EP0047676A2 - Atemschutzgerät - Google Patents

Atemschutzgerät Download PDF

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Publication number
EP0047676A2
EP0047676A2 EP81304141A EP81304141A EP0047676A2 EP 0047676 A2 EP0047676 A2 EP 0047676A2 EP 81304141 A EP81304141 A EP 81304141A EP 81304141 A EP81304141 A EP 81304141A EP 0047676 A2 EP0047676 A2 EP 0047676A2
Authority
EP
European Patent Office
Prior art keywords
piston
shut
chamber
inlet
pressure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP81304141A
Other languages
English (en)
French (fr)
Other versions
EP0047676B1 (de
EP0047676A3 (en
Inventor
Leonard John Feathers
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Chubb Panorama Ltd
Original Assignee
Chubb Panorama Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Chubb Panorama Ltd filed Critical Chubb Panorama Ltd
Publication of EP0047676A2 publication Critical patent/EP0047676A2/de
Publication of EP0047676A3 publication Critical patent/EP0047676A3/en
Application granted granted Critical
Publication of EP0047676B1 publication Critical patent/EP0047676B1/de
Expired legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A62—LIFE-SAVING; FIRE-FIGHTING
    • A62B—DEVICES, APPARATUS OR METHODS FOR LIFE-SAVING
    • A62B7/00—Respiratory apparatus

Definitions

  • the present invention relates to self-contained breathing apparatus such as may be worn, eg by firemen, rescue workers and the like who are required to perform tasks in noxious or oxygen-depleted environments, or by divers.
  • Such apparatus comprises a cylinder of compressed air or oxygen supported by a harness worn by the user, and a facemask, mouthpiece or the like breathing interface means to which gas is supplied from the cylinder via a flowpath which includes so-called lung-controlled or demand valve responsive to the respiration of the user to admit gas to the mask or the like at the variable rate necessary to satisfy the breathing need.
  • the pressure of the supplied gas is reduced from the value at which it is stored in the cylinder to a regulated intermediate value by a first stage pressure reducer located in the flowpath upstream of a separate demand valve, while in others the appropriate pressure reduction and flow control is achieved by the demand valve alone.
  • shut-off valve associated with the cylinder for shutting off the gas supply while the apparatus is not in use.
  • a pressure gauge located remote from the cylinder at a position where it can readily be seen by the user, eg supported by the harness on the user's chest, to indicate the state of charge of the cylinder during.use.
  • a hose from the gauge is tapped in to the gas supply flowpath at a suitable position downstream from the shut-off valve but upstream of the pressure-reducing means.
  • Breathing apparatus wherein in addition to a main gas supply flowpath as described above there is provided an auxiliary or bypass flowpath leading to the mask or the like from the main flowpath at a position downstream of the main shut-off valve.
  • This bypass flowpath incorporates a second shut-off valve which is normally closed but which can be opened if it becomes necessary,through some failure of the main flowpath, for the user to breathe through the bypass, and further includes a length of capillary hose to reduce the pressure of the supplied gas as it flows to the mask or the like.
  • Such a system can be effective to enable the user to continue breathing and conserve his gas supply in the event of a blockage of the main flowpath at a position downstream of its junction with the bypass.
  • the invention resides in breathing apparatus comprising a source of pressurised breathing gas; breathing interface means; a first flowpath leading from said source to said interface means, such flowpath including shut-off means and downstream thereof pressure-reducing and flow-control means; and a second flowpath leading from said source to said interface means, said second flowpath including shut-off and pressure-reducing means and being arranged to deliver gas from said source to said interface means, when the second-mentioned shut-off means are opened, independently of the first-mentioned shut-off, pressure-reducing and flow-control means.
  • the second (bypass) flowpath provides a true parallel path to the first (main) flowpath, which latter can be isolated by closure of the first-mentioned shut-off means without affecting the ability of the second flowpath to deliver gas to the interface means.
  • the invention provides a combined shut-off and pressure-reducing valve comprising a piston slidably borne within a chamber; an inlet to and an outlet from the chamber respectively upstream and downstream of the piston; the upstream end of the piston being adapted to seat in relation to said inlet to shut off fluid flow therethrough; the piston having a passageway through it to conduct fluid through the chamber from its inlet to its outlet when the inlet is opened by unseating of the piston from the inlet; the downstream end of the piston being of greater effective cross-sectional area than its upstream end; and control means which are operable selectively to urge the piston into a position in which its upstream end seats in relation to the chamber inlet as aforesaid, or to release the piston for sliding movement within the chamber.
  • Such a valve is particularly, though not exclusively, useful to provide the shut-off and pressure-reducing means of the second flowpath of breathing apparatus according to the first-defined aspect of the invention, as will be more clearly understood from the ensuing particular description.
  • the invention resides in a valve assembly for use in association with a gas cylinder in breathing apparatus according to the first-defined aspect of the invention, and which comprises a body including a passageway to lead gas from the cylinder; a first shut-off valve mounted to said body; a second shut-off valve mounted to said body; and preferably a cylinder pressure gauge and/or cylinder pressure relief means (e.g. a burst disc) mounted to said body; with each of said first shut-off valve, said second shut-off valve, any said pressure gauge and any said pressure relief means communicating independently of one another with said passageway.
  • a cylinder pressure gauge and/or cylinder pressure relief means e.g. a burst disc
  • the body is of generally rectangular planform with said first shut-off valve mounted to a first side thereof, said second shut-off valve mounted to a second side thereof and any said pressure gauge and/or pressure relief means mounted to a third side thereof.
  • an outlet connection from said first shut-off valve is preferably located to the fourth side of the body, as may also be an outlet connection from said second shut-off valve.
  • the breathing apparatus includes a cylinder 1 of compressed air which in use is supported on the user's back in the conventional inverted attitude by means of a suitable harness assembly (not shown).
  • air for breathing is lead out of the cylinder 1 through a shut-off valve 2 to a first stage pressure reducer 3 which in accordance with known techniques provides air via a low pressure hose 4 to a demand valve 5 at a substantially constant, reduced pressure.
  • the demand valve 5, which functions to admit air to a facemask 6 at a variable rate in response to the respiratory efforts of the user, is preferably constructed in accordance with the invention disclosed in our published United Kingdom patent application no. 2054207 and coupled to a tubed inlet 7 of the facemask in accordance with the invention disclosed in our copending United Kingdom patent application 8111796 Exhaled air is vented from the facemask through a conventional exhalation valve 8.
  • This hose leads to a remote pressure gauge and low cylinder pressure warning whistle 10 of conventional form, located e.g. on the user's chest at a position where the reading of the gauge, indicative of the state of charge of the cylinder 1, can be easily seen.
  • a second shut-off valve 11 Connected to the cylinder 1 in parallel with the main shut-off valve 2 is a second shut-off valve 11 which also combines the function of a pressure reducer as will be more fully described hereinafter.
  • a second low pressure (bypass) hose 12 leads to the facemask 6,.to open into the inlet 7 of the mask through a connector 7A .at a position downstream of the working parts of the demand valve 5.
  • the valve 11 is maintained closed.
  • any of the components 2, 3, 4, 5 of the main air supply flowpath or of the gauge/whistle spur are the valve 11 which also combines the function of a pressure reducer as will be more fully described hereinafter.
  • valve 2 can be closed to isolate the main flowpath from the cylinder 1 and the valve 11 can be opened to maintain a supply of air from the cylinder to the mask via the hose 12. It will be noted that the flowpath provided by the components 11 and 12 leads directly from the cylinder 1 to the mask 6, bypassing all of the components of the main supply flowpath including the valve 2.
  • valve assembly 13 secured to the cylinder 1, together with.
  • two other components which form permanent parts of the cylinder assembly viz a second pressure gauge 14 and a burst disc unit 15, the latter to protect against over-pressure in the cylinder.
  • the construction of the valve assembly 13 will now be more fully described with reference to Figures 3, 4 and 5.
  • the assembly 13 comprises a body 16 of generally rectangular planform with two long slab sides 17, 18 and a threaded spigot 19 by which the assembly is screwed into the neck of the cylinder (not shown) to be sealed thereagainst with an O-ring 20.
  • Adjacent to the spigot 19 the body 16 has a neck provided with an external annular groove 21 whereby the cylinder assembly can be supported by a slotted mounting bracket in accordance with the invention disclosed in our published United Kingdom patent application no. 2064636
  • the spigot 19 carries a dip tube 22 ( Figure 4) through which air from the cylinder is lead to a central bore 23 in the body, the bore 23 intersecting with. four further bores 24-27.
  • the first intersecting or sub-bore 24 is aligned with the longitudinal direction of the body 16 (i.e. as represented by the axis A in Figure 3) and receives the screw-threaded spigot 28 of the cylinder pressure gauge 14 ( Figure 5) sealed to the bore by an O-ring 29.
  • the mechanism of the'gauge can be of conventional form, including an automatic self-sealing valve which closes in the event of any leakage of air out of the bore through the gauge.
  • the second sub-bore 25 intersects with the bore 23 at right-angles to the longitudinal direction of the body 16 and leads to a screw-threaded spigot 30 opening from the side 17 of the body ( Figures 3 and 4).
  • a chamber 31 which receives in screw-threaded relation a barrel 32 retaining the conical head 33 of the main shut-off valve 2.
  • the valve further comprises a handwheel 34 with a stem 35 journalled in an extension 36 of the chamber 31 and retained by a cap 37 screwed on to the spigot 30.
  • An O-ring 38 surrounding the stem 35 seals the chambers 31/36 against leakage.
  • the valve head 33 co-operates with a seat defined at the junction of the bore 25 with the chamber 31, and the head can be moved towards or away from the seat to close or open the valve by rotation of the handwheel 34 in the appropriate sense.
  • Rotation of the handwheel is transmitted from its stem 35 to the barrel 32 through a non-circular drive link 39 which permits the relative axial movement between the barrel and stem occasioned by the barrel's screw-threaded mounting.
  • Rotation of the barrel 32 to withdraw the head 33 from its seat and thereby open the valve 2 permits air to flow from the bore 25 to the chamber 31 and thence through a bore 40 which leads from the chamber to a threaded spigot 41 opening from the opposite side 18 of the body 16, the axis of the bore 40 and spigot 41 being parallel to, but offset from, the axis of the bore 25 and spigot 30.
  • the bore 40 leads air to the pressure reducer 3 of the main flowpath, shown in chain line in Figure 3.
  • This pressure reducer does not form part of the cylinder valve assembly 13 proper but is demountably attachable thereto by means of a knurled ring 42 held captive on the body of the reducer and screwed onto the spigot 41.
  • the reducer remains assembled with the demand valve, mask and harness of the breathing apparatus throughout each use of the apparatus, and when the cylinder assembly (i.e. the cylinder 1 together with the valve assembly 13) is replaced during use or between uses the reducer 3 is detached from the spigot 41 of the old cylinder assembly and reattached to the corresponding spigot of its replacement.
  • the high pressure and low pressure hoses 9 and 4 lead from the body of the reducer 3 respectively upstream and downstream of its working parts.
  • the spigot 41 is also used as the inlet to the cylinder assembly when being refilled.
  • the third sub-bore 26 ( Figure 5) is aligned with the longitudinal direction of the body 16, i.e. parallel with the pressure gauge bore 24, and leads from the central bore 23 towards the same short side 43 of the body as does the bore 24.
  • the bore 26 opens out into a larger diameter tapped bore 44 into which the burst disc unit 15 is screwed and sealed by an O-ring 45.
  • the unit 15 comprises a housing 46 in the form of a hollow nut having a tapped bore 47 opening to the bore 44 and within which. the burst disc itself (48) is clamped by means of a screw-threaded sleeve 49.
  • a passage 50 leads from the downstream end of the bore 47 to openings 51 in the head of the housing 46 so that in use the disc 48 is subjected to the difference between the cylinder pressure transmitted to bore 44, and ambient.
  • the disc 48 is adapted to rupture to vent the cylinder contents through the openings 51.
  • the fourth sub-bore 27 ( Figure 5) is also aligned with the longitudinal direction of the body 16 and opens from the central bore 23 opposite to the burst disc bore 26. It leads to a stepped-diameter chamber 52A/B/C within which is the piston 53 of the combined shut-off valve and pressure reducer 11 of the bypass flowpath.
  • the piston 53 is of stepped diameter matching the first two sections 52A, 52B of the chamber and is slidably sealed thereagainst by respective O-rings 54 and 55. Between the two O-rings the chamber is vented through an opening 56.
  • the valve further comprises a handwheel 57 with a stem 58 screwed into a tapped extension 59 of the chamber 52 and sealed against the chamber section 52C by an 0-ring 60.
  • the handwheel 57 is aligned at right-angles to the handwheel 34 of the main shut-off valve 2 and is of a different shape so that the user can readily distinguish between them by touch alone.
  • This bore constitutes the outlet from the valve assembly 13 for the bypass flowpath and plugged into it is a hollow spigot 67 connected to the bypass hose 12.
  • the spigot 67 is a simple push fit in the bore 66 and is sealed thereagainst by an 0-ring 68.
  • the spigot is held in place in the bore by virtue of the overlap of the knurled ring 42 of the main pressure reducer 3 with the flange 69 of the spigot, as indicated in Figures 3 and 5.
  • This provides a simple but secure means of connecting up the bypass hose 12 to the cylinder assembly, together with the reducer 3, whenever a cylinder assembly is changed.
  • valve 11 If the valve 11 is opened while the cylinder remains at its full pressure, conditions are established, it is speculated, such that the flow of air passing through the bore 27 and into the chamber section 52A attains a supersonic velocity, or in other words that the flow of air in the bore 27 becomes "choked"; under these choked conditions the rate of flow which the bore 27 is capable of passing is limited. These conditions prevail so long as the ratio of the cylinder pressure upstream of the bore 27 to the pressure in the chamber section 52A downstream of the bore 27 is above a certain critical value. However, as the cylinder becomes progressively depleted the upstream pressure will begin to fall until at a certain value the conditions for choked flow no longer exist and the flow velocity through bore 27 falls to a subsonic value.
  • the position of the piston at any time is determined by the balance of thrust on its upstream and downstream faces, or in other words on the difference between the pressure upstream of the 0-ring 54 integrated over the effective upstream surface area of the piston and the pressure downstream of the 0-ring 55 integrated over the effective downstream surface area of the piston.
  • the piston has a greater effective downstream surface area than upstream surface area.
  • the pressure downstream of O-ring 55 and the pressure upstream of O-ring 54 are related by virtue of the connection made between the upstream and downstream ends of the piston by its passageway 64, a certain pressure drop being encountered by the flow passing through this passageway.
  • the actual position adopted by the piston is of course that in which the orifice is restricted to the extent which results in the upstream and downstream thrusts on the piston cancelling out.
  • the piston moves gradually rightwards again under the balance of the upstream and downstream pressure forces, so that its head 63 opens up the associated orifice to compensate for the falling cylinder pressure.
  • the result of this action is to give an approximately constant bypass flow for the period following the transition from choked flow and to permit the air supply to be conserved for a period long enough for the user of the apparatus to make an escape following the change-over to "bypass" breathing, even if that change-over is made at a relatively late stage during a working cycle.
  • valve assembly described in relation to Figures 3 to 5 permits its various component parts to be dis - posed in juxtaposition in a highly compact manner, as will be appreciated from a consideration of those figures.
  • an assembly 13 as illustrated, together with the pressure reducer 3 can be mounted to a cylinder of, say, seven inches (178 mm) diameter with no part of the assembly protruding outside the bounds of the project area of the cylinder, as indicated at 1 in Figure 3.

Landscapes

  • Health & Medical Sciences (AREA)
  • Pulmonology (AREA)
  • General Health & Medical Sciences (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Respiratory Apparatuses And Protective Means (AREA)
EP19810304141 1980-09-10 1981-09-10 Atemschutzgerät Expired EP0047676B1 (de)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB8029301 1980-09-10
GB8029301 1980-09-10
GB8102795 1981-01-30
GB8102795 1981-01-30

Publications (3)

Publication Number Publication Date
EP0047676A2 true EP0047676A2 (de) 1982-03-17
EP0047676A3 EP0047676A3 (en) 1982-09-08
EP0047676B1 EP0047676B1 (de) 1984-11-07

Family

ID=26276849

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19810304141 Expired EP0047676B1 (de) 1980-09-10 1981-09-10 Atemschutzgerät

Country Status (4)

Country Link
EP (1) EP0047676B1 (de)
CA (1) CA1183058A (de)
DE (1) DE3167101D1 (de)
GB (1) GB2084882B (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2149306C1 (ru) * 1995-09-23 2000-05-20 Дзе Секретэри Оф Стейт Фор Дефенс Устройство для хранения газа
GB2427366A (en) * 2005-06-21 2006-12-27 Alex Deas Fault tolerant fail safe rebreather control device and method

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10201250C1 (de) * 2002-01-11 2003-05-28 Msa Auer Gmbh Druckluftversorgungssystem für ein Preßluftatemgerät

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB940581A (en) * 1960-05-30 1963-10-30 Sierra Eng Co A valve assembly for breathing apparatus
DE1126738B (de) * 1960-08-17 1962-03-29 Draegerwerk Ag Atemschutzgeraet mit lungengesteuertem Atemgaszufuehrungsventil, das an einen Druckminderer angeschlossen ist

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2149306C1 (ru) * 1995-09-23 2000-05-20 Дзе Секретэри Оф Стейт Фор Дефенс Устройство для хранения газа
GB2427366A (en) * 2005-06-21 2006-12-27 Alex Deas Fault tolerant fail safe rebreather control device and method

Also Published As

Publication number Publication date
GB2084882B (en) 1984-07-25
EP0047676B1 (de) 1984-11-07
EP0047676A3 (en) 1982-09-08
CA1183058A (en) 1985-02-26
GB2084882A (en) 1982-04-21
DE3167101D1 (en) 1984-12-13

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