FR2662608A1 - FRANGIBLE CARTRIDGE FOR EXTINGUISHING ADDITIVES IN PRESSURIZED WATER EXTINGUISHERS AT THE TIME OF USE WITH COMPRESSED GAS. - Google Patents

Abstract

The cartridge (5) is disposed floating freely in water (1a) which fills a water extinguisher (1, 2), put under pressure for use by perforating the diaphragm of a capsule (13) of liquid carbon dioxide, to be forced through the plunger tube (6) and the nozzle (6a). The cartridge (5) comprises a tubular body (10) made from polyethylene with an opening at the lower end (12) which is closed off by a cap (13) formed from an aluminium foil with a layer of polyethylene on the inner side, thermally welded to the edge of the body. An additive (14) of the floating-film-forming agent type is contained at the lower portion of the body (10) with a free space (15) above it which ensures a positive buoyancy and vertical immersion stability. During the rise in pressure, towards 0.4 MPa, the cap (13) tears and the inrush of water into the body disperses the additive.

Description

i "Frangible cartridge for extinguishing additives in fire extinguishers

  water pressurized at the time of use by a compressed gas "The invention relates to a frangible cartridge for a fire extinguisher pressurized water by releasing, in the extinguisher, a propellant compressed in the preceding moments the use of the extinguisher, cartridge containing additives capable of improving the properties

water extinguishers.

  Such frangible cartridges are known, which are connected to the source of propellants; when the extinguisher is put into operation, the pressure of the propellant released releases the cartridge, which spills the additives into the water

are thus mixed with this water.

  These additives can be of the surfactant type, to promote the formation of a foam and the contact of water with the substances on fire; currently used as additive, fluorocarbons capable of

  form a floating film on the surface of the water.

  These additives have a corrosive nature which prevents them from being dissolved or suspended in water at the origin, on pain of seeing the extinguisher put out of use by corrosion within a period which may not not exceed one year The frangible cartridge, made of an inert material vis-à-vis

  additives, avoids this premature decommissioning.

  In addition, it allows precise dosing of additives,

  and ensures their conservation over long periods.

  However, they can be criticized for complicating the structure of the fire extinguisher, with diversions of gas pipes to ensure the bursting of the cartridge, and tight seals to connect the cartridge to the pipeline.

  gas, and therefore increase the cost price of the extinguisher.

  In addition, checking the good condition of the extinguisher required periodically, practically leads to the replacement of the cartridge, the sealing of the seals no longer being ensured after disassembly. Moreover, new cartridges generally have a device for

  frangible membrane, guaranteeing their condition.

  The invention proposes, while retaining the advantages of known frangible cartridges, to overcome the drawbacks which have just been reported. To this end, the invention provides a frangible cartridge for a water extinguisher pressurized by releasing, in the extinguisher, a compressed propellant gas, in the moments preceding the use of the extinguisher, cartridge containing additives suitable for improving the extinguishing properties of water, characterized in that it comprises an oblong, rigid tubular body with an open end, this end being closed by a cover provided for tearing under a determined differential pressure less than the maximum pressure undergone by water after release of the propellant gas, the volume of additive in the cartridge being at most 80% of the volume

inside the body.

  The rupture of the cover being effected under the effect of an overpressure external to the cartridge, the latter does not require any connection with another member of the extinguisher. included no frangible cartridge In addition this cartridge remains in its original state until the use of the extinguisher to fight a fire During periodic visits of the extinguisher, it will suffice to check the integrity of the cartridge , and it will only be replaced if its integrity

is doubtful.

  The invention proposes a certain number of secondary provisions, which contribute to improving the results

essential techniques.

  Thus the cartridge will be provided with a positive buoyancy and placed free in the extinguisher; its length will be such that, arranged with its end open towards the

  low, it will not be able to turn over in the extinguisher.

  The cartridge will preferably be made of translucent polyethylene, with the aluminum foil cover lined with polyethylene on the side facing the inside of the body, the polyethylene lining being thermally welded to the edge. On the one hand, the additives do not react. not on polyethylene, which ensures the life of the cartridge; and the level of additive in the cartridge is

vis 8 lable visually.

  This cartridge is particularly suitable for fluorocarbon additives mainly, in particular of the type forming a floating film. The rupture of the cover is provided for a differential pressure of approximately 0.4 M Pa, ie 4 bars, this pressure being both sufficiently distant of the maximum pressure developed in the extinguisher immediately before its use so that the rupture is followed by an effective dispersion of the additives contained, and sufficiently high so that a premature accidental rupture is not to be feared, and that the normal rupture

  determines an effective flush in the cartridge.

  Preferably, doses of additive representing at least 1% by volume of the nominal volume of the extinguisher will be used; more precisely, for a fire extinguisher of 6 liters nominal, the volume of the cartridge will be milliliters, and for a fire extinguisher of 9 liters and more, the volume of the cartridge will be approximately 1.1 t in volume of the

nominal volume of the fire extinguisher.

  The characteristics and advantages of the invention

  will be more apparent in the description which follows,

  by way of example, with reference to the accompanying drawings in which: FIG. 1 is an axial section of the upper part of a fire extinguisher comprising a cartridge according to the invention; Figure 2 is a section through a cartridge according to the invention. According to the embodiment chosen and represented in the figures, a cartridge 5 for additive of extinguisher liquid is placed freely in an extinguisher

  classic water, sprayed by pressurized gas.

  The fire extinguisher comprises a body 1 of tubular shape with domed ends In the upper end dome is fixed a head 2 On this head 2 are fixed, towards the inside of the body 1, a capsule 3 confining a load of liquid carbon dioxide, and a dip tube 6, parallel to the axis of the body 1 and which extends approximately over the total height of this body This dip tube 6 is extended,

  after crossing of the head 2, by a projection nozzle 6 a.

  The head 2 comprises a percussion mechanism 4, with a striker 4 able to perforate a diaphragm for closing the capsule 3, held by spring away from the diaphragm, and

  likely to be pushed in by folding down a lever 4 b.

  This arrangement is conventional and thus works to put the extinguisher into service, the lever 4 b which folds the striker 4 a into the diaphragm closing the capsule 3 At the end of the lever 4 b being pressed in, the part of the striker 4 a on which carries the lever 4 _ penetrates, under the effect of its spring, into a housing provided in this lever 4 b; the striker 4 a emerges from the diaphragm, and thus lets the carbon dioxide spread in the space located under the head 2 above the level of the filling water, while the lever 4 b is locked in position

  folded down, which indicates that the extinguisher has been used.

  Additives for water are commonly added to

  improve its extinguishing properties, such as surfactants

  active, or products capable of forming thin surface layers on the surface of water Such additives may have insufficient stability in contact with water Also the commonly used solution consisted in enclosing the additives in a cartridge capable of bursting under the effect of an internal overpressure, and to connect this cartridge by a pipe to the chamber which surrounds the striker 4 a When the capsule 3 releases the propellant carbon dioxide, this penetrates into the cartridge which

  bursts and in turn releases its contents into the water.

  According to the invention, the cartridge 5 is formed of a body 10, tubular, oblong, of rigid polyethylene, with a closed upper end 11 substantially hemispherical, surmounted by a ring 16 The lower end 12 is closed by a cover 13 , consisting of aluminum foil 13 a filled with a layer of polyethylene 13 b, on the inside of the cartridge 5 This layer of polyethylene allows the waterproof fixing, by welding

  thermal with the end edge 1, of the cover 13.

  In the example shown, the body 10 has internal and external diameters of 35 and 40 mm respectively. The total height is approximately 146 mm, ring

  included The internal volume of the body is approximately 125 ml.

  A volume of additive 14 was enclosed in the cartridge, here a floating film-forming agent (Afff), which is a fluorinated hydrocarbon sold by the company 3M under the commercial designation FC 3041. In the example described, the quantity of fluorinated hydrocarbon is approximately 90 ml, and occupies, the cartridge being vertical, a height of approximately mm A bead 14 a, in excess of the body 10, marks the level of the surface of the additive 14 The body polyethylene being translucent, it will be possible to control

  the cartridge contains the desired volume of additive.

  This additive has a density between 1.2 and 1.3 The volume of additive 14, and of free space 15 above this additive, are such that the cartridge has positive buoyancy in water, and that , abandoned with the cover 13 at the bottom, this cartridge is immersed up to the large circle of the dome 15 a, approximately, in the position

shown in Figure 1.

  Note that the oblong shape of the body ensures that the center of pressure of the water is higher than the center of gravity of the filled cartridge, so that its vertical floating position is stable, as long as the cartridge is not tilted to the vicinity of

  horizontal, under the effect of an external action.

  However, a fire extinguisher being exposed to be handled and put in any position, there would have been a risk

  the cartridge turns over and floats in the air.

  This is in fact prevented, the cartridge being unable, due to its length relative to the diameter of the extinguisher body, to turn over in the space left free in the extinguisher body 1, between the wall of this body and the internal extinguisher organs, such as dip tube 6 and capsule 3. The thickness of the cover is determined in such a way that it tears under the effect of an external pressure of 0.4 M Pa (4 bars) It will be noted that, on release of the propellant gas (carbon dioxide), the pressure in the extinguisher, after percussion of the capsule, gradually rises to 1.5 M Pa (15 bars),

  and reaches 0.4 M Pa in about 1 second.

  It will be noted that the dispersion of the additive in the contents of the extinguisher could appear, a priori, less effective following a rupture under the effect of an external overpressure than under the effect of an internal overpressure. , there is no significant difference in the effectiveness of the mixture under the effect of an explosion and an implosion. It will be noted that the rupture of the seal occurs in the zone of connection with the end edge 12 of the body, therefore asymmetrically with respect to the axis, and that the volume 15 is suddenly reduced when the water bursts into the cartridge, which causes considerable turbulence, favorable to the dispersion of the additive. It will be appreciated that the installation of the additive cartridge 5 is done simply by introducing it, cover 13 at the bottom, into the body 1 filled with water, before adjusting the head. The structure of the extinguisher is also simple. than that of an extinguisher where the additives are mixed with the filling product, while no corrosion of the extinguisher body

is not to be feared.

  Furthermore, during the periodic checks of a fire extinguisher, it will only be necessary to change the cartridge if it is found that the volume of additive inside is incorrect, which can be done at once at a glance, while, with a burst cartridge, disassembly of the cartridge

  for verification practically requires its change.

  It will of course be understood that the ring 16 is used, together with a hook tool, to remove the cartridge from the body 1, either during the checks o it floats in water, or for recharging the extinguisher

  after use, o the cartridge rests at the bottom of the body.

  The cartridge which has just been described can be used indifferently in fire extinguishers with a nominal capacity of 6 and 9 liters; for higher capacities, cartridges of higher volume will be used, it being understood that provision must be made for around 1% by volume of additive relative to the nominal capacity of the extinguisher, and that the free volume must be sufficient to give the cartridge positive buoyancy and stable balance

upright.

  Of course, the invention is not limited to the examples described, but covers all the variants

  in the context of the claims.

  This applies to both the dimensions of the cartridges and the nature of the additives,

filling and propellant.

Claims (1)

CLAIMS 1 Frangible cartridge <5) for water extinguisher pressurized by release, in the extinguisher <1), of a propellant gas (3) compressed, in the moments preceding the use of the extinguisher, cartridge containing additives capable of improving the extinguishing properties of water <la), characterized in that it comprises an oblong tubular body <10), rigid, with an open end <12), this end being closed by a cover <13 ) intended to tear under a determined differential pressure lower than the maximum pressure undergone by the water after release of the propellant gas, the volume of additive <14) in the cartridge being at most 80% of the interior volume of the body ( 10). 2 Cartridge according to claim 1, characterized in that it has a positive buoyancy, and is disposed free in the fire extinguisher. 3 cartridge according to claim 2, characterized in that it is disposed in the extinguisher <1) with the cover (13) directed towards the bottom, its body (10) being long enough to prevent a reversal in space left free for water (1 l) in the extinguisher <1). 4 Cartridge according to any one of claims 1 to 3, characterized in that it is molded in translucent polyethylene, the cover <13) consisting of an aluminum sheet <13 a) filled with a layer of polyethylene <13 b), on the side of the body, thermally welded on it. Cartridge according to claim 4, characterized in that the body extends (10), on the side opposite the open end, by a gripping ring (16). 6 Cartridge according to any one of claims 1 to 5, characterized in that the additive <14) is mainly a fluorinated hydrocarbon said agent forming a floating film. 7 Cartridge according to any one of claims 1 to 6, characterized in that the cover <13) is designed to rupture under a differential pressure of about 0.4 M Pa. 8 cartridge according to any one of claims   1 to 7, characterized in that the internal volume of the body (10) is at least 1 * of the nominal volume of the extinguisher. 9 cartridge according to claim 8, characterized in that the nominal volume of the extinguisher being 6 liters,   the internal volume of the body is approximately 0.1 liters.   Cartridge according to claim 8, characterized in that, the nominal volume of the extinguisher being at least 9 liters, the internal volume of the body is approximately 1.1% of this nominal volume.