber 8 bladder 16 undergoes a
leftward motion (FIG. 1) toward disk 11. Disk 11 acts as a stop to prevent
motion of the bladder into cap 12.
After the system has been charged with Halon 1301 extinguishant (or other
liquid fire extinguishant) enough propellant gas (e.g., nitrogen) is
supplied through fill valve 18 so that the pressure exerted on the Halon
1301 extinguishant is greater than that required to keep the Halon 1301
extinguishant in a liquid state at all expected temperatures (e.g., arctic
and desert temperatures). Temperature-pressure relationships necessary to
maintain Halon 1301 extinguishant in the liquid (or gaseous) state are set
forth in a pamphlet by E. I. DuPont de Nemours & Company title "Handling
and Transferring Dupont's Halon 1301 Fire Extinguishants", Pamphlet FE-2A
dated May 1973 (see FIG. 2 on page 3 of the pamphlet).
Referring to attached FIG. 1, reference number 16c shows in dashed lines
the position that the bladder might take if bottle 10 were to be mounted
in a horizontal position; numeral 16A indicates in full lines the general
position taken by the bladder when the bottle is oriented vertically
(upright or inverted). Halon 1301 extinguishant, the preferred liquid for
the fire-extinguishant, has a relatively high coefficient of
compressibility (or low modulus of elasticity); therefore the bladder
position is affected to a certain extent by ambient temperature and
pressure changes. At high ambient temperatures the internal pressure
within the bottle increases; the volume of the liquid increases, while the
gas volume decreases, such that bladder 16 shifts to the left (FIG. 1). At
low ambient temperatures bladder 16 shifts to the right. FIG. 1 represents
an intermediate condition. When control valve 30 is opened the pressurized
nitrogen expands, propelling the bladder toward dashed line position 16B;
the liquid is driven out of the bottle through control valve 30.
The central area of bladder 16 is reinforced by means of a plate structure
that includes two plates 24 and 26 suitably grooved at their peripheral
edges to exert clamp forces on bead 14 of the bladder. A threaded stem 25
extends from plate 24 through plate 26 into a retaining nut 31. Side areas
of the bladder engaged with bottle side wall 5 are reinforced by the
bottle surface; during motion of the bladder from position 16A (or 16C) to
position 16B the side areas of the bladder undergo elastic deformation
(stretching) parallel to bottle axis 3. However the stretching forces on
the side areas of the bladder are substantially uniformly applied around
and along the bladder surface so that each incremental area is subjected
to only a moderate unit area force.
The central end area of the bladder on or near bottle axis 3 is reinforced
by plate structure 24, 25. As the bladder reaches the end of its stroke
plate structure 24, 25 abuts against the end surface of the bottle to
prevent bladder 16 from extruding itself through the opening provided by
neck area 15 of the bottle. Plate 26 preferably has a beveled face 27
mated to the angulation of the bottle end wall near neck 15, such that a
relatively large contact area is presented to the bottle surface (in order
to distribute the shock forces).
During the short time interval required to discharge liquid propellant from
chamber 8 through control valve 30 bladder 16 is subjected to very high
acceleration forces and deceleration forces. At the beginning of the
bladder stroke the bladder naturally has zero velocity; at the end of the
bladder stroke (position 16B) the bladder has a very high velocity.
Assuming 100 milliseconds to effect complete discharge of liquid through
control valve 30, the bladder can have a peak velocity approaching 40
ft/sec. Plate structure 24,25 reinforces the bladder and absorbs shock
forces, thereby preserving the bladder against destruction.
After the bottle mechanism has been used in a fire suppression operation
(e.g. to extinguish an explosive fire within a military vehicle) the
bottle mechanism can be recharged with new liquid suppressant without
adding a new charge of gaseous pressurizing agent. The new liquid is
admitted to chamber 8, using a modification of the procedure that was
originally used. Modification of the procedure is dictated by the fact
that when the original pressurizing agent in chamber 9 is reused the
liquid extinguishant must be introduced to chamber 8 at a sufficient
pressure to overcome the pre-existing chamber 9 pressure.
FIGURE 2 EMBODIMENT
In this embodiment of the invention the central bead 14 of elastomeric
bladder 16 is clamped between a plate 26 and an enlarged end 24' on an
elongated tube 36. Tube 36 is slidable along bottle axis 3 on an inner
guide tube 34 suitably affixed to end cap 12, as by a threaded connection
32. Tube 34 is a hollow tube having a number of ports or apertures 35
therealong, whereby the interior of tube 34 continually communicates with
chamber 9; grooves 37 in slidable tube 36 form fluid connections between
chamber 9 and the various ports 35.
Tube 34 constitutes a stationary guide for ensuring a straight line motion
of bladder 16 from its full line retracted position to its dashed line
extended position; the aim is to minimize the possibility of bladder
failure. Ports 35 prevent undesired depressurization of the zone within
tube 34, as might tend to slow the motion of tube 36 on tube 34.
Operationally the FIG. 2 embodiment is the same as the FIG. 1 embodiment.
EMBODIMENT OF FIG. 3 THROUGH 5
FIG. 3 illustrates the general features of a third embodiment of the
invention. FIGS. 4 and 5 are fragmentary sectional views showing an
automatic flush valve employed in the FIG. 3 embodiment.
The FIG. 3 embodiment is designed for use primarily in fire extinguisher
systems in which liquid fire extinguishant would be forced from container
10 through a piping system for distribution of the fire extinguishant to
an area remote from the container. A flush valve in the container (bottle)
is designed to automatically open at the end of the bladder discharge
stroke (position 16B), after which the pressurized gas flows from chamber
9 through the now-open flush valve to flush the liquid fire extinguishant
through control valve 30 and the piping system attached thereto.
Pressurized gas flows from container 10 through control valve 30 and the
associated piping, thereby maintaining a driving force on the liquid
extinguishant still in the piping when bladder 16 reaches the end of its
discharge stroke.
As shown in FIG. 3, a plate structure 24", 25" is clamped to bead area 14
of bladder 16. The plate structure is suitably affixed to a hollow tube
36' that is slidably arranged along bottle axis 3 within a stationary
guide tube 34'. Ports 35 are provided in the tubes for continuously
admitting pressurized gas from chamber 9 into the tube interior as bladder
16 moves in a left-to-right direction. The aim is to minimize the
possibility of semi-vacuum conditions within the tube interior as might
exert a retarding effect on tube 36' motion.
FIG. 4 shows the previously mentioned flush valve. Valve poppet 50 is
carried on a step 51 that is affixed to a spider 53 by means of a nut 100.
A compression coil spring 58 normally biases along axis 3 the valve poppet
to its closed position (FIG. 4). During standby periods the pressure in
chambers 8 and 9 are equalized, whereby the controlling force on poppet 50
is spring 58.
FIG. 5 shows the FIG. 4 valve at the end of the bladder power stroke. An
annular rigid wall structure 59 carried by plate 25" impacts against the
bottle end surface to limit the bladder motion; a ring of openings 61 may
be provided in wall structure 59 to accommodate fluid flow around the edge
of poppet 50. At the time when structure 59 impacts against the bottle end
surface the fluid pressure on the right face of poppet 50 is momentarily
reduced because the liquid fire extinguishant is no longer subjected to
the driving force provided by the pressurized gas in chamber 9. The unit
pressure on the left face of poppet 50 tends to be greater than the unit
pressure on the right face of the poppet; the pressure imbalance tends to
move poppet 50 to its FIG. 5 open position.
Poppet 50 may also tend to be opened because of inertia effects. Thus,
although structure 59 impacts the bottle end surface to limit rightward
motion of plate structures 24" and 25", poppet 50 motion is not directly
affected by the impact action (except for the resilient connection
provided by spring 58). Therefore inertia forces generated by bladder
movement tend to keep poppet 50 and the attached parts moving rightwardly
even after structure 59 impacts the bottle end surface. Irrespective of
the exact mechanism, valve 50 assumes an open condition when the bladder
reaches the end of its stroke. Gaseous pressurizing agent flows from
chamber 9 into tube 36' and around poppet 50 as shown by the arrows in
FIG. 5. The pressurizing agent thus maintains a driving force on the
liquid fire extinguishant while the extinguishant is moving through the
distribution piping (attached to the exit opening of valve 30). The action
causes all (or substantially all) of the liquid to be applied to the
fireball. It also maintains the Halon 1301 extinguishant in a pressurized
condition, such that it has lessened tendency to flash vaporize before
exiting from the piping system.
ADVANTAGES OF THE BLADDER IN TWO CHAMBER BOTTLE DESIGNS
The description of the FIG. 6 structure identified general advantages of
two-chamber bottle (container) systems. Such two chamber systems are
already known; see for example U.S. Pat. No. 4,194,572 to A. J. Monte,
wherein a slidable piston is used as a barrier between a gaseous
pressurizing agent and a liquid fire extinguishant. The use of a flexible,
stretchable bladder is believed to be advantageous over a piston in that
the bladder is not required to have moving (dynamic) seals.
During standby periods the barrier (bladder or piston) is required to move
back and forth in accordance with temperature changes, i.e. resultant
changes in the pressure of the pressurizing agent. When a piston is used
as the movable barrier there is a potential transfer of fluid between the
gas and liquid chambers (9 and 8 in the attached drawings). Even when the
walls of the cylinder are of a mirror finish quality the dynamic seals do
not completely wipe the walls clear of liquid during piston movement in a
given direction; on return movement of the piston the liquid film on the
cylinder wall can be transferred into the gaseous phase. In a somewhat
similar fashion gas can migrate across the piston-cylinder interface to
dilute the liquid. Water impurity in the nitrogen could then possibly
react with the Halon 1301 extinguishant to form corrosive liquids.
The piston is also believed to have some disadvantages during the liquid
discharge operation, i.e. a retarding action on piston motion. Over and
beyond piston-cylinder friction, there are inertia effects associated with
relatively heavy metal pistons (compared to relatively light elastomeric
bladders), and piston cocking effects (if the piston length is small in
relation to piston diameter).
SIZING THE BOTTLE CONTENTS
I use the term "sizing" to mean the process of determining the optimum gas
pressure, optimum quantity (mass) of liquid Halon 1301 extinguishant, and
optimum bottle size (volume), to be employed in order to satisfy a given
fire suppression requirement, under a range of different operating
temperatures (arctic to desert). Unless the three variables are properly
"sized" the total liquid flow and/or liquid discharge rate (i.e. time to
empty the bottle) will be less than optimum. For example, in the FIG. 1
system, if a relatively small mass of liquid Halon 1301 extinguishant is
charged into chamber 8 (at 70.degree. F.) bladder 16 will have a standby
position to the right of that shown in FIG. 1; enlarged chamber 9 will
contain a large volume of pressurizing agent. When valve 30 is opened the
liquid halon is expelled at a rapid rate. However because only a small
mass of Halon 1301 extinguishant was initially charged into the bottle
there may be insufficient total liquid flow to extinguish the fire.
If a relatively large mass of liquid Halon 1301 extinguishant is initially
charged into the bottle (at 70.degree. F.) bladder 16 will have a standby
position to the left of that shown in FIG. 1. When valve 30 is opened the
pressurizing agent in chamber 9 experiences a significant volume change in
order to fully expel the liquid out of the bottle. Such a large volume
change is accompanied by a severe pressure reduction. The liquid flow rate
during the latter stages of the liquid discharge process may be
undesirably low, resulting in an insufficient average flow rate and
perhaps in flashing of the Halon 1301 extinguishant, with associated
retardation of liquid flow rate.
It might be thought that good results could be obtained merely by raising
the charging pressure of the pressurizing agent to a very high value, e.g.
4000 p.s.i. However safety factors and strength of materials
considerations tend to set an upper limit on the gas pressure. Federal
regulations on safe transportation of charged bottles also set practical
upper limits on bottle pressures. Under current conditions the practical
upper limit is about 2500 p.s.i. It is contemplated that safety valve 20
(FIG. 1) will be set to open at 2650 p.s.i. for a design maximum operation
pressure of 2500 p.s.i.
A principal use of the bottle system is in military vehicles subject to
ambient temperature extremes, ranging from a low temperature of about
-65.degree. F. in the arctic to a high temperature of approximately
160.degree. F. in the desert. It is believed impractical to vary the
bottle charge when going from one temperature extreme to the other.
Therefore a given bottle system must be sized (charged) to provide a
suitable fire-extinguishant flow over a wide temperature range, e.g.
between -65.degree. F. and +160.degree. F.
High ambient temperatures tend to raise internal pressure (and liquid
extinguishant volume) within the bottle, whereas low temperatures tend to
lower the bottle pressure (and liquid volume). If the ambient temperature
should be such as to raise the internal pressure above the setting of
safety valve 20 (e.g. 2650 p.s.i.) the valve will be actuated to
prematurely release some or all of the gaseous pressurizing agent, thus
reducing the bottle's fire-suppression capability. If the ambient
temperature should be such as to lower the internal pressure below a
satisfactory value the pressuring agent will exert insufficient driving
force on the liquid fire extinguishant during the liquid discharge
process. The effect of ambient temperature change should be taken into
account when sizing the bottle system.
Another factor to be considered is compressibility of Halon 1301
extinguishant, the presently preferred liquid fire extinguishant, when
initially charging the system. Halon 1301 extinguishant has at least ten
times the compressibility of water and similar liquids. The bulk modulus
of elasticity of water at 70.degree. F. is approximately 250,000 p.s.i. to
achieve a unit volume change. In contrast, the bulk modulus of elasticity
of Halon 1301 extinguishant at the same temperature is less than 20,000
p.s.i. per unit volume change. Compressibility characteristics can affect
the pressures and volumes of the liquid extinguishant and gaseous
pressurizing agent achieved when the system is initially charged. As
inferred in FIG. 7, high charging pressures (at any given charging
temperature) tend to densify a given mass of Halon 1301 extinguishant into
a small initial displaced volume.
A smaller initial displaced volume of liquid Halon 1301 extinguishant means
a greater initial volume of gaseous pressurizing agent, hence a greater
average driving force on the liquid Halon 1301 extinguishant during the
liquid discharge process (because the pressurizing agent then experiences
a proportionally smaller volume change during the discharge process). In
general, if compressibility (elasticity) characteristics of the liquid are
taken into account in the "sizing" process it is possible to increase the
mass of Halon 1301 extinguishant charged into any given size bottle
(compared to the mass of Halon 1301 extinguishant calculated without
taking into account the compressibility factor).
Sizing of the system should be such that a satisfactory driving force is
maintained on the liquid fire extinguishant during the entire course of
the liquid discharge process. If the pressure of the gaseous pressurizing
agent is at any time allowed to drop below a value where the driving force
is less than the vapor pressure of the liquid Halon 1301 extinguishant
there may be Halon 1301 extinguishant vaporization (boiling) and
significant slowdown of the Halon 1301 extinguishant flow. The halon vapor
pressure is temperature-dependent, being about 214 p.s.i.a. at 70.degree.
F. and 575 p.s.i.a. at 153.degree. F. Whatever the ambient temperature
condition, it is recommended that in so-called piped systems (FIG. 3) the
system be sized so that the final end pressure of the gaseous pressurizing
agent (i.e. at the end of the liquid discharge process) is at least about
200 p.s.i. or more above the Halon 1301 extinguishant vapor pressure at
the existing temperature condition; in such piped systems the pressurizing
agent is used not only to expel the extinguishant from the bottle, but
also to flush liquid fire extinguishant through the piping system. In
direct discharge systems (FIGS. 1 and 2) the final end pressure may only
have to be about 40 p.s.i. above the Ha | | |
