Note: Descriptions are shown in the official language in which they were submitted.
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Valve unit for gas container with a pressure-indicating or autonomy-indicating
device near the
top
The invention relates to a valve unit for distributing gas, with or without an
integrated
regulator system, which is intended to equip a gas container or the like and
makes it possible to
reduce the risk of errors in reading the pressure in particular, by virtue of
greater flexibility
regarding the positioning of the elements subjected to high pressure, and to a
gas distribution
assembly comprising a gas cylinder, particularly a medical gas cylinder, and
such a valve unit
fixed to the gas cylinder and preferably with a protective cowling arranged
around the valve unit
in order to protect it from knocks and from dirt.
Industrial and medical gases are commonly packaged at high pressure in gas
containers,
typically gas cylinders, equipped with a valve unit, with or without
integrated regulator, namely
a simple valve of the open/closed type or a valve with an integrated
regulator, also referred to
as an integrated valve regulator or IVR, that allows the flow rate and
pressure of the delivered
gas to be controlled.
In order to protect this valve unit, it is common practice to arrange around
said valve
unit a protective cowling that forms a protective shell around the body of the
valve. Such a
cowling is commonly referred to as a "bonnet". Cowlings of this type are
notably described in
documents EP-A-629812, DE-A-10057469, US-A-2004/020793 and EP-A-2586481.
Conventionally, the gases are packaged in the gas containers, typically gas
cylinders, at
high pressure, which means to say typically at pressures higher than 100 bar
absolute, generally
between 200 and 350 bar abs, or even higher.
The high-pressure gas leaving the container therefore has to be expanded
before it can
be used, which means to say that its pressure needs to be regulated down to a
lower usage
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pressure, referred to as low pressure, for example a pressure lower than 20
bar abs, or even often
lower than 10 bar abs.
The gas can be expanded either directly in the valve unit itself, when this is
an integrated
valve regulator unit, also referred to as an IVR unit, or downstream of the
valve unit using a gas
expansion device.
In ail instances, in order to measure and control the pressure of the gas
contained in the
cylinder to which the valve unit is fixed, whether this unit be of the IVR
unit type or not, use is
generally made of a pressure indicating device, such as a pressure gage, the
pressure tapping of
which is in fluidic communication with the gas passage passing through the
valve unit and
carrying the high-pressure gas coming from the cylinder.
Given that the high-pressure gas enters the valve unit via its bottom part,
which means
to says its lower half, which is fixed to the container and which bears the
gas inlet orifice of the
valve unit, the pressure indicating device, typically a pressure gage, is also
generally arranged
at the bottom part of the valve unit, which means to say as close as possible
to the high-pressure
inlet into the valve body. This also meets technical requirements connected
with the dimensions
of the valve unit.
Similarly, it is also possible to resort to a gas autonomy indicating device
to determine
the usage time that corresponds to the quantity of gas remaining in the gas
container equipped
with the valve unit.
Now, the need for this gas pressure or autonomy indicating device to be
positioned at
the bottom part of the valve unit means that it is often difficult or awkward
to read the gas
autonomy or pressure value indicated by same, thereby leading to reading
errors or the need for
the user to adopt a certain position in relation to the cylinder in order to
be able to correctly read
the autonomy or pressure value given by the autonomy or pressure indicating
device.
Document EP-A-2116332 itself teaches a portable device for supplying CO2 to a
pneumatic tool. It comprises a gas cylinder equipped with a valve unit of the
integrated valve
regulator (IVR) type, protected by a protective cowling. The internai
architecture of the IVR is
conventional because it comprises a low-pressure internai chamber situated
downstream of the
site at which the gas is expanded, where a pressure tapping is taken. A
pressure gage situated at
the top of the IVR therefore makes it possible to know the pressure after
expansion but not the
pressure prior to expansion, namely the pressure of the high-pressure gas
leaving the cylinder.
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In the light of that, the problem that arises is that of making it more
comfortable and/or
easier to read the gas autonomy or pressure indicating device, preferably a
pressure gage, with
which a gas distribution valve unit, typically for a cylinder or another gas
container, is equipped,
while avoiding the aforementioned drawbacks, which means to say of proposing a
valve unit of
improved design.
The solution of the invention is therefore a gas distribution valve unit
comprising:
- a valve body comprising a lower part comprising a fixing system allowing
the valve
unit to be fixed to a gas container, and an upper part surmounting the lower
part, the lower part
of the valve body comprising a gas inlet orifice via which a gas can enter the
valve body,
- at least one gas outlet orifice via which the gas can reemerge from the
valve body,
- a first internai gas passage fluidically connecting the gas inlet orifice
to the gas outlet
orifice, and
- a gas autonomy or pressure indicating device fixed to the valve body,
such as a pressure
gage,
characterized in that:
- the valve body comprises a second internai gas passage fluidically
connected to the
first internai gas passage so that the gas pressure applied in said second
internai gas passage is
equal strictly equal or approximately equal) to that applied in the first
internai gas passage
upstream of the site of fluidic connection of the first and second internai
gas passages, and
- the gas autonomy or pressure indicating device is fixed to the valve body
at its upper
end and comprises a pressure tapping in fluidic communication with the second
internai gas
passage so as to measure the pressure of the gas within said second internai
gas passage, namely
the pressure of the high-pressure gas present in the second internai gas
passage.
In general, a valve unit according to the present invention offers numerous
advantages,
aside from the comfort with which the user can read the pressure because of
the possibility of
positioning the autonomy or pressure indicating device at the top of the valve
unit, it notably
making it possible to provide one or more high-pressure gas outlets on top of
the valve unit,
which means to say on the opposite side of any expansion system present, from
the gas source
and also of improving the overall ergonomics of the valve unit, something
which also bas a
tendency to reduce the risks of incorrect reading of a pressure in particular,
thanks to increased
flexibility in the positioning of the elements subjected to high pressure,
namely the pressure
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indicating device, such as a pressure gage, or an autonomy indicating device,
but also other
elements such as pressure sensors, rupture disks, etc.
Depending on the scenario, the valve unit according to the invention may
comprise one
or more of the following technical features:
- it comprises a gas passage control system arranged on the first internai
gas passage and
a control member operable by a user and collaborating with the gas passage
control system to
control the passage of gas in the first internai gas passage, in the direction
running from the gas
inlet orifice to the gas outlet orifice, namely for adjusting the flow rate of
the gas delivered.
- the device indicating the content of the cylinder is a pressure indicator
- the device indicating the content of the cylinder is a pressure gage.
- the device indicating the content of the cylinder is a gas autonomy
indicator.
- the device indicating the content of the cylinder is a di ai-typedevice
or a digital device
indicating an estimate of how long the gas coffesponding to the quantity of
gas remaining in the
cylinder is expected to last.
- the device indicating the content of the cylinder is preferably an
electronic device
which calculates and displays a gas autonomy expressed in time units.
- the valve body comprises a gas expansion system arranged between the site
of fluidic
connection of the first and second internai gas passages and the gas outlet
orifice. According to
this embodiment, it is therefore an integrated valve regulator or IVR valve.
- the axis BB of the pressure indicating device makes, with the axis AA of
the valve
body, an angle a comprised between 0 and 90 , preferably between 100 and 80 ,
more preferably
between 25 and 70 .
- the gas outlet orifice is borne by a gas outlet coupling situated between
the upper and
lower parts of the valve body for example.
- the expansion system comprises a high-pressure chamber, a valve shutter
and a valve
seat, and a low-pressure chamber.
- the system for controlling the passage of gas comprises a mobile element
bearing
calibrated orifices of increasing dimensions corresponding to increasing
values of gas flow rate.
- the mobile element of the system for controlling the passage of gas is a
rotary disk.
This rotary disk is pierced with calibrated orifices.
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- the rotary handwheel collaborates rotationally with the mobile element of
the system
for controlling the passage of gas so as to control the flow rate of gas
delivered by the valve
unit.
- the portion of the first internai gas passage, situated between the gas
inlet orifice and
the site of fluid connection of the first and second internai gas passages,
and the second internai
gas passage are configured, which means to say able to and designed to, convey
gas at high
pressure.
- the pressure indicating device is a dial-type pressure gage or a pressure
gage with a
digital display, , also referred to as an "electronic" or "digital" pressure
gage.
- the pressure tapping of the gas autonomy or pressure indicating device is
in fluidic
communication with the second internai gas passage via a connecting passage
formed in the
body of the valve.
- the control member operable by a user is a rotary handwheel or a pivoting
lever,
preferably a rotary handwheel.
- the rotary handwheel is arranged coaxial ly and around the gas outlet
connector bearing
the gas outlet orifice.
- the site of fluidic connection comprises the high-pressure chamber of the
expansion
system. This high-pressure chamber therefore has gas passing through it at
high pressure, which
means to say that the first passage of gas conveys the high-pressure gas as
far as said high-
pressure chamber and the second passage of gas discharges some of the high-
pressure gas from
said chamber and conveys it to the pressure tapping of the gas autonomy or
pressure indicating
device so that the pressure of said gas can be measured. In other words, the
site of fluidic
connection (i.e. the connection site) is situated upstream of the expansion
system, and therefore
of the expansion itself, the high-pressure chamber coinciding with the site of
fluidic connection
or being connected thereto.
- the body of the valve is made of copper alloy, of brass, of steel or of
stainless steel, or
of aluminum alloy.
- the fixing system that allows the lower part of the valve body to be
fixed to a gas
container comprises a screw thread formed on the externat periphery of an
enlargement of
cylindrical or conical shape located in the region of the lower part of the
valve body. The screw
thread borne by the cylindrical or conical enlargement can be fixed by screw-
fastening into a
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mating screw thread/tapped thread formed at the outlet orifice of the gas
container, particularly
on the neck of a gas cylinder.
- the body of the valve further comprises a filling connection comprising a
filling orifice,
preferably with an interna! nonreturn valve, allowing high-pressure gas to be
introduced into the
gas container equipped with said valve body, for example when it is empty,
namely when it does
not contain or no longer contains gas, or is near-empty, which means to say
that it still contains
a little gas.
The invention also relates to a gas distribution assembly comprising a gas
container,
such as a gas cylinder, and a valve unit fixed to said gas container, said
valve unit being as
indicated hereinabove.
Depending on the circumstance, the assembly of the invention may comprise one
or
more of the following technical features:
- the gas container is a gas cylinder, also referred to as a carboy, a gas
tank or a bottle.
- a protective cowling is arranged around said valve unit, the protective
cowling
comprising an opening formed level with the upper part of the protective
cowling and within
which the pressure-indicating device, typically a pressure gage, or a gas
autonomy indicating
device, becomes housed, which means to say that the opening is formed through
the wall of the
cowling.
- the protective cowling comprises a planar surface at its upper part, the
opening
comprising the gas autonomy or pressure indicating device being formed in said
planar surface.
- the planar surface forms a face that is oblique with respect to the
vertical axis of the
cowling.
- the cowling is made of a polymer material, for example of plastic, or
composite or of
metal or metal alloy, for example steel, cast iron, aluminum or an aluminum
alloy.
- the cowling is made of plastic such as PVC, PE, PET, PP, PMMA, PU, PA,
etc. It
should be noted that the plastic may be filled or reinforced, which means to
say may contain
added fibers for example.
- the protective cowling comprises a carry handle, preferably a carry
handle connected
to the cowling via one or more support uprights.
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- the carry handle is arranged on the cowling in such a way that the gas
autonomy or
pressure indicating device is positioned substantially between the carry
handle and the valve
unit bearing said gas autonomy or pressure indicating device.
- the protective cowling further comprises a hang-up device, preferably a
pivoting hang-
up device, so that the assembly cati be hung on a support, particularly the
rung of a bed, to a
stretcher, etc.
- the carry handle and/or the support upright or uprights are formed from a
ri gid material
selected from polymers and metals or metal alloys.
- the carry handle is longiforrn overall. Typically, its length is
comprised between 5 and
20 cm, preferably between 6 and 15 cm.
- the carry handle surmounts the cowling body.
- the carry handle is horizontal or near-horizontal and is perpendicular to
the vertical axis
of the cowling (i.e. the axis of the cowling corresponds to the axis of the
valve and/or of the
cylinder).
- the gas cylinder has a size of between 10 and 150 cm.
- the gas cylinder contains from 0.5 to 20 liters (water-equivalent
capacity).
- the gas cylinder has a hollow cylindrical body and comprises a neck
bearing a gas outlet
orifice to which the valve unit is fixed, preferably by screwing.
- the gas cylinder contains a gas or gaseous mixture, preferably a gas or
gaseous mixture
that meets the specifications of the medical domain (pharmacopeia).
- the gas cylinder contains a gas or gaseous mixture selected from oxygen,
air, an N20/02
mixture, an He/02 mixture, an NO/nitrogen mixture or any other gas or gaseous
mixture.
- the cylinder is made of steel, of aluminum alloy, of composite material
or a
combination of several of these materials.
- the cylinder contains gas at a pressure ranging up to around 350 bar.
The invention also relates to the use of a valve unit according to the
invention or of a gas
distribution assembly according to the invention to distribute a gas or
gaseous mixture,
preferably a medical gas or gaseous mixture.
For preference, the gas or the gaseous mixture is chosen from oxygen, air,
N20/02,
He/02, NO/nitrogen.
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The invention will now be better understood from the following detailed
description,
given by way of nonlimiting illustration, with reference to the attached
figures among which:
- figure 1 depicts an embodiment of a cylinder/valve unit/cowling assembly
according
to the invention, and
- figures 2 and 3 depict views in cross section of the valve unit according
to the invention
of the assembly of figure 1,
- figure 4 schematically depicts the principle of operation of the valve
unit according to
the invention of the assembly of figure 1, and
- figure 5 depicts a view in cross section of the valve unit of figure 2
according to the
invention, arranged inside a protective cowling.
Figure 1 shows one embodiment of a rigid protective cowling 21, also commonly
referred to as a "bonnet", arranged around a valve unit 1 according to the
invention (visible in
figure 5), namely a valve unit that may or may flot be an integrated valve
regulator unit, itself
fixed to the neck of a gas cylinder 20, said protective cowling 21 being
provided with a carry
handle 25 according to the present invention.
The gas cylinder 20 typically bas a cylindrical body made of steel and a size
of between
and 150 cm, and a capacity of 0.5 to 20 liters (in water equivalent).
The protective cowling 21 allows the valve unit 1 to be protected against
knocks whether
the valve unit 1 is of the IVR type with integrated regulator or of the type
without an integrated
regulator.
Fixing around the valve unit 1 to the neck of the gas cylinder 20 is performed
by
screwing, using enlargement screw threads borne by the internai surface of the
neck of the
cylinder 20, on the one hand, and by the extemal surface of an enlargement 12
of substantially
cylindrical or conical shape, situated at the base of the valve body 1 and
bearing the gas inlet
orifice 2, as visible in figures 2 and 5, on the other.
More specifically, the protective cowling 1 comprises a cowling body 2 forming
a
protective shell around an internai volume sized to accept the valve unit 1,
and a carry handle
25 designed to be held by a user in their hand.
The body of the cowling 21 is typically made of a material of the polymer
and/or metal
type, preferably from a plastic such as PVC, PE, PET, PP, PMMA, PU, PA, etc.
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The carry handle 25 is made from a rigid material such as a polymer or a metal
or a metal
alloy and is borne by one or more support uprights 24 that mechanically
connect the cowling
body to the carry handle 25. The carry handle 25 is generally arranged
horizontally, which
means to say at right angles or near-right angles to the vertical axis of the
cylinder 20 and of the
cowling 21. The carry handle 25 has a longilinear shape, whether it be
rectilinear or curved,
typically a length shorter than 20 cm, typically from 6 to 15 cm.
One or more support uprights 24 are fixed to the carry handle 25 in such a way
as to
al low a user easily to carry the assembly comprising the bonnet 21, the valve
1 and the cylinder
20 using said carry handle 25.
The support uprights 24 may be formed from a plastic, like the body of the
cowling 21,
but may also be made of aluminum alloy or any other metallic material. They
may be fixed to
the handle 25 by screwing or welding, for example, or formed as one piece
therewith.
The protective cowling 21 also has openings providing access to the valve unit
1 situated
inside the internai volume of the cowling body.
In particular, a first opening 22 is created at the upper part 21a, also
referred to as the
top part, of the protective cowling 21, within which opening the pressure
indicating device 7,
namely in this instance a pressure gage, either of the dial type or of the
electronic type, can
become housed. The lower part 21b, also referred to as the bottom part, of the
cowling 21 is
positioned around at least part of the neck of the cylinder 20, as visible in
figure 1.
More specifically, the protective cowling 21 comprises a planar surface 26 at
its upper
part 21a, namely at the top of the cowling, inside which the first opening 22
is created. The
planar surface 26 in fact constit-utes a face that is oblique with respect to
the axis CC of the
cylinder 20. For preference, the planar surface 26 is perpendicular to die
axis 1313 of the pressure
indicating device 7, as outlined in figure 1. Typically, the axes CC of the
cylinder 20 and AA of
the valve unit 1 are coincident, which means to say coaxial.
Furthermore, the protective cowling 21 comprises a second opening 27 formed on
the
façade or front face of the protective cowling, and in which the rotary
handwheel 5 controlling
the flow rate of gas passing through the valve unit 1 becomes housed, as
explained hereinafter
in conjunction with figures 2 and 3.
In the embodiment of figure 1, the rotary handwheel 5 is arranged around the
gas outlet
connection 13 bearing the gas outlet orifice 6 used to withdraw the gas stored
in the cylinder 20.
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However, the rotary handwheel 5 could be arranged differently, which means to
say can
potentially flot be coaxial with the gas outlet connection 13.
Furthermore, the valve unit 1 also comprises a filling connection 17 with an
internai
check valve 18 (cf figures 2 and 5) which filling connection 17 is used to
introduce pressurized
gas into the cylinder 20 when the cylinder is empty or near-empty.
Furthermore, in order to allow the cylinder/valve unit/cowling assembly to be
hung from
or secured to a support, such as a bar of a hospital bed or stretcher, the
protective cowling 21
comprises, on its rear face side, a pivoting hang-up device 28, able to pivot
between a completely
folded "rest" position (outlined in figure 1), which means to say the position
adopted by the
hang-up device 28 when stored in contact or near-contact with the body of the
cowling 21, and
a fully deployed position referred to as the "hang-up" position (flot
depicted), which means to
say the position adopted by the hang-up device 28 when it is fully extracted
and can be hung
from a support, such as a bed rung or the like.
In ail cases, the pressure indicating device 7 is fixed to the body 1 of the
valve unit which
is situated within the internai volume of the cowling 21, as visible in
figures 2 and 3. Arranging
the pressure indicating device 7 in this way at the top on the valve unit 1
and on the façade of
the cowling 21 makes it considerably casier to read the pressure delivered by
the pressure
indicating device 7, and avoids reading errors.
For preference, as illustrated in figure 2, the axis BB of the pressure gage 7
and the axis
AA of the valve unit 1 form an angle a comprised between 0 and 90 , notably
between 100 and
80 , preferably between 25 and 70 , and typically of the order of 35 to 55 .
As detailed in figures 2 and 3, the gas distribution valve unit of the
invention comprises
a valve body 1 schematically comprising an upper part la forming the top of
the valve unit I,
and a lower part lb forming the base of the valve unit I. The upper part la
therefore surmounts
the lower part or base lb of the unit 1.
The lower part lb of the valve unit 1 comprises the fixing system 12a, such as
a screw
thread, allowing the valve unit 1 to be fixed to the cylinder 20 as already
explained, and the gas
inlet orifice 2 via which a pressurized gas coming from the cylinder 20 can
enter the valve body
1 and then be conveyed therein as far as the gas outlet orifice 6 borne by the
outlet connection
13 via which the gas can re-emerge from the valve body 1.
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As already explained, the lower part lb of the valve body 1 is configured to
be attached
by screw fastening. For that, the lower part lb comprises an enlargement 12 of
the body
projecting downwards, of cylindrical or conical overall shape and bearing a
screw thread I2a
on its externat surface able to collaborate in screwing with a complementary
screw thread or
tapped thread formed in the neck of the cylinder 20.
A first internai gas passage 3 fluidically connects the gas inlet orifice 2 to
the gas outlet
orifice 6 borne by the outlet connection 13. This first internai gas passage 3
therefore passes
axially through the enlargement 12 of the body 1 of cylindrical or conical
overall shape, as
shown in figure 1, said enlargement 12 also bearing the gas inlet orifice 2.
Moreover, the valve unit 1 also comprises a system 23 for controlling the
passage or
flow rate of gas collaborating with the control member 5, namely here a rotary
handwheel
operable by the user, to control the passage of gas in the first internai gas
passage 3, which
means to say to allow or, conversely, prevent, any circulation of the gas in
said passage 3 in the
direction running from the gas inlet orifice 2 to the gas outlet orifice 6
borne by the outlet
connection 13.
The gas flow rate control system 23 comprises an element pierced with
calibrated holes,
the handwheel, as circumstances dictate, either causing the calibrated hole
corresponding to the
desired flow rate to collaborate with a fixed passage orifice or causing a
mobile passage orifice
to collaborate with the calibrated hole corresponding to the desired flow
rate. Such an
arrangement is commonplace and known to those skilled in the art.
Thus, according to the embodiment depicted here, the element pierced with
calibrated
orifices is a mobile metal disk through which calibrated orifices pass. The
orifices have different
calibers, i.e. increasing calibers, each caliber corresponding to a given flow
rate value. This disk
is capable of rotational movement and is tumed by the handwheel 5.
There are no valves in the passage control system according to the embodiment
set out
in the figures. However, according to other more conventional designs
incorporating an
opened/closed function in the high-pressure part of the valve unit, it is
possible to provide for
the handwheel 5 also to perform this open/close function. In this case,
incorporating an
opening/closing valve that seals onto a seat when elosed, may prove to be
necessary.
Furthermore, the valve unit also incorporates, as illustrated in figure 2, a
translationally
mobile valve shutter 4, one or more seals 15, such as o rings, and at least
one retum spring 14.
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The valve 4 is a residual-pressure valve intended to maintain constantly a
positive pressure in
the cylinder. This valve 4 operates autonomously, without action on the
handwheel.
According to the present invention and as illustrated in figures 2 and 5, the
body 1 of the
valve comprises a second internai gas passage 11 fluidically connected to the
first internai gas
passage 3 at a site of connection or fluidic connection 10.
The second internai gas passage 11 therefore forms a fork or brandi off the
first internai
gas passage 3.
The second internai gas passage 11 and at least the portion of the first
internai gas
passage 3 comprised between the inlet orifice 2 and the fluidic junction site
10 carry gas at high
pressure coming directly from the gas cylinder 20. These passages 11, 3 are
therefore subjected
to high pressure, typically to pressures ranging up to about 350 bar absolute.
Furthermore, the pressure indicating device, in this instance a pressure gage
7, which is
fixed to the valve body 1 near the upper end la thereof, comprises a pressure
tapping 8, for
example a duct or the like, in fluidic communication with the second internai
gas passage 11 so
as to measure the gas pressure within said second internai gas passage I 1.
The pressure tapping 8 of the pressure indicating device 7 may be fluidicaily
connected
to the second internai gas passage 11 indirectly, for example via a connecting
passage 16 fornied
in the body 1 of the valve and connecting the pressure tapping 8 of the
pressure indicating device
7 to the second internai gas passage 11, as illustrated in figures 2, 3 and 5.
In the embodiment of figures 2, 3 and 5, the valve unit is of the IVR type,
namely
comprises a regulator system 9 for expanding the gas which is positioned
between the site of
fluidic connection 10 of the first and second internai gas passages 3, 11 and
the gas outlet orifice
6 so as to achieve a reduction in the pressure of the high-pressure gas coming
from the cylinder
20 down to a lower pressure value, for example a passage from a high pressure
above 100 bar
to a low pressure below 20 bar abs.
To this end, in the conventional way, an expansion system 9 is provided that
comprises
an expansion valve shutter and a valve seat. The final pressure may be of
adjustable or fixed
value.
As visible in figures 2, 3 and 5, the gas circulating along the second
internai gas passage
11 is flot subjected to expansion within the expansion system 9 because the
site of connection
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or of fluidic connection 10 between the first and second gas passages 3, 11 is
situated upstream
of the expansion system 9.
The site of connection or of fluidic connection 10 is typically the chamber
known as the
high-pressure chamber of the expansion system 9, which high-pressure chamber
then has
passing through it the high-pressure gas which is conveyed to it by the first
gas passage 3. Some
of the high-pressure gas is then discharged via the second gas passage 11
which then carnes it
as far as the pressure tapping 8 of the pressure gage 7 (or of an autonomy
measurement device)
so as to allow the pressure of said gas to be measured. This design is of key
importance to the
context of the present invention.
Figure 3 gives a better view of the expansion system 9 and the high-pressure
chamber
10. More specifically, aside from the pressure tapping 8 and the pressure gage
7, it is also
possible to sec the expansion valve of elongate shape, i.e. with a stem, the
valve seat, an
expansion spring and an expansion piston which determines the position of the
expansion valve
according to the load of the expansion spring, the high pressure and the low
pressure.
Ail of these elements are also visible in figure 4 which outlines the
principle of operation
of the valve unit according to the invention.
Tt is also possible to sec there that the valve unit also comprises an
internai filter 19 and,
arranged downstream of the expansion system 9, a low-pressure gas outlet with
isolation valve
30.
An assembly according to the invention is particularly well suited for use in
a medical
environment, particularly for distributing any medical gas or gaseous mixture,
particularly of
the oxygen, air, N20/02, He/02, NO/nitrogen or some other type.
