AU2987901A

AU2987901A - Leakproof gas pressure regulator

Info

Publication number: AU2987901A
Application number: AU29879/01A
Authority: AU
Inventors: Peter Jeremy Foden
Original assignee: FLOATPAC Pty Ltd
Current assignee: FLOATPAC Pty Ltd
Priority date: 2000-02-09
Filing date: 2001-02-02
Publication date: 2001-08-20
Anticipated expiration: 2021-02-02
Also published as: CN1398331A; WO2001059342A1; AUPQ552700A0; HK1052545A1; NZ520336A; HK1052545B; CN1199017C; AU757045B2

Description

WO 01/59342 PCT/AU01/00092 LEAKPROOF GAS PRESSURE REGULATOR The present invention relates to a gas pressure regulator. In particular, the present invention relates to 5 a gas pressure regulator that is suitable for use in environments where leakage of gas through the gas regulator to the surrounding atmosphere is not permissible. Gas pressure regulators are used to control the 10 pressure or flow of gas supplied from a gas supply such as a gas cylinder to a receptacle. In certain circumstances, it is important that gas flowing from the gas supply cylinder to the receptacle not be released into the surrounding atmosphere. One important example is in the 15 supply of a fuel gas or an oxidising gas into a receptacle where there is a potential fire hazard in the surroundings. During the transport of live aquatic life by aircraft, it is necessary to supply oxygen to the vessel 20 containing the aquatic life. Conventional regulators used to supply oxygen to vessels containing aquatic life include vent openings so that, should the gas pressure regulator fail, pressure in the regulator will not build up to a point at which the regulator explodes or reaches such high 25 temperatures as to be a fire hazard. The vent openings also function to balance diaphragms against changes in ambient pressure. There are concerns surrounding the use of such 30 gas regulators in aircraft transportation due to the possible leakage of gases that may increase the fire hazard. In addition, in other applications where toxic gases are controlled in these-gas pressure regulators, there are also concerns for public health and safety. 35 It is an object of the present invention to provide a gas pressure regulator that does not have any gas WO 01/59342 PCT/AU01/00092 -2 leakage to the external atmosphere, and in which no single component can fail in a manner which will allow the supplied gas to escape to the surrounding atmosphere. 5 According to the present invention there is provided a gas pressure regulator for regulating the flow of gas from a gas supply to a receptacle, including: a regulator body including a gas inlet, a gas 10 outlet and a gas passageway extending between said inlet and said outlet, a first casing part coupled to the regulator body, and a first diaphragm interposed between said 15 regulator body and said first casing part capable of restricting the flow of gas through one point along said gas passageway, a second casing part coupled to the regulator 20 body, and a second diaphragm interposed between said regulator body and said first casing part capable of restricting the flow of gas through a second point along said gas passageway, 25 wherein the gas pressure regulator does not include any venting to the external atmosphere; wherein the regulator body and each casing part is of sufficient strength to withstand the full pressure of gas supply, so that should one diaphragm fail, the regulator can continue to function 30 without releasing gas to the atmosphere; and wherein the gas passageway includes a restricted region which restricts flow through the regulator should the second diaphragm fail. 35 As will be explained in further detail below, in the event of failure of one diaphragm, the gas pressure regulator will continue to restrict the flow of gas through WO 01/59342 PCT/AU01/00092 -3 the regulator to the receptacle to a certain extent, but not necessarily to the full extent initially set. Accordingly, the term "function" as used above should not be read so restrictively as to refer only to normal 5 operational functioning. Preferably, the first diaphragm is upstream of the second diaphragm. Accordingly, the first diaphragm forms part of a first stage of the regulator, and the 10 second diaphragm forms part of a second stage of the regulator. Preferably, the restricted region is located between the second diaphragm and the gas outlet. 15 Preferably, the first diaphragm can be controlled to reduce the output pressure to a suitably low value such that, should the second diaphragm fail, gas flow through the regulator can be limited to a safe level by the first 20 diaphragm and the restricted region. More preferably, the first diaphragm is pre-set to an appropriate position to reduce the output pressure at the first diaphragm to a suitably low value such that, should the second diaphragm fail, gas flow through the regulator can be limited to a 25 safe level by the first diaphragm and the restricted region. Preferably, the gas pressure regulator includes seals between adjacent elements of the device that prevent 30 gas escaping to the external atmosphere, and the seals are each sufficiently strong to withstand the full supply pressure of the supply gas. Preferably, the first and second casing parts 35 comprise first and second bonnets. Preferably, the first and second bonnets extend WO 01/59342 PCT/AU01/00092 -4 axially of the regulator body. More preferably, the first and second bonnets extend from opposite axial ends of the regulator body. According to one particularly preferred embodiment, the bonnets are axially aligned. 5 Preferably, the first bonnet includes a first control means, and the second bonnet includes a second control means for controlling flow of gas through respective first and second points along the gas flow path. 10 Preferably, the first control means is adapted to be pre set to reduce pressure to a preset level, and the second control means is adapted to be adjustable throughout operation of the regulator. For one example, the first control means may be in the form of a pre-setable adjusting 15 screw, and the second control means can be in the form of a control knob adjusting screw. According to this particularly preferred embodiment, the device includes seals between the bonnets and the adjusting screws of sufficient strength to contain the full pressure of the gas 20 supply. Preferably, the maximum flow rate of gas through the gas pressure regulator is less than or equal to 5 litres per minute. 25 Preferably, the first control means is in the form of a pre-setable adjusting screw. Preferably, the second control means is in the 30 form of a control knob adjusting screw. More preferably, the device includes seals between the bonnets and the adjusting screws of sufficient strength to contain the full pressure of the gas supply. 35 The present invention also provides for the use of a gas pressure regulator as described above in an WO 01/59342 PCT/AU01/00092 -5 arrangement for the transportation of aquatic life. Preferably the aquatic life is transported in an aircraft. The present invention will now be described in 5 further detail with reference to the drawings of a preferred embodiment of the invention in which: Figure 1 is a cross sectional view of the gas pressure regulator according to the preferred embodiment of 10 the invention, and Figure 2 is a perspective view of an arrangement for transporting fish including the gas pressure regulator illustrated in Figure 1. 15 The gas pressure regulator 1 according to the preferred embodiment of the invention has two stages for regulating the pressure of gas flowing from a gas supply to a receptacle to which gas is required to be supplied. The first stage is upstream of the second stage. As used in 20 the following description, "first" refers to an element in the first stage, and "second" refers to an element in the second stage. The gas pressure regulator 1 includes a regulator 25 body 2, and first and second casing parts in the form of first and second stage bonnets 3, 4 respectively. These parts 2, 3, 4 are formed from brass, but could be made from other materials such as bronze, stainless steel or titanium. Aluminium components are not appropriate in this 30 exemplified application due to the high fire hazard of aluminium components when used with a high pressure oxygen supply. The first and second stage bonnets 3, 4 are 35 coupled to the regulator body 2 by any appropriate means. According to the preferred embodiment illustrated, the first and second stage bonnets 3, 4 include internally WO 01/59342 PCT/AU01/00092 -6 screw-threaded ends adapted for mounting on to corresponding threaded regions of the regulator body 2. The regulator body 2 also includes a gas inlet 5, 5 a gas outlet 6, and a gas passageway 7 extending between the inlet and outlet 5, 6. The gas passageway runs via a first stage diaphragm valve assembly 25 and a second stage diaphragm valve assembly 25. As used in the specification, it will be understood to persons skilled in the art that 10 the term "diaphragm" is colloquially used to refer to a diaphragm valve or diaphragm valve assembly, as well as the actual diaphragm component of the valve. Accordingly, the term "diaphragm" should be interpreted to embrace those terms. 15 A gas supply, for example a gas cylinder, is connected to the gas inlet 5 via an inlet connector 8. The gas outlet is connected to a receptacle to which gas is required to be supplied. The gas pressure regulator of the 20 present invention is particularly suitable for the supply of an oxygen-containing gas to a live aquatic life tank, which is to be transported by aircraft from one location to another. In this particular environment, it is not permissible, and indeed it can be very dangerous, for the 25 oxygen-containing gas to escape or leak from the gas pressure regulator, or any other point between gas supply container and the receptacle. Interposed between the regulator body 2 and the 30 first stage bonnet 3 is a first diaphragm 9 of the first diaphragm valve assembly which is capable of restricting the flow of gas through a first stage of the gas pressure regulator, at a first location along the gas passageway. The first diaphragm controls opening and closing the valve 35 (not illustrated in detail) of the first diaphragm valve assembly to control flow of gas through the first stage. This is done in the manner of a conventional diaphragm WO 01/59342 PCT/AU01/00092 -7 valve. When there is a heavy demand on gas supply and the gas pressure on the face of the diaphragm falls significantly, the diaphragm spring pushes the valve wide open. When the demand for flow is reduced, the flow 5 through the wide open valve causes the pressure on the face of the diaphragm to rise rapidly. The diaphragm is pushed away from the valve assembly, against the force of the regulator spring, and the valve closes down by the action of a light internal spring (not illustrated). 10 The first stage diaphragm is sealingly coupled to the regulator body. The seal of the first diaphragm 9 to the regulator body also provides a seal between the regulator body 2 and the first stage bonnet 3. The first 15 stage bonnet 3 also includes a pre-setable adjusting screw 10. A seal is also provided between the pre-setable adjusting screw 10 and the first stage bonnet 3, in the form of a static seal 11. 20 The first stage bonnet does not include any venting to the external atmosphere. In contrast, all gas pressure regulators of the prior art commonly include venting in order to avoid potentially dangerous pressure build up in the regulator and to remove any back pressure 25 on the diaphragm. The first stage bonnet 3 is also of sufficient strength to withstand the full pressure of the gas supply, so that should the first diaphragm 9 fail, gas will not escape from the first stage of the gas pressure regulator 1. In addition, the various seals between 30 adjacent elements of the device that prevent gas escaping to the external atmosphere (ie. the seals between the regulator body 2 and the first stage bonnet 3, and between the first stage bonnet 3 and the pre-setable adjusting screw 10) are each of sufficient strength to withstand the 35 full supply pressure of the supply gas. These features also contribute to the leakproof nature of the gas pressure regulator.

WO 01/59342 PCT/AU01/00092 -8 The pre-setable adjusting screw 10 is twisted to pre-load a first spring 17 to an appropriate value to reduce the output pressure of the first stage of the 5 regulator to an appropriate level. Usually, the pre setting of the pre-setable adjusting screw is done by the manufacturer as a static setting during manufacture, or prior to sale of the gas pressure regulator. 10 The gas pressure regulator also includes a second stage diaphragm 12 of the second diaphragm valve assembly interposed between the regulator body 2 and the second stage bonnet 4, capable of restricting the flow of gas through a second stage of the gas pressure regulator at a 15 second location or point along the gas passageway. The second stage diaphragm 12 controls opening and closing of the valve 27 of the second valve diaphragm assembly to control flow of gas through the second stage in a similar manner to the first stage diaphragm. 20 The gas passageway 7 through the regulator body 2 includes an inter-stage passage section 13. The inter stage passage does not include any venting, by means of a vent valve or any other feature, to the external 25 atmosphere. The regulator body is also of sufficient strength to control the full supply pressure should the first diaphragm or the first stage of the gas pressure regulator fail. 30 Similarly to the first diaphragm 9, the second diaphragm 12 is sealingly coupled to the regulator body, and this seal also provides a seal between the regulator body 2 and the second stage bonnet 4. Adjustment of the second diaphragm 12 in the second stage of the gas pressure 35 regulator 1 is controlled by a control knob adjusting screw 14. Twisting of the control knob changes the equilibrium location of the second diaphragm 12, and therefore the WO 01/59342 PCT/AU01/00092 -9 output pressure of the second stage of the gas pressure regulator is modified. The control knob is of a type designed to be appropriate for operation during flow of gas through the gas pressure regulator 1. 5 A seal in the form of a sliding seal 15 is provided between the control knob adjusting screw and the second stage bonnet. This seal is of sufficient strength to retain the full gas supply should the second diaphragm 10 12 fail. The second stage bonnet 4 is also of sufficient strength to withstand the full supply pressure should the second diaphragm 12 fail. In the region of the gas passageway 7 between the 15 second diaphragm 12 and the gas outlet 6, there is provided a restricted region in the form of a fixed orifice 16. The fixed orifice 16 is of a size that would restrict the flow of gas through the regulator should the second stage diaphragm 12 fail. 20 In essence, the fixed orifice 16 sets a maximum flow of gas through the gas pressure regulator 1 in the event of failure of the second diaphragm 12. The actual maximum flow through the fixed orifice however will depend 25 on the setting of the first stage diaphragm, since the actual flow level is dependent on the gas pressure. Accordingly, reference to a maximum flow through the diaphragm should not be read narrowly so as to refer to a specific invariable maximum level. 30 The combination of features of the gas pressure regulator outlined above guard against any single component failure of the gas pressure regulator causing external leakage of the supplied gas. 35 In the event that the first diaphragm 9 fails, gas will not be able to leak through any region of the WO 01/59342 PCT/AU01/00092 - 10 first stage of the gas pressure regulator to the external atmosphere. In addition, the second stage is of sufficient strength to provide normal control of the full supply pressure passing to the second stage of the regulator. 5 Accordingly, the gas pressure regulator can continue to function without releasing gas to the atmosphere. It is to be understood, however, that the gas flow at the outlet port would be slightly lower than initially set with both the first and second diaphragms working. However, the gas 10 pressure regulator does continue to function in the sense that it continues to control the flow of gas from the gas supply to the receptacle. In order to be prepared to compensate for failure 15 of the second stage diaphragm, the preset outlet pressure from the first stage is set to a lower than usual value. By controlling the preset adjusting screw to this level, in the event of failure of the second stage diaphragm, the flow through the regulator is limited to an acceptable 20 value by the fixed orifice 16 near the outlet port. In this instance, there will be no external leakage of the control gas to the external atmosphere, and the gas pressure regulator will continue to function in the sense that it prevents the full gas supply to be able to flow 25 unhindered through the gas pressure regulator. Whilst the gas flow through the system will exceed the desired value, it will be restricted to an acceptable level, which is determined principally by the setting of the first stage diaphragm and the fixed orifice at the outlet port. 30 The various scenarios outlined above are summarised in the following table.

WO 01/59342 PCT/AU01/00092 - 11 Situation Leakage? Flow Both stages OK No Normal operation First stage failure No Almost normal operation, but backup in event of failure of a stage no longer present Second stage failure No Flow constant, at acceptable value Both stages fail No Flow higher than required (no longer in range of normal operational flow), but not unrestricted. According to the preferred embodiment of the invention, the gas pressure regulator is used in an 5 arrangement 19 for the transportation of aquatic life from one location to another by air. The regulator can be incorporated into a wide variety of arrangements. The arrangement of one embodiment includes a gas cylinder 20 for supplying oxygen, the gas pressure regulator 1 10 illustrated in Figure 1, and a vessel 21 with a sealed lid containing water and the aquatic life, such as fish. A low pressure oxygen supply line 22 leads from the gas pressure regulator 1. The vessel is also provided 15 with a non-spill gas vent 22. These elements are all housed within a protective cover 23 on top of the lid of the vessel 21. Many modifications may be made to the preferred 20 embodiment illustrated without departing from the spirit and scope of the invention. For example, whilst the gas pressure regulator includes two stages, the gas pressure WO 01/59342 PCT/AUO1/00092 - 12 regulator may be modified to incorporate a third stage, so as to provide a further back-up feature should any of the diaphragms of the gas pressure regulator fail. 5

Claims

1. A gas pressure regulator for regulating the flow of gas from a gas supply to a receptacle, including: 5 a regulator body including a gas inlet, a gas outlet and a gas passageway extending between said inlet and said outlet, 10 - a first casing part coupled to the regulator body, and a first diaphragm interposed between said regulator body and said first casing part capable of restricting the flow of gas through one point along said gas passageway, 15 a second casing part coupled to the regulator body, and a second diaphragm interposed between said regulator body and said first casing part capable of restricting the flow of gas through a second point along 20 said gas passageway, wherein the gas pressure regulator does not include any venting to the external atmosphere; wherein the regulator body and each casing part is of sufficient strength to 25 withstand the full pressure of gas supply, so that should one diaphragm fail, the regulator can continue to function without releasing gas to the atmosphere; and wherein the gas passageway includes a restricted region which restricts flow through the regulator should the second diaphragm 30 fail.

2. The gas pressure regulator as claimed in claim 1 wherein the first diaphragm is upstream of the second diaphragm. 35

3. The gas pressure regulator as claimed in claim 2, wherein the restricted region is located between the second WO 01/59342 PCT/AU01/00092 - 14 diaphragm and the gas outlet.

4. The gas pressure regulator as claimed in claim 2 or claim 3 wherein the first diaphragm can be controlled to 5 reduce the output pressure to a suitably low value such that, should the second diaphragm fail, gas flow through the regulator can be limited to a safe level by the first diaphragm and the restricted region. 10

5. The gas pressure regulator as claimed in claim 4, wherein the first diaphragm is pre-set to an appropriate position to reduce the output pressure at the first diaphragm to a suitably low value such that, should the second diaphragm fail, gas flow through the regulator can 15 be limited to a safe level by the first diaphragm and the restricted region.

6. The gas pressure regulator as claimed in any one of claims 2 to 5, wherein the gas pressure regulator 20 includes seals between adjacent elements of the device that prevent gas escaping to the external atmosphere, and the seals are each sufficiently strong to withstand the full supply pressure of the supply gas. 25

7. The gas pressure regulator as claimed in any one of claims 2 to 6, wherein the first and second casing parts comprise first and second bonnets.

8. The gas pressure regulator as claimed in claim 7, 30 wherein the first and second bonnets extend axially of the regulator body.

9. The gas pressure regulator as claimed in claim 8, wherein the first and second bonnets extend from opposite 35 axial ends of the regulator body.

10. The gas pressure regulator as claimed in any one WO 01/59342 PCT/AU01/00092 - 15 of claims 7 to 9, wherein the first bonnet includes a first control means, and the second bonnet includes a second control means for controlling flow of gas through respective first and second points along the gas flow path. 5

11. The gas pressure regulator as claimed in claim 10, wherein the first control means is adapted to be pre set to reduce flow to a preset level, and the second control means is adapted to be adjustable throughout 10 operation of the regulator.

12. The gas pressure regulator as claimed in claim 10 or claim 11, wherein the first control means is in the form of a pre-setable adjusting screw. 15

13. The gas pressure regulator as claimed in claim 12, wherein the second control means is in the form of a control knob adjusting screw. 20

14. The gas pressure regulator as claimed in claim 13, wherein the device includes seals between the bonnets and the adjusting screws of sufficient strength to contain the full pressure of the gas supply. 25

15. The gas pressure regulator as claimed in any one of claims 1 to 14, wherein the maximum flow rate of gas through the gas pressure regulator is less than or equal to 5 litres per minute. 30

16. Use of the gas pressure regulator as claimed in any one of claims 1 to 15 in an arrangement for the transportation of aquatic life.

17. Use according to claim 16, wherein the aquatic 35 life is transported by aircraft.

18. Gas pressure regulator substantially as herein WO 01/59342 PCT/AU01/00092 - 16 described with reference to the accompanying drawings.

19. Use of a gas pressure regulator substantially as herein described with reference to the accompanying 5 drawings in an arrangement for the transportation of aquatic life by aircraft.