AU5945000A

AU5945000A - Regulator safety system

Info

Publication number: AU5945000A
Application number: AU59450/00A
Authority: AU
Inventors: Kenneth W Griggs
Original assignee: Cigweld Pty Ltd
Current assignee: Cigweld Pty Ltd
Priority date: 1999-09-15
Filing date: 2000-09-15
Publication date: 2001-03-29
Anticipated expiration: 2020-09-15
Also published as: AU750779B2

Description

P/00/01i1 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE

SPECIFICATION

STANDARD

PATENT

Invent ion Title: Regulator safety system The following statement is a full description of this invention, including the best method of performing it known to us: Freehills Carter Smith BeadteMELC6O370651.9 CD/::ODMA\WORLDOX\F:\WPFILES\TDCG\1 8421\BCW4626.OOC 1A REGULATOR SAFETY SYSTEM Field of the Invention The present invention relates to gas regulators and in particular to an improved safety system for gas regulators. The invention has particular application to piston or barrel regulators.

Background of the Invention Regulators are used in conjunction with a wide variety of gas equipment to control the pressure and/or flow of gas from a gas cylinder into the gas equipment, usually via a hose.

Gas regulators may include an inbuilt safety system as part of the regulator inlet. The safety system functions to prevent the occurrence, and safely limit the consequences of oxygen ignition and fires in the high pressure gas passages of oxygen and oxidising gas pressure regulators.

The majority of these ignitions/fires occur immediately after opening the gas cylinder valve when the operator is located immediately next to the regulator. The sudden increase in gas flow creates a pressure build up in the inlet of the regulator, rapidly increasing the temperature of the oxygen in the regulator as the cylinder valve is opened. The increase in temperature can in some cases be enough to ignite the gas. However, the risk of ignition is increased when the gas flow is contaminated. Particles in the gas flow can ignite relatively quickly once the temperature increases, and can also create sparks by impacting on each other. These ignitions and fires can result in the regulator rupturing (ie. throwing parts), or the regulator being partly or wholly consumed by the fire.

The inlet systems of current regulator designs typically include either a sintered filter or a mesh filter, upstream of a direct gas flow path to the soft seat of the regulator to substantially prevent entry of unwanted contamination. Mesh filters are easily pierced (ruptured) by the gas as the cylinder valve is opened.

Once this occurs, the filter is unable to function as intended. If the filter is fitted permanently, it can restrict the gas flow over time as filtered particles build up in it, CDI::ODMA\WORLDOX\F:\WPFILES\TDCG\1 8421 BCW4626.DOC 2 reducing the life of the regulator. If the filter is replaceable, then it is possible to operate the regulator without the filter in place leaving the regulator with no protection against contamination at all.

It is therefore an object of the present invention to provide an improved safety system for gas regulators wherein the occurrence of oxygen ignition and fire is minimised.

Summary of the Invention In a first aspect, the invention provides a gas regulator having an inlet system, the inlet system having an upstream end and a downstream end, the regulator including, in fluid communication: first filter means located at the upstream end of said inlet system; and second filter means permanently located at the downstream end of said inlet system.

In a second aspect, the invention provides a gas regulator having an inlet oeoo 15 system, the inlet system having an upstream end and a downstream end, the regulator including, in fluid communication: first filter means located at the upstream end of said inlet system; second filter means permanently located at the downstream end of said inlet system; and diffuser means located downstream of said first filter means and upstream of said second filter means.

In a third aspect, the invention provides a gas regulator having an inlet system, the inlet system having an upstream end and a downstream end, the regulator including, in fluid communication: first filter means located at the upstream end of said inlet system; CD/::ODMAXWORLDOXF:\WPF ILES\TDCG\1 8421\BCW4626.DOC 3 diffuser means located at the downstream end of said inlet system; and second filter means permanently located downstream of said first filter means and upstream of said diffuser means.

Preferably, in any aspect of the invention, the first filter means is removably located at the upstream end of the inlet system. Alternatively, the first filter means may be permanently located.

Preferably, the first and second filter means are sintered filters substantially consisting of multiplicity of small particles of the order of 30 microns. The exterior of the particles is locally melted so as to hold the particles together while leaving fine openings for gas passage.

Advantageously, the diffuser includes a labyrinth of small passageways, eg capillaries formed by turning and drilling. The passageways formed in the diffuser provide a convoluted flow path for the gas and together with the filters, provides a large gas "wetted" surface area for the gas for increased heat transfer. Preferably, 15 the diffuser also introduces at least one bend, of about 900 to force the gas to make a significant directional change.

Preferably, the regulator further includes a sealing washer at the upstream end of the inlet system providing a seal between the regulator and a gas cylinder valve. Advantageously, a securing screw is provided to hold the sealing washer and first filter means in position. The securing screw may be permanently or replaceably located in the inlet system.

Advantageously, the filters, diffuser, securing screw, and washer, are formed from materials having a high autogenous ignition temperature and high impact ignition resistance, such as brass, bronze, copper, and nickel.

Advantageously, the regulator further includes a soft seat located at the downstream end of inlet system. Preferably, the soft seat is formed fromrn a material having a low autogenous ignition temperature.

CD/::ODMA\WORLDOX\F:\WPFILES\TDCG\1 8421\BCW4626.DOC 4 Other objects and features will be in part apparent and in part pointed out hereinafter.

Brief Description of Drawings The invention will now be described by way of example, with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional view of a gas regulator including a safety system in accordance with an embodiment of the invention; Figure 2 is an enlargement of the safety system shown in Figure 1; Figure 3 is an enlargement of a portion of the safety system shown in Figures 1 and 2; Figure 4 is a cross sectional view on lines 4--4 of Figure 3; and Figure 5 is an axially-sectioned isometric view of a portion of the gas regulator of Figure 1.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

o Description of Preferred Embodiments Referring to Figures 1 and 2, a gas regulator 10 incorporating the safety o system of the invention is illustrated. The direction of the gas flow is shown by arrows A.

20 Regulator 10 includes main regulator body 12 of suitable material such as brass, having an axial inlet passage 14 which forms the regulator inlet. Located at the downstream end of the inlet passage 14 is a valve system generally designated 15 comprising a valve orifice 48 and a soft valve seat 16 (Fig. This valve seat 16 is preferably of a relatively soft material, such as nylon, Teflon CD/::ODMA\WORLDOX\F:AWPFILES\TDCG18421\BCW4626.DOC material, or Kel-F material. The valve system 15 is of conventional design and will not be described in further detail.

At the upstream end of the regulator inlet passage 14 is located a sealing washer 18. Sealing washer 18 serves to provide a leak tight seal between the gas cylinder valve and the main regulator body 12. Part of the external surface of a securing screw 20 may be slightly tapered so as to retain washer 18. The screw has an internal axial hexagonal gas passage 21 to enable easy assembly and removal when replacing a user replaceable inlet sintered filter 22 positioned in the inlet passage 14. As discussed below, the securing screw 20 may be permanently fixed. The securing screw 20 may be of brass, for example.

The securing screw 20 also holds the user replaceable inlet sintered filter 22 in place. User replaceable inlet sintered filter 22 acts as the first barrier in the safety system of the invention. Filter 22 is made up of a multiplicity of small particles sintered bronze or sintered cupro nickel) on the order of 30 microns.

The filter is manufactured by placing the particles in a mould and applying heat until localised regions of the outside surfaces of the particles melt and bond together, leaving fine openings between the bonds to allow passage of gas through the filter. Any foreign particles or contaminants in the inlet gas flow should **be trapped by the replaceable filter 22. When the amount of particles and contaminants trapped by the filter 22 increases to a level where the flow of gas is restricted, it can be replaced by the user. If the gases are ignited filter 22 assists in quenching the fire due to the large surface area of the particles that make up the filter 22 and the narrow passages through the filter. Sintered filters suitable for use in this invention are commercially available from Sintec Australia, Pty Ltd.

In one embodiment, the user replaceable inlet sintered filter 22 may instead be permanently fitted. In this case, securing screw 20 is permanently fixed at the upstream end of the regulator inlet.

A permanently fitted diffuser 24 is positioned in the inlet passage 14 downstream of the replaceable filter 22. The diffuser 24 has a labyrinth of small passageways that force the gas flow to break into many small flow paths thus preventing one large jet of gas from flowing directly downstream to the soft seat CD/::ODMANWORLDOX\F:AWPFILES\TDCG\1 8421\BCW4626.DOC 6 16. More particularly, the diffuser 24 may be formed by turning and drilling a solid cylindric body or block of a material such as brass, to have a plurality of generally longitudinal bores 36 eight 0.8mm-diameter bores spaced at equal intervals around the body), a circumferential groove 34 communicating with the downstream ends of the bores 36, and a plurality of generally radial bores 38 four 1.0mm-diameter bores) providing communication between the groove 34 and an outlet bore 40 a 2.0mm-diameter bore) extending to the downstream end of the diffuser body. The bores 36, 38 and 40 combine to form non-linear flow paths which force the gas moving through the diffuser to make significant directional changes in flow, especially at the junctures or bends 30, 32 between the longitudinal, radial and outlet bores. By breaking the flow of gas into many small paths and introducing changes in the flow direction, the momentum/kinetic energy of the gas is reduced. This in turn helps reduce the temperature rise in the regulator due to adiabatic compression. The many small flow paths also present a large surface area to the gas which allows thermal transfer, further reducing the temperature rise due to adiabatic compression. It will be understood that the number and size of the bores in the diffuser can vary e without departing from the scope of this invention. Also, the bores 36, 38 and may have shapes and configurations different from those shown in the drawings.

Generally speaking, the diameters of the bores 36, 38 and 40 should be made as :small as possible. Preferably, the length of each bore should be at least twice its diameter, and the angles between the bores 36, 38 and 40 are ninety degrees, although this angle can vary. Further, the total gas flow area of the bores should be such that the diffuser does not significantly restrict the flow of the gas through the inlet passage of the regulator. In general, the total flow area through the diffuser should be at least twice that of the flow area through the orifice 48. (The size of orifice 48 will vary, depending on the regulator. Two exemplary orifice :diameters are 0.5mm and about 0.9mm.) The diffuser 24 is either screwed or pressed into the main regulator body 12. If the diffuser is screwed into the body, as shown in the drawings, the upstream end or head of the diffuser can be formed with a multi-sided recess 42 for receiving a tool to facilitate rotation of the diffuser.

CD/::ODMA\WORLDOX\F:WPFILES\TDCG\1 8421\BCW4626.DOC 7 The pressure of the gas in the inlet passage 14 can be monitored by means of a high pressure gauge 26 which is mounted in an opening 44 (Fig. 3) in the regulator body 12 which communicates with the circumferential groove 34 in the diffuser 24.

A permanently fitted sintered inlet filter 28 is positioned in the inlet passage 14 immediately downstream of the diffuser 24. The permanently fitted filter 28 is formed in the same manner and has the same function as the user replaceable filter 22 except that it is not intended to be replaced. If the user tries to use the regulator with the user replaceable filter 22 removed, the permanently fitted sintered inlet filter 28 acts as a backup. As shown in the drawings Fig. 3), the permanent filter 28 is held captive between the downstream end of the diffuser 24 and an internal shoulder 46 in the inlet passage 14, but it will be understood that the filter 28 can be mounted in the passage 14 in other ways.

The regulator safety system of the present invention employs materials in construction that have a high autogenous ignition temperature and high impact ignition resistance, such as brass, bronze, copper, and nickel, for example.

It will be appreciated that the design of the regulator safety system of the eelS present invention offers many safety features. The inclusion of sintered filters 22, 28, having a large number of very small particles, to act as flame traps hinder the flow of any flame by providing a large gas "wetted" surface area as surface of the particles and a convolute gas flow path through the particles. The inclusion of diffuser 24 creates a convoluted gas flow path that intercepts a jet of high pressure gas direct from the cylinder valve, preventing it from impacting on the soft valve seat 16. The large particle surface areas presented to the gas flow by 25 the sintered filters 22, 28 additionally assist in lowering the temperature rise due to adiabatic compression of the gas as it enters the regulator immediately after the cylinder valve is opened.

It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

It will be understood that the term "comprises" or its grammatical variants as used herein is equivalent to the term "includes" and is not to be taken as excluding the presence of other elements or features.

.e

Claims

1. A gas regulator comprising: a regulator body; an inlet passage in the body having an upstream end and a downstream end; first filter means in the upstream end of said inlet passage; and second filter means in said inlet passage downstream from said first filter means.

2. A gas regulator as set forth in claim 1 wherein said second filter means is permanently mounted at the downstream end of the inlet passage. 10

3. A gas regulator as set forth in claim 2 wherein said first filter means is removable from the regulator.

4. A gas regulator as set forth in claim 2 wherein each of said first and second filter means comprises a sintered filter.

A gas regulator as set forth in claim 2 further comprising diffuser means in said inlet passage downstream from said first filter means, said diffuser means defining at least one non-linear flow path therethrough.

6. A gas regulator as set forth in claim 5 wherein said diffuser means is located upstream of said second filter means.

7. A gas regulator as set forth in claim 5 wherein said diffuser means comprises a diffuser body having a longitudinal axis and a plurality of generally longitudinal and generally radial bores therein forming a series of non-linear flow paths through the diffuser body. CD/::ODMA\WORLDOX\F:\WPFILES\TDCG\18421\BCW4626.DOC 9

8. A gas regulator as set forth in claim 7 further comprising a soft valve seat in said inlet passage downstream from said diffuser.

9. A gas regulator as set forth in claim 7 further comprising a pressure gage mounted on the regulator body in pressure communication with at least one bore in the diffuser body. COMWELD GROUP PTY LTD by Freehills Carter Smith Beadle Registered Patent Attorneys for the Applicant September 2000 :i.