Tap with flow limiter for gas bottles

A tap for a bottle of compressed or liquified gas has fitted therein a flow limiter in the form of a cartridge internally comprising a first, upstream chamber receiving the gas coming from the bottle, a second, downstream chamber opening into a supply line and a calibrated passage connecting the first and second chambers. A flow control assembly comprising a valve associated with a calibrated control element and an expansion chamber is preferably arranged to control the flow between the first and second chambers. The tap has particular utility in bottles for transfer of toxic and/or spontaneously inflammable gases, since it prevents major leaks from such bottles or from supply lines fed therefrom.

BACKGROUND OF THE INVENTION 
The present invention relates to a flow limiter device for the gas bottles 
intended to contain a gas which is compressed or liquified under pressure. 
DESCRIPTION OF THE PRIOR ART 
Bottles are currently utilised in industry which comprise a conventional 
screw-down valve operable, depending on its position, to close or open a 
user circuit. 
Certain gases which are utilized in industry in the compressed state, or 
liquified under pressure in metal bottles provided with a tap, are 
extremely toxic and/or spontaneously inflammable when in contact with the 
air. 
In case of leakage at the utilising plant, products of this nature are not 
without danger to the workforce. They may also cause substantial material 
damage and atmospheric pollution. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to minimise the disastrous 
consequences caused by an escape from the utilising plant of a gas of the 
kind referred to above. 
This object is attained in accordance with the invention by a tap for 
bottles intended to contain a gas which is compressed or liquified under 
pressure, said tap being provided with a flow limiter device formed at 
least two chambers in communication via a calibrated passage, a first and 
so-called upstream chamber receiving the gas coming from the bottle, and 
the other so-called downstream chamber, being in communication with the 
consumer circuit, wherein said flow limiter device is in the form of a 
cartridge which may be installed in hermetic manner within a housing 
wrought within the body of the tap for this purpose. 
In a preferred embodiment of the invention the cartridge is arranged to 
form a third and so-called expansion chamber between the first chamber and 
the calibrated passage, supplied with gas through a valve which is 
associated with calibrated control means and also with a return device. A 
flow limiter device of this kind will be referred to in the following as a 
"limiter-expander", whereas a limiter lacking an expansion chamber is 
referred to as a "simple limiter". 
A cartridge provided with a simple limiter is intended more specifically to 
be associated with a tap for a bottle containing a gas under low pressure, 
whereas a cartridge provided with a limiter-expander is intended more 
particularly as equipment for a tap for a bottle containing a gas under 
high pressure, as will emerge from the following. 
The gas flow available may be limited, at the very source, by means of a 
system of this nature, to the lowest value commensurate with utilisation. 
The flow limiter device is of course devised as a function of the pressure 
of the gas present in the bottle. 
Given that the delivery of the available gas is organised at the very 
source on the one hand, and that on the other hand, this flow has a 
minimum value commensurate with utilisation, it will be grasped that in 
case of a pipe fracture beyond the tap, the leak will be a minimum whereas 
in conventional taps, the gas was free to escape at a speed dependent on 
the leak in the case of an escape between the tap and optional expansion 
means, with all the disadvantages referred to above. 
In one embodiment of the invention, the body of a tap which comprises a tap 
key operating a valve, an end piece for connecting the tap to the bottle, 
and an end piece for connection of the consumer circuit, has formed within 
this latter end piece a housing or recess to receive a cartridge, the 
latter being situated downstream of the said valve. 
In another embodiment, it is the end piece formed on the tap body for its 
removable installation on a bottle which receives a cartridge; the latter 
is then situated in the actual interior of the bottle, upstream of the 
valve associated with the tap key. In another embodiment, the end piece 
formed on the tap body for removable installation of the tap on the bottle 
is extended towards the inside of the bottle by a tubular stub on which is 
secured in any appropriate manner a cartridge carrier socket which, given 
the structure in question, is consequently situated in the very interior 
of the bottle, upstream of the valve associated with the valve key. 
According to a further embodiment of the invention, the cartridge is joined 
to the tap by being screwed into a screw-thread formed in the said recess, 
and it has a front or leading surface arranged to co-operate with a 
sealing gasket previously placed in position in the said recess. 
According to another feature of the invention, the cartridge 
comprises--within its upstream chamber--a valve arranged to be actuated by 
a valve lifter rod formed integrally with calibrated control means, and 
between the upstream chamber and the calibrated opening, an expansion 
chamber in communication with the downstream chamber. 
The taps provided in this manner with a cartridge comprising a simple 
limiter device or a limiter-expanded device, consequently substantially 
improve safety in the distributor circuit. 
As a matter of fact, the breakdown of the distributor circuit, irrespective 
of the nature of the breakdown or whether it is close to or distant from 
the bottle, allows no more than a minute quantity of gas to escape (gas 
delivery at the minimum value commensurate with utilisation), whereas in 
bottles used hitherto, in case of failure of the plant between the 
expander and the bottle, the gas escaped freely whilst the tap key 
remained unused for closure of the circuit. 
Other features and advantages of the invention will emerge moreover from 
the following description taken in conjunction with the accompanying 
drawings wherein preferred embodiments of the invention are illustrated.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 shows a simple flow limiter device comprising a cartridge C. This 
cartridge comprises a barrel 40 wherein are formed at either end of a 
calibrated axial passage 41, a first, upstream chamber 42 to receive a 
filter 43 secured by a retainer ring 44, and a second, downstream chamber 
45, these two chambers being spaced apart on one and the same longitudinal 
axis. 
It is specified that, in this case, the upstream chamber is that which is 
intended to receive the gas comining from the bottle, whereas the 
downstream chamber is that which is intended to feed the gas into the 
consumer circuit. 
The cylindrical body of revolution 40 is screw-threaded at 46 on its 
external surface to allow removable installation of the cartridge in an 
appropriate recess formed for this purpose in a tap body as will emerge in 
the following. Blind holes 47--for example being two diametrical holes 
which are formed in the rear surface of the cartridge, are intended to 
receive the studs of a tool (not illustrated herein) devised for its 
installation on a tap body, a system of this nature being intended to 
prevent any dismantling by an unauthorised person. The blind holes may be 
replaced by a slot, or else by a twin cross-shaped slot. 
The calibrated passage 41 which in the example illustrated in FIG. 1 is 
formed within the mass of the barrel, may also as shown in FIG. 2, be 
formed in a plug 50 inserted in a bore 51 in a force-fit, or interference 
fit. As shown by FIG. 3, it may also be formed in a ring 52 engaged within 
another ring 53 inset in an interference fit in a bore 51 provided in the 
barrel 40 and provided at the rear with a conical surface 54 diverging 
from the inside towards the outside. 
Tapering towards its front surface, the cartridge C comprises a 
frustoconical surface 59 the purpose of which will emerge in the 
following. 
A simple flow limiter of this kind is highly suitable if the pressure 
available within the bottle is moderate and the pressure of application is 
low, for example lower than five bars, and the difference between these 
two pressures is sufficiently small, for example if the value of the 
pressure in the bottle does not exceed 4 to 5 times that of the 
application pressure. 
For a given calibrated passage, the flow variation is effectively and 
substantially proportional to the pressure variation upstream of this 
passage. 
In the case, however, in which the pressure available in the bottle is 
substantial, for example greater than 20 or 30 bars and/or it is desired 
at all costs to restrict the leakage flow to the utilisation flow 
throughout the period of operation of the gas bottle, it is necessary to 
provide the latter with a "limiter-expander" cartridge. 
The cartridge C comprising a "limiter-expander" device shown in FIGS. 4 and 
5 also comprises a cylindrical body of revolution 40 having a front 
section with a frustoconical surface 59. 
Along the axis X--X of the barrel 40, the cartridge comprises a first 
high-pressure (HP) chamber 42 and a second low-pressure (BP) chamber 45. 
The first chamber is delimited by a base 69 comprising a passage 70, and a 
valve seat 71 for a valve 72 kept in position by a spring 73, bearing on a 
filter 43 which for its part is held in position by means of a ring 44. 
The valve 72 comprises a flange 76 having a series of holes 77, for example 
three. 
Between the valve seat 71 and the radial calibrated passage 41, the barrel 
40 comprises an expansion chamber CD which is in communication with the 
second low-pressure chamber 45. The chamber 45 in this case by a passage 
opening in the rear surface of the cartridge C. 
The passage 70 loosely accommodates, a valve lifter rod 83 integral with 
calibrated control means, these means adavntageously comprising a metal 
bellows 84 placed in position in a chamber 85. The bellows 85 has a front 
surface 86 facing towards the expansion chamber CD and a free extremity 
exposed to the action of an adjusting screw 87. A toroidal gasket 88 
assures sealing, whereas the front surface 86 of the metal bellows is 
arranged to co-operate with a bearing surface 89 formed in the base of the 
bore 85. 
Blind longitudinal holes 47 allow the insertion of a matching handling key 
or spanner, whereas the immobilization of the adjusting screw 87 with 
respect to the barrel is advantageously assured for example by means of 
spot welds 91. 
In a manner resembling that of the barrel of the cartridge C in FIG. 1, the 
barrel of the cartridge comprises a screw-thread 46 on its outer surface. 
The metal bellows 84 forms a hermetic volume and acts as an expansion 
spring; the pressure of the gas within the bellows serves the purpose of a 
reference pressure the force of which is added to that of the spring 
formed by the metal bellows 84. 
A cartridge C of this nature may be incorporated in any tap body as will 
become apparent in the following. 
According to a third embodiment shown in FIG. 6, the cartridge C comprises 
a barrel 40 analogous to that shown in FIG. 4, which a first high-pressure 
upstream chamber 42 and a low-pressure downstream chamber; as in the 
embodiments described above, the high-pressure upstream chamber comprises 
a filter 43 secured by a ring 44, a valve 72 exposed to the action of a 
retaining spring 73, a valve seat 71, an expansion chamber CD, a 
calibrated radial passage 41 and an expansion chamber formed by a duct 45. 
The barrel also has blind holes 47 for an appropriate tool, as well as a 
bore 85 wherein is engaged a piston 95 having a peripheral seal 96, 
instead of the aforesaid metal bellows; the front surface 97 of the piston 
is extended towards the upstream high-pressure chamber HP by a valve 
lifter rod 83, slidingly fitted with play in the passage 70 to establish 
an annular space. 
At its rear surface, the piston 95 co-operates with calibrated control 
means for the valve lifter rod which, in the present case, comprise an 
expansion spring 98 whose force may be modulated by means of an adjusting 
screw 99 having an internal terminal part provided with a sealing joint 
100. 
According to a fourth embodiment shown in FIG. 7, the cartridge C comprises 
a barrel 40 analogous overall to the preceding embodiments comprising a 
first high-pressure upstream chamber HP, a second low-pressure downstream 
chamber BP, and an expansion chamber CD; the same reference numerals are 
used again to denote elements already described with reference to the two 
preceding embodiments. 
In this embodiment, the cartridge C comprises calibrated control means 
differing in structure inasmuch as they comprise an internal screw-thread 
102 which receives a hollow screw 103. A spring 105 is inserted in the 
screw 103. One extremity of the spring 105 bears on a diaphragm 106 to 
which is secured the valve lifter rod 83, and the other extremity bears 
against a spacer 107. 
It should be noted that the inner extremity 108 of the hollow screw 103 
co-operates with a gasket 109 designed to assure sealing. The compressive 
forces of the spring 105 may easily be adjusted by placing in position one 
or more spacers 107 of appropriate thickness. 
The aforesaid diaphragm 106 may be of any kind, for example flat, 
corrugated or convex, of metal or other appropriate material. 
One or other of the cartridges C above is appropriate to equip taps of 
different kinds for bottles containing a gas which is compressed or 
liquified under pressure. 
In FIG. 8, a tape comprises a barrel 10 having three end pieces 10A, 10B, 
10C respectively; the end piece 10A or tap shank is intended to be 
connected to the neck of a bottle B shown by broken lines; the end piece 
10B comprises a seat 12 to co-operate with a valve 13 which may be handled 
by means of a tap key 14, whereas the end piece 10C which is substantially 
radial is externally screw-threaded at 15 for the purpose of connecting a 
pipe 16 which may be of any suitable type to the consumer circuit, by 
means of a cap nut 16A and of a gasket 16B. The tap body internally 
comprises a duct 17 extending within the end piece 10A, as far as the 
valve seat 12 and downstream of the said seat, towards the end piece 10C 
via a passage 18. 
According to the invention, the end piece 10C of the tap body 10 is 
provided internally with a tapped recess L to accommodate a cartridge C in 
hermetic manner by means of toroidal seal 58 co-operating with the 
frustoconical surface 59 (FIG. 1). A cartridge of this nature is 
consequently situated downstream of the valve 13 on the trajectory of the 
duct between the inside of the bottle and the consumer circuit. The 
cartridge may comprise a simple limiter device, or a limiter-expander 
device. It may be noted that the aforesaid toroidal seal may be replaced 
by a flat seal, the front section of the cartridge being organised for 
this purpose. 
In the embodiment shown in FIG. 9, the tap body generally indicated by 10 
comrpises as previously, a first end piece 10A intended to be connected to 
the neck of the bottle B. A second end piece 10B is arranged to receive a 
tap key 14 operating a valve 13 with respect to the seat 12, and a third 
end piece 10C is directed at right angles to the preceding end pieces. 
They are arranged for connection of a pipe 16 to any desired apparatus 
(not illustrated), or to an evacuation device or filling device for the 
bottle. 
The tap body also comprises an axial passage 17 and a second passage 18 
formed in the end piece 10C, these two passages being liable to be placed 
in communication or separated depending on the position imparted to the 
valve 13 on its seat 12. 
As illustrated, the first end piece 10A is provided with a tapper recess L 
for reception of a cartridge C. 
It will be observed that, according to this embodiment, the filling of the 
bottle B, or its evacuation, may raise some problems because operations of 
this nature must necessarily be carried out via the cartridge C. For 
filling or evacuation purposes, the pipe 16 is connected to the end piece 
10C, whereupon the valve 13 of the tap key 14 is opened and this valve is 
closed once the operations are completed. 
In FIG. 10, the end piece 10A of the tap body is arranged to receive a tube 
section 26 attached by a weld 25, a socket 28 being attached to the tube 
section, by means of a weld 27, to receive a cartridge C. 
In both embodiments referred to in the foregoing and illustrated by FIGS. 9 
and 10, the cartridge which is placed on the trajectory of the duct 17 is 
situated within the bottle which may give rise to particular limitations 
during application, as has been stated in the foregoing. 
As a matter of fact, it will be appreciated that it is impossible to 
dismantle the cartridge C in the embodiments shown in FIGS. 9 and 10 for 
the purpose of evacuating or filling operations. 
The cartridge C is preferably incorporated in the tap body downstream of 
the valve 13, outside the bottle B as illustrated in FIGS. 8, 11, 12 and 
13. 
In the case of FIG. 8, it is possible and indeed preferable to dismantle 
the cartridge C when a vacuum has to be established or the gas bottle has 
to be filled, so that these operations are not performed under limitations 
which would increase the duration of these operations. 
In FIG. 11, the tap body 10 comprises four cruciformly positioned end 
pieces. The end pieces comprise a first end piece 10A forming a tap shank 
to be screwed into the neck of a bottle B, and a second end piece 10B 
arranged to carry a tap key 14 and having its valve 13 co-operating with a 
seat 12. At right angles to the aforesaid end pieces 10A and 10B, the tap 
body 10 comprises two extensions forming end pieces 10C and 10D situated 
at either side of the valve 13. A duct 32 places the two end pieces 10C 
and 10D in communication, and a duct 33 places the inside of the bottle in 
communication with the duct 32 when the valve 13 is open. A configuration 
of this nature is preferable, since it allows evacuation and scavenging of 
the internal chamber 32 of the tap corresponding to the high-pressure 
chamber 42 (FIG. 1) of the flow limiter. 
One of the end pieces, being the end piece 10D in this case, receives a 
removable plug 34, and the other receives a cartridge C. In this 
embodiment, the plug 34 bears on a sealing joint 35 and may easily be 
removed for evacuating or refilling the bottle B and placed in position 
again thereafter, thus averting any handicap during the said operations. 
In FIG. 12, the body 10 of the tap has a Y-shaped overall layout; the 
branches of the Y form two divergent end pieces 138, 139, each being 
adapted to receive a tap key 14, whereas the single branch of the Y forms 
an end piece 140 which comprises a tap shank to be screwed into the neck 
of a bottle B. Two ducts 141,142, branch off into the end pieces 138,139 
from a single duct 143 in the end piece 140 whose orifice opens inside the 
bottle B. 
The tap body above also comprises two lateral end pieces 144,145 
substantially confronting each other, these being arranged to receive a 
plug 34 in the one case and a cartridge C in the other. 
Upstream of the valve 13A, a passage 146 opens into the end piece 144, and 
downstream of the valve 13B, a passage 147 opens within the end piece 145, 
so that each valve 13A, 13B may be operated separately according to the 
requirements of the filling, evacuation or utilization of the bottle. 
The filling or evacuation of a bottle equipped in this manner is performed 
easily via the ducts 146, 141, 143 after withdrawal of the plug 34 and 
opening of the valve 13A, whereas the ducts 143, 142, 147 are arranged to 
convey the product to the application stage when the plug 34 is in 
position again and the valve 13A is closed, whilst the other valve 13B is 
open. 
In FIG. 13, the tap body 10 is analogous overall to that described with 
reference to FIG. 12, subject to the difference that each of the ducts 
141, 142, closable by means of the valve 13A, 13B of the tap keys 14, 
opens inside the bottle B, one of the end pieces (144) receiving a 
removable plug 34, and the other an optional cartridge C comprising a 
simple limiter device or a limiter-expander device. 
In this embodiment, the filling or evacuating operations on the bottle B 
may be performed once the plug 34 is removed, the valve 13A is opened and 
the valve 13B is closed, whereas during use, it is the valve 13A which is 
closed and the valve 13B which is opened to allow gas to flow via the 
ducts 146, 147 and any cartridge C, and thence to the consumer facility. 
The gas flow supplied by the limiter device formed by the cartridge C 
having a simple limiter is evidently a function of the calibrated passage 
orifice. As for the "limiter-expander" device, its operation may be 
established as follows. 
The valve or valves of the tap keys being closed, there is evidently no 
pressure within the expansion chamber CD upstream of the calibrated 
passage 70. By virtue of its inherent expansion force, the metal bellows 
84 (FIG. 4) acts on the valve 72 via the valve lifter rod 83, the stroke 
of the metal bellows and hence that of the valve lifter rod being limited 
by impingement of the front surface 86 of the bellows on the bottom 89 of 
the bore 85. 
Conversely, when the tap is open, the circuit is placed under load and the 
high-pressure section HP of the cartridge C receives gas, the valve 72 
being lifted off the seat 71 by the valve lifter 83, with the result that 
the gas is allowed to enter the expansion chamber CD through the passage 
70 formed in the valve seat. The gas exerts a pressure throughout the 
front surface of the metal bellows whilst compressing it, and the valve 
lifter rod 83 is consequently moved rearwards. The valve 72 then assumes 
its closed position on the seat 71 so that the penetration of the fluid 
which is to be expanded into the expansion chamber CD is stopped. When the 
pressure drops in the expansion chamber, the force of the spring bellows 
84 pushes the valve 72 back to a balanced position. 
The delivery rate of the gas is determined by: the pressure prevailing in 
the expansion chamber CD, the cross-section of the calibrated orifice 81 
and the pressure of the consumer circuit. The pressure in the expansion 
chamber is determined by the metal bellows 82, adjustable in respect of 
compression by means of the adjusting screw 87. 
The operation of the cartridge C shown in FIGS. 6 and 7 will not be 
described in detail since it is analogous to that which has been 
described. 
While certain preferred embodiments of the invention have been illustrated 
by way of example in the drawings and particularly described, it will be 
understood that the invention is in no way limited to the embodiments 
shown and that various modifications may be made without departing from 
the scope of the following claims.