Note: Descriptions are shown in the official language in which they were submitted.
~0~2069
PRESSURI ZED BARRIER PACK
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The present invention relates to the manufacture
of valved containers for dispensing viscous products at
an initial or charging pressure of only 6 to 40 psig, depending
generall~ on the dsgree of viscosity o the product. : :
The invention is concerned particularly with products
having a minimum viscosity of lO,OOO cps, but whose viscosity
may bs as high as SOO,OOO cps. or more; and provides articles
of manuacture in the form of valved pressurized containers
of low pressure and hence of practically complete safety,
and preerably pressurized containers wherein the product
is separated from the propellant by a disc, piston or collapsible
bag.
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A novel form of discharge valve is employed which
affords such a large cross-sectional flow area that a satisfactory
rate of flow through the valve is attained despite the low
propellant pressure. By reason of the reduced pressure,
the wall of the container, when o metal, can be greatly
reduced in thickness as compared to pressurized containers
charged at 100 psig or higher, so that ln addition to the
lower cost of the reduced pressure, still further economy
results from the use of smaller weights of metal, while at
the same time wastage of metal is reduced. Similar economies
are effected in the case of container walls made of plastic,
laminates, and other materials including paper having surfaces
impervious to liquids and gases.
BACKGROUND OF THE INVENTION
In order to understand the invention, it is necessary
first to consider the ~egulations of the Department of Transpor-
tation as given in Tariff No. 30, entitled "Hazardous
Materials Regulations of the Department of Transportation",
including "Specifications for Shipping Containers'~.
The above regulation in Section 173,306 recognizes
two types of pressure systems for metal containers.
1. For compressed gases, the container must
withstand pressure of three times the pressure at
70 F.
2. For liquefied gases, the container must
withstand one and one-half times the-eq~i~ibrium pressure
at 130 F.
In determining the pressure requirements for barrier
containersJ account must be taken of the fac~ that the initial
volume in the container not filled with product is about
one-third of the total volume, so that if compressed gas
is used, the initial pressure is three times the final (minimum)
pressure. For example, if for a given product, a minimum
pressure of 33 psig is needed (and this is also, of course,
the final pressure), an initial pressure o~ 99 psig is required
and the container must withstand a pressure of three times
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99 or 297 psig. Heretofore, inert gas propellants, when
used9 were of this magnitude, i.e., 90-100 psig.
When a liquefield propellant is used in order to
maintain 33 psig at 70 F, it will have a pressure of ca.
100 psig at 130 F, and the container will have to withstand
a bursting pressure of ca. 150 psig. To maintain an average
of 66 psig at 70, a bursting strength of 250 psig will
be needed.
Valved pressurized containers have for the most
part been designed or the discharge of atomized sprays
of low viscosity fluids or for the discharge of foaming
low viscosity fluids. In either case, the use of initial
pressures at 70 F of ca. 35 psig for li~uefield gases ~volatile
liquids) or 100 psig for compressed gases was necessary~
in order to obtain atomization or foaming. (The use of
lower pressure liquefield gases in glass containers for
the atomization of perfumes and ~he like required the use
of high-priced propellants and valves.)
When the use of barrier pressure dispensers for
viscous fluids started some twenty years ago and up to the
present time, the only available valve and containers were
the small orifice valves and high pressure containers and
these have been and are still in use today. The use of
these containers made it necessary to warn the consumer
against leaving the containers exposed to sunlight and against
throwing them into incinerators or open fires because of
the danger of explosion. The prior containers, therefore,
had to be made of rigid heavy gauge metal which increased
their cost of production and transportation, and also made
it difficult to eliminate denting and the by-pass or escape
o~ the propellant.
BRIEF SUMMARY OF T~IE INVENTION
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The present invention comprehends, as an article
of manufacture, a self-contained, sealed, pressurized barrier
container formed of flexible material. The container has
a wall which is sealed at one end and has a discharge valve
at the other end. The container has a piston serving as
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a gas-tight sealing barrier which deines two chambers.
The first chamber communicates with the valve and contains
a product for discharge at the pressure of a propellant
within the other chamber o~ the container. The container
is of such reduced strength that it could not withstand
an internal pressure in the container greater than 120 psig.
The wall of the container however is thick and strong enough
to contain the internal pressure to 120 psig and is thin
enough so that even at a low internal pressure the piston
may move through the container. The container wall may,
during such movement, somewhat deform and restore itself
if it had been deformed befoTe the piston had moved therethrough.
The piston has such strength as to be able to conform to
the wall of the container and the container wall is sufficiently
deformable that the piston maintains its seal with the container
wall as the piston moves through the container. The valve
is constructed, on opening, to afford an effective flow-
through cross-sectional area allowing a useful rate of discharge
of at least 0.8 g per second at the high internal pressure
and maintains an effective flow rate at reduced pressures
following incremental discharges from the container.
The invention further teaches the adaptability
of a container body suitable for use in the manufacture
of a valved, self-contained, sealed, pressurized container.
The container is sealed at one end and open at the other
end for receiving the product to be discharged as well as
receiving a control valve for manually regulating the discharge
of the product. The container has a bottom wall provided
with a port for receiving a propellant under pressure.
The container, as previously described, has enough strength
to withstand an internal pressure of up to 120 psig. The
container is made of flexible material such that dents are
capable o~ being straightened out by the internal pressure
and the passage of a slidable barrier piston. The piston
serves as a separator between a to-be-dispensed product
introduced through the open end and a propellant introduced
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through the port in ~he bottom wall. The container is thin
enough so that even at low internal pressure, the piston
may move through the container and during such movement may
somewhat deform and restore the container wall if it had
been deformed before the piston had moved therethrough.
The barrier piston seals the container wall along its full
height and has such strength as to conform to the wall of
the container. The container wall is sufficiently deformable
that the piston maintains its seal with the container wall
as the piston moves through the container.
The method of filling such self-contained, sealed,
pressurized container is also taught. The method of filling
the container with a quantity of a product to be dispensed
and with a propellant comprises the steps of providing an
open top container. The container has the previously described
chacteristics including a charging port and barrier piston.
The product to be dispensed is charged through the open end
into the space above the barrier piston. A valve assembly
is then sealed to the upper edge of the container. A gaseous
propellant is then charged into the space below the barrier
piston until a pressure of 6 to 40 psig at room temperature
is reached. Alternatively, a liquid propellant is charged
into the space until a pressure of 6 to 24 psig at room temperature
is reached. The charging is then to be sealed.
By way of a particular example, products of high
viscosity of, say 10,000 cps and above, are packaged in a
container at initial compressed gas pressures of ca. 6 - 40
psig at 70 F or initial liquefield gas pressures of ca.
6 - 24 psig at 70 F.
The 6 psig compressed gas requires a bursting strength
of three times or 18 psig, and the 6 lb. liquefield gas requires
a bursting strength of one and one-half times the pressure
at 130 or 60 psig. The 40 psig compressed gas requires
a bursting strength of 120 psig, and the 24 psig lique~ied
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gas also re~uires a bursting strength of 120 psig. Containers
of the present invention accordingly do not need to have
a bursting strength higher than 120 psig.
Since a compressed gas at an initial pressure of
40 psig gives a final pressure of ca. 13 psig, the use of
lique~ield gas at 13 psig would give the same final flow
characteristics. The bursting pressure required for 13 psig
liquefied gas is 75 psig, but if the liquefied gas is used
in a novel way, described below, the bursting pressure required
can be reduced even further.
According to a further feature of the invention,
the quantity and type of liquefield gas to be used are calculated
and determined, so that it is completely evaporated before
the 130 F temperature is reached, whereupon it then acts
as compressed gas, giving a lower pressure at 130, and
above, than would otherwise be reached (i.e., with a continuing
supply of liquid propellant), and therefore allowing even
thinner walls for the package and even greater safety.
By way of example, and in accordance with the
invention, there is employed, for a 6 fluid oz. container,
a quantity of a volatile liquid fluorocarbon propellant,
such as "Freon", less than 4 g. within the skirted piston,
described hereinafter, and having a volume of about 2 oz.,
in contrast to the 7 to 10 g. employed in current practice,
for the 6 oz. can, the amounts varying somewhat, depending
on the specific fluorocarbon. Similar reductions in the
amount of a volatile liquid hydrocarbon or other liquid
propellant can be made in accordance with the present invention
for the purpose stated.
The limited quantity of volatile liquid propellant
can be mixed with air, nitrogen or carbondioxide, which on becoming
mixed with the maximum amount of vapor originating in the liquid
propellant, will yield a mixture of gas and vapor having
only the incremental increase in pressure per degree of
increase in temperature, according to the gas laws. Hence 9 .'
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when temperature rises, the liquid propellant is completely
evaporated at a pressure which is considerably below the
legal limitations on pressures.
Also, according to the invention, valves of increased
flow-through cross-section are used, while the container
is made of much thinner metal than heretofore, similar
to the con~ainers for beverages, or a combination of metal
foil and cardboard, or of plastic or laminates of cardboard
and plastic film can be used, so that the cost of a valved
container of 6 - ~ oz. capacity is in the neighborhood
of 10 - 12 cents in contrast to the cost of 17 - 21 cents
for the present day valved container. In fact, a 16 oz.
valved container would cost only about 13 cents, as compared
to about 25 cents for a present day valved container of
equal volume, if such were available, which it is not, ~ `
owing to the prohibitive cost. Since the retail cost to -
the consumer is from 3 to 5 times the manufacturing cost,
savings to the consumer of from 20 cents to 35 cents per
package are feasible.
If the cost of discarding dented containers and
malfunctioning containers is also included, an even greater
saving is possible since the invention also minimizes malfunc-
tion and denting.
In contrast to prior pressurized containers,
with or without barrier, the above invention accordingly
presents the following:
1. Economic advantages - lower cost.
2. Safety ad~antages - lower pressure.
3. Ecological advantages, i.e., less material is
used per container, and the use of metals and plastics is
conserved.
4. Denting problem is solved.
DESCRIPTION OF T~E FIGURES OF THE DRAWING-
In the accompanying drawing:
Fig. 1 is a central section, partly in elevation,
of a low pressure barrier container constructed in accordance
with the invention.
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Fig 2 is an enlarged view, in central longitudinal
section, of the tilt discharge valve in the closed condition.
Fig. 3 shows the valve of Fig. 2 in the open
condition.
Fig ~ is a central section through a modified
form of valve.
Fig 5 is a central section through a further
modification.
Fig. 6 is a view similar to Fig 1 of a modified
container constructed with an integral bottom.
DESCRIPTION OF PREFERRED FORM OF THE INVENTION:
.
Referring to Fig. 1, the container is indicated
at 10 and is provided with a cylindrical wall 10a. It
houses a barrier in the form of a piston 11 having a depending
skirt 12. The bottom 13 of the container is sealed to
the body OT wall of the container by double seaming, as
indicated at 14
The product space 10b of the container is filled
with the product through the open cylinder at the top thereof
and prior to the installation of the valve 15. After the
valve structure has been sealed to the top of the container
(the valve being in the closed condition), the space 10c
below the piston 11 and within the skirt 12 is charged
with a quantity of propellant at a pressure of 6 to 40
psig through a port 16 ~hich is thereafter closed by a
plug 17 of rubber or the like.
In accordance with the invention, and by virtue
of the reduced internal pressure, the cylinder or shell
of the container, and also the bottom wall thereo~, are
made considerably thinner, and thus of lower weight, than
such parts have heretofore been made for pressurized containers,
whether of metal, plastic, paperboard or the like. Thus,
the cylindrical body 10 may be made of aluminum, as in
beer and soft-drink cans, with a wall thickness of approximately
0.005 inch, in contrast to the approximately 0.015 lnch
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thickness of a standard aerosol can.
The tubular body 10 of the container can also
be formed of extruded thermoplastic material with a wall
thickness of 0.015 inch to 0O030 inch, or it may be made
of cardboard with a facing of plastic or metal foil, or
having a resin-treated surface impervious to gases and
liquids.
There may be provided sufficient clearance between
the skirt 12 and the interior surface of the container
lOa to allow some of the product to enter the clearance
space and form a seal between the propellant which is contained
in the space lOc and the product occupying the space lOb
above the piston.
With the container filled at reduced pressure
as above described, there is employed a discharge valve
capable of delivering the product at an acceptable ~ate
both at the original pressure and even as the pressure
falls on successive discharges.
Satisfactory valves for use in combination with
the above-described containers and having the necessary
high flowthrough capacity within the limited confines of
the valve cup, or equivalent structure, are illustrated
by way of examplei in Figs. 2 to 5.
The valve body includes a metallic, preferably
aluminum, frame or cup 19 which can be crimped to the top
edge of the body lOa, as indicated at 20, or double-seamed
to the top edge of the cylinder, as shown at 20a in Fig.
6.
Referring particularly to Fig. 2, the valve includes
the body of resilient rubber 21, or the like, which is
sealed to the stem 22 through which the product is discharged
on opening of the valve. The body 21 includes a bowed
portion 23 of annular cross-section whose upper edge abuts
against the shoulder 24 on the stem 22, thereby providing
a seal at such region, and also a point of compression
when the stem is tilted. The portion 23 of the valve body
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is arched downwardly and is then turned inwardly, as sho~
at 25, to form a further seal with the bottom portion of
the stem 22. The body 21 has an extension in the horizontal
direction to form an annular seat 26 whose function will
be described hereinafter.
The bottom of the valve stem 22 is in the form
of spaced posts 27 providing passageways or ports 28 therebetween
which lead into the interior of the valve stem. The bottom
ends of these posts are rigidly secured to a circular valve
disc 29. The disc is provided with an annular sealing rib
or ring 30 which normally penetrates into the seal 26 to
provide a seal between the interior lOb of the container
and the interior of the stem 22. The sealing ring 30 is
located between the center of the valve head and its periphery.
The raised edge 31 is provided with a number of notches
33 to facilitate flow of product above the ring 30 when
the valve is opened, the edge 31 then functioning principally
as the fulcrum and as a spacer.
It will be evident from Fig. 3 that upon tilting
of the stem 22 in any direction, the disc 29 will fulcrum
about its perimeter and particularly at the raised edge
31 at a considerable distance from the longitudinal axis
of the stem, so that (as is shown at 32 in Fig. 3), a large
opening is made available for the discharge of the product
from the interior lOb and into the stem 22.
Upon the tilting of the stem 22, the portion
of the body 23 of the valve located in the direction of
tilt is compressed, so that upon release of the stem, the
latter is returned to its normal vertical position. When
this occurs, the valve head 29 is returned into its closed
condition in which the sealing ridge 30 is pressed into
the seat 26. In the open condition of valve head 29, the
product flows into the passageway 32 through which it bypasses
the seal 30, where part of such seal remains in engage~ent
with the seat.
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It will be evident that when the stem 22 is tilted,
its bottom and posts 27 tilt the valve head 29 downwardly,
so that the product is able to pass between the raised
edge 31 and the bend 34 in the valve cup. The resilience
of the vertical portion 23 of the valve body enables the
valve head to return to the closed, sealing position when
the stem is released~
The modiication if Fig. 4 facilitates the side
discharge of the product. In this embodiment, the valve
stem fits at its upper end into a sleeve 37 forming part
of a laterally directed nozzle 35 which is provided with
a downwardly extending hood 36 serving to shield the valve.
The sleeve 37 presents a shoulder 38 against which stem
22 abuts, an annular groove being provided in the portion
37 for receiving an o-ring 39 of rubber or the like, to
seal the valve stem at such point. In other respects~
parts corresponding to the valve parts shown in Figs.
2 and 3 are similarly numbered, and function in the same
way.
It will be noted that, as in Figs. 2 and 3, the
raised edge 31 of the disc abuts against a downwardly
extending portion of the valve cup to prevent side movement
of the valve head upon tilting of the stem.
As is shown in Fig. 4, by reason of the fact
that the hinge of the disc 29 is disposed at a rather
large distance from the central axis of the valve stem,
a small degree of tilt of the stem results in quite a
large opening of the valve about its raised edge, thereby
affording the valve a large flow capacity.
An even larger path for the produc~ is provided
for a given angle of tilt in the modification of Fig.
5, wherein the fulcruming ring on the periphery of the
valve head extends considerably above the bottom surface
of the seat, and in the tilting action of the head engages
a portion of the valve cup beyond the periphery of the
valve seat, thereby increasing the radii of tilt both
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of the sealing ring and of the fulcruming ring.
As shown in Fig. 5, the parts corresponding to
those shown in Pigs. 2, 3 and 4 are indicated by the same
numerals but with the letter "a" attached.
The principal differences over the structures
of Figs. 2, 3 and 4 reside in the greater height of the
fulcruming ring 31a than the sealing ring 30a, the top
of the ring 31a being also considerably higher than the
bottom surface of the valve seat 26a, and in the greater
radius of tilt of the valve head.
As in the other figures, the sealing ring 30a
spaces the top surface of the valve head 29a from the
bottom surface of the valve seat 26a, which allows the
ports 28a to extend for a considerable distance below
the bottom of the valve seat.
The fulcrum ring 31a extends ts a shoulder l9b
of the valve cup, it being immaterial whether the ring
exercises a sealing function against the valve cup or
not. However, the shoulder l9b serves to center the valve
head and prevents lateral displacement thereof on tilting
of the valve stem 22a.
Upon tilting of the stem 22a in any direction,
the ring 31a will fulcrum against the shoulder l9b and
will effect a relatively large opening movement in the
region of the diagonally opposite point of the ring 31a
fTom its fulcrum by reason of the larger diameter of the
valve head than its seat and the location of the fulcrum
above the seat; so much so, that all of the sealing ring
30a is quickly separated from the valve seat on tilting
of the stem 22a, and the product has access to all the
ports 28a throughout the full 360, with resultant low
resistance to flow through the valve
As in the other embodiments, the spacing of the
top surface of the valve head from the bottom surface
of the valve seat enables larger ports 28a to be easily provided
at the bottom of the stem, i.e., they can be of increased
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height and hence af~ord increased flow cross-sectional
area.
Fig. 6 shows a pressurized container in which
the bottom wall is not in the form of a separate member,
crimped or double-seamed to the bottom edge of the container
side wall or shell, but is constructed in the manner of
a beer can in which the bottom is integral with the side
wall of the container. However, the bottom lla is provided
with a charging port 16 as in Fig. 1, for charging the
propellant under pressure, after which the port is sealed
with the usual plug 17.
The valves above described have a much greater
rate of discharge of viscous materials of 10,000 cps and
above at the reduced pressures than the known Clayton valve
operating with a container charged at the same reduced
pressure with the same materials. Thus, a Clayton valve
employed with a pressurized container partly filled with
a cheese preparation having a viscosity of about 300,000
cps, the valve having three openings at the bottom of the
stem, each of about 0.09 inch in diameter delivered at
20 psig, a flow rate of only 0.2 g. per second, which is
not acceptable for cheese.
The valves described herein and likewise provided
with three ports at the same location in the vertical stem
as in the Clayton valve, yielded a flow rate for the same
cheese preparation of 0.8 g. per seconcl at 20 psig, which
is an acceptable rate.
The considerably lower cost of pressurized valve
packages of the invention has been stated hereinabo~e.
Specifically, in the case of toothpaste tubes,
which at present are non-pressure packages, the largest
practical size is 8 oz. and costs 10 - 11 cents (for the
collapsible tube). In the quantities used by toothpaste
manufacturers, my improved pressure pack can be sold at
about the same price. Larger economy size toothpaste tubes
are not marketed because they are too cumbersome to handle.
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1092069
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A low pressure barrier pack which will hold 12 oz. of
toothpaste can be more easily handled and will cost 13 -
14 cents, which is about 1 125 cents/oz. This means
that 12 oz. of toothpaste can be sold (including paste)
for substantially less per oz. than collapsible 8 oz.
tubes.
Similarly, significant economies will be obtained
in the pressurized packaging of other fluent materials
of viscosities of 10,000 cps and above, such as cheese,
spreads, greases, lubricants, hair pomades, and the like.
In general, charging pressures of 10 to 15 psig will be
adequate to yield satisactory rates of discharge or
the viscous materials provided that a high capacity discharge
valve, such as above described, is employed.
The economic advantage of plastic containers
with a 0.02 inch wall tas permitted by the present invention),
as compared to the known 0.06 inch wall, is illustrated
by the following:
Polyesters and acetals sell for about 80 cents/lb.,
and a two fluid oz. plastic container weighs about one
oz. for ~ 0.06 inch wall and 0.33 oz. for the 0.02 inch
wall which is adequate in accordance with the invention,
a saving of 0.67 oz. for 3.3 cents/unit.
Examples of plastics and their tensile strengths,
as w~ll as the wall thicXnesses which will insure against
bursting in containers having an outside diameter of two
inches at different pressures, are listed in the following
table:
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Plastic Type Tensile Wall Thickness -for 2"0.D. Cans in inches
Strength For 30 psi For 100~ For Z00
psi Safety Safety
Fac~or ~actor
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Polyethylene 2J500 .012 .024 .036
Polypropylene
Acrylonitrile-
Butadiene-
Styrene
.
10 Polyesters 5,000 ,006 .012 ,018
Acrylics
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Nylon 10,000 .003 .006 .009
Polyesters
Polycar-
bonates
Acetals
Reinforced
Plastics
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Wall thickness for 1" O.D. cans are half of the above and for
other O.D.'s in proportion.
The table indicates minimum thicknesses and shows
only relative strengths, and not necessarily the thicknesses
that will be used practically.
There is considerable overlap of plastic strengths
and the above is only a guide.
Currently available plastic barrier containers
have wall thicknesses in the range of about 0.100 or more
for the lower strength plastics and about 0.060 for the
strongest ones. Some of the wall thicknesses in the above
table are too thin for practical use, but they can be increased
to within a practical range while still remaining below
0.100 inch and 0.060 inch.
The following propellants in various admixtures
can be employed in my improved pressurized packages, the
proportion of liquid propellants being limited in the amounts
and for the reasons set forth hereinabove.
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EXAMPLES OF PROPELLANTS
Pressure r~ e 6-30 psig. Propellants and gases and mixtures of
gases and propellants, but not limited
to the following:
I. For the 30 ~ range:
40~ propellant 12, 60~ propellant 11
25~ propellant 12, 75% propellant 114
20% propellant 115, 80~ propellant 114
Mixtures of propellants 22 with 113 and/or 114 and/or 21
Propellant 318
Hydrocarbon blends such as Butanes and Propanes with
low pressure hydrocarbons such as Pentanes, i.e., both
the normal hydrocarbons and their isomers
Air~ nitrogen, carbon dioxide, any other inert gas at 30 psig
II. For the 6 psig range:
12% propellant 12, 92% propellant 11
20% propellant 12, 80% propellant 113
90% propellant 114, 10% propellant 113
Propellant 21
Hydrocarbon blends of Pentanes with high pressure hydro-
carbons such as Butanes and Propanes, i.e., both normal
hydrocarbons and their isomers
Air, nitrogen, carbon dioxide, any other inert gas at 6 psig
For intermediate pressure ranges, different percentage mix-
tures of the above propellants will be used.
The above-named propellants and the proportions of
mixtures of propell~nts for obtaining the specified pressures
were taken from the well known DuPont chart, from which
the proportions for a 40 psig charging pressure, as well
as for intermediate pressures between 6 and 40 psig can
be readily obtained.
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Propellant 11 is Trichloromonfluoromethane
" 12 is Dichlorodifluoromethane
21 is Dichloromonofluoromethane
" 22 is Chlorodifluoromethane
" 114 is ~ichlorotetrafluoromethane
" 318 is Octafluorocyclobutane
n 315 is Chloropentafluoroethane
" 113 is Trichlorotrifluoroethane
The use of propellants other than air, nitrogen,
or carbon dioxide is minimized in the described system,
and where used will be used in smaller quantities,
As indicated above, the propellant can be either
a gas at a charging pressure of 6 to 40 psig, or a volatile
liquid at a charging pressure of 6 to 24 psig, or a mixture
of a gas at the just mentioned pressure with a liquid propellant,
the liquid in any case being in the limited amount which
will all be evaporated to the vapor state before the temperature
reaches 130 F.
In the filling of the container, there is provided
the cylindrical shell which is open at the top and has
a bottom wall which is either integral with the shell or
is secured thereto in gas-tight manner. The bottom wall
contains a charging po~t while the shell is provided with
the barrier, preferably in the form of a hollow piston
open at its bottom and occupying about one-third of the
container interior. The product to be dispensed is then
introduced through the open upper end, and the valve assembly
is secured to the shell in leak-proof manner. The propellant
is now charged into the piston through the port in the
bottom wall, after which the port is plugged or otherwise
sealed.
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