CA2426638C - A working enclosure - Google Patents
A working enclosure Download PDFInfo
- Publication number
- CA2426638C CA2426638C CA002426638A CA2426638A CA2426638C CA 2426638 C CA2426638 C CA 2426638C CA 002426638 A CA002426638 A CA 002426638A CA 2426638 A CA2426638 A CA 2426638A CA 2426638 C CA2426638 C CA 2426638C
- Authority
- CA
- Canada
- Prior art keywords
- canopy
- enclosure
- working
- air
- enclosure according
- 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.)
- Expired - Fee Related
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B08—CLEANING
- B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
- B08B15/00—Preventing escape of dirt or fumes from the area where they are produced; Collecting or removing dirt or fumes from that area
- B08B15/02—Preventing escape of dirt or fumes from the area where they are produced; Collecting or removing dirt or fumes from that area using chambers or hoods covering the area
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F3/00—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems
- F24F3/12—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling
- F24F3/16—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling by purification, e.g. by filtering; by sterilisation; by ozonisation
- F24F3/163—Clean air work stations, i.e. selected areas within a space which filtered air is passed
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/0001—Control or safety arrangements for ventilation
- F24F2011/0002—Control or safety arrangements for ventilation for admittance of outside air
- F24F2011/0004—Control or safety arrangements for ventilation for admittance of outside air to create overpressure in a room
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Ventilation (AREA)
Abstract
A working enclosure adapted to provide a clean air zone within a potentially hazard environment such as an oil storage tank, the enclosure comprising a canopy (10) supported by a frame (11) and having a skirt (12) to be held in close proximity with the tank wall by magnetic pads (13). An operator may enter and leave the canopy via an air lock (33), and a supply of clean air from a fan (23) is supplied to the interior of the canopy by an inlet duct (20) and maintained at a slight over pressure therein by a controlled air outlet duct (30). In the clean air zone created by the enclosure an operator on suspension lines (18) may carry out "hot work" on the tank wall while the supply of clean air is monitored, and the operation shut down automatically in the event of air contamination.
Description
_ 1..
A WORKING ENCLOSTJRE
TI-11S INVF.NT1C)N concerns a working enclosure adapted to provide a clean air zoy.Ze within a potentially hazardous environment.
The inveni:ion is particularly though not exclusively concerned with the provision of a clean air zone in the form of a habitat within which sa-~~alted "hot work" may he carried out. t Iot work may be deemed to ~~e any activity which has the potential to introduce a source of ignition into a zone which may contain a gas and air mixture within a flammable range. The lower limit of such a range may be defined as the concentration below which there is insufficient flammable g;as to support combustion and the upper Limit may be the concentration above which there is insufficient air to support combustion. Such work is often carried out in vessels adapted to contain gas or flammable liquids such as the oil storage tanks of crude oiI carriers. It is sometimes necessary, to carry out, when such vessel;> are empty, repair work on parts of the internal structure. This work nay involve welding or c:utdng, and residues of gas and oil can cause an explosion when a source of ignition is intradueed into such a potentially hazardous environment.
Patent specification No. G8 23I 1847 describes a working enclosure adapted to provide a clean air zone within a potentially hazardous environment, the enclosure comprising a canopy adapted to cover at Ieast a part of a working surface to define therewith a clean air zane, at least one inlet duct connecting said zone to a supply afc~leun air, means to r~~onitor the content of the air supplied to said zone, and alarm/ shut down means responsive to the monit~~ring means.
The term "clean air" is to be construed as including either fresh clean air which is free of acutely inflammable gases, or for example., a mixture of clean air and an inert gas.
According to the present invention such a working enclosure is improved by the provision of means to discharge air from the enclosure to e;~tablish a controlled operating air pressure within the enclosure.
The discharge means may k~e a duct having a diameter less than that e>f t:he clean air inlet duct.
The operating air pressure within the enclosure may be controlled within the range of O.I to U.3 bar above ambient pressure outside the canopy.
An air lock may be provided in the canopy wall to enable operator access without substantially affecting the operating air pressure within the canopy.
Means rr~ay be provided to direct air circulation around the interior of the c.anapy thus to ensure substantially complete scavenging of any contaminant gases therefrom.
The canopy may be provided :in the form of a flexible shroud or a rigid enclo~,~ure or bubble.
Preferably,. the canopy also includes means whereby the edges of the canopy nay be maintained in close relationship with the working surface:.
An embouiwent of the i.nvtsntion will now be described, by way of example onl~.r, with reference to the accompanying drawings in which:-Fig. 1 is a perspective view of a working enclosure as described in specification GB 23I1847 and occupied bye an operator in readiness to carry out work on a u~ertical surface within, far example, an emptied c>il tank:
Fig. 2 i;~ a schernatie elevation of a working enclosure: ~~nac~e in accordance with the invention and locai:ed against a vertical wall;
and Fig. 3 is a schematic elevatiux~ of a rx~odified form of enclosure when located against a horizontal surface.
The cancyy IO made from, for example, a durable material such as nylon ~ pre-treated or lined with a fire prevention substance or blanket, is supported by a frame l I and has a _.
peripheral skirt 12 adapted to locate closely against a working surface to which the device may be applied and retained by magnetic pads 13. The canopy is supported from above by rigging rapes 14 and 1 G. A sealable access flap 16 is provided through which an operator 1? m:~y enter and leave the enclosure. One or more suspension lines 'l 8 to support the operator, pass into the canopy 10 through a generally sealed aperture 19 at the top of the canopy. Thus the enclosure is located temporarily in a fixed position against the working surface and in substantially sealed engagement therewith try .means of the skirt I2, the flap 16 and the aperture 1 ~.
An air° inlet duct 20 is connected to the canopy wall and communicates witr~ tl~e interior of the enclosure. The duct is preferably made from a flexible material and ,passes upwardly out of the hazardous environment, for example, through an aperture in a decking panel 21 and is supported above same by a frame 22 at the upper open end of which there is provided a fan 23 supplying air through t:he duct 20 into the enclosure. The fan 23 is associated with a sensing or monitoring device (not shown) which is further associated with a.n adjacent or remote alarm/ shut down system for a purpose to be described.
Within an enclosure as described the operator may carry out welding, cutting or similar operations without the risk of causing an explosion since clean air is ducted into the enclosure at a slight over-pressure thus bleeding from the flap I6 and aperture 19, and around the skirt I2.
The upstanding frame 22 ensures that the fan supplying clean air is disposed well above the deck 21 and any low-lying gases which rnay be present.
1'he sensing or monitoring device associated with the fan 23 is adapted to detect the presence of a toxic or inflammable contaminant in the air being supplied to the enclosure, and if present will either sound an alarm to alert the operator or other staff thus to discontinue the hat work, or to shut down the supply of power to whatever hot. work tools are being used in the enclosure, or simply to shut down the fan supplying the contaminated air tc~ the duct 20.
When the vsrorking surface upon which the hot work is being carried out is located between two potentially hazardous zones, for example, when repairing a bulkhead separating two hydro-carbon storage tanks, a second enclosure similar to that described may be positioned on the opposite side of the bulkhead whereat local heating of the working surface may otherwise create an explosive condition. .
Referring now to Figs. :~ and 3 which schematically illustrate an improverne:ot in accordance with. the present invention, Fig. 'Z depicting the working enclosure located against a vertical surface, and Fiy;. 3 depicting the enclosure against a horizontal surface, therre is provided a discharge duct 30 in communication with the: iruterior of the canopy at a position rermote from that at which the air inlet duct 20 is connected. The diameter of the discharl;e duct 30 is less than that of the inlet duct 20 thus to ensure a con trc:~lled over pressure within the canopy, of between O.I and 0.3 b:~r above ambient pressure outside of the canopy. If required, an adjustable constriction of pipe 30 may be provided whereby the rata c3f discharge of air there through may be selected.
A bafflN 3 I within the canopy directa air circulation axound the interior of the canopy as indicated by arrows ~2. This ensures stabsta:ntially conr~.plete scavenging of any contaminant gases therefrom.
Thus, by controlling the discharge of air from the canopy as opposed to th<~ expedient of allowing it to bleed through the aperture I9 as in Fig. I or around the skirt 12, maintains a controlled amount of air over pressure within the canopy thus avoiding discomfort for personnel within the enclosure or insufficient pressured to ensure correct operation thereof.
An air fork 3~ is attached to the wall of the canopy to enable operator access without substantially affecting the operating air pressure ~uithxn the canopy.
Referring; raovv to Fig. 3 there is shown an alternative configuration for the enclosure when located an a horizontal working surface. In this example, the air infra and discharge duds are connected to one end wall of the canopy while the access air lock is located on tae opposite end wall.
-S.)-It is not inaended to limit the invention to the above details. For example, the canopy 10 may be produced in the form of a rigid pre-shaped en<:;lasure, and the air lock 33 may be omitted in an application where the canopy is to be disposed over a horizontal surface and lowered into place with an operator already in position. Indeed, the form of the enclosure may differ in many respects depending upon the application and location of the work to be carried oat.
A WORKING ENCLOSTJRE
TI-11S INVF.NT1C)N concerns a working enclosure adapted to provide a clean air zoy.Ze within a potentially hazardous environment.
The inveni:ion is particularly though not exclusively concerned with the provision of a clean air zone in the form of a habitat within which sa-~~alted "hot work" may he carried out. t Iot work may be deemed to ~~e any activity which has the potential to introduce a source of ignition into a zone which may contain a gas and air mixture within a flammable range. The lower limit of such a range may be defined as the concentration below which there is insufficient flammable g;as to support combustion and the upper Limit may be the concentration above which there is insufficient air to support combustion. Such work is often carried out in vessels adapted to contain gas or flammable liquids such as the oil storage tanks of crude oiI carriers. It is sometimes necessary, to carry out, when such vessel;> are empty, repair work on parts of the internal structure. This work nay involve welding or c:utdng, and residues of gas and oil can cause an explosion when a source of ignition is intradueed into such a potentially hazardous environment.
Patent specification No. G8 23I 1847 describes a working enclosure adapted to provide a clean air zone within a potentially hazardous environment, the enclosure comprising a canopy adapted to cover at Ieast a part of a working surface to define therewith a clean air zane, at least one inlet duct connecting said zone to a supply afc~leun air, means to r~~onitor the content of the air supplied to said zone, and alarm/ shut down means responsive to the monit~~ring means.
The term "clean air" is to be construed as including either fresh clean air which is free of acutely inflammable gases, or for example., a mixture of clean air and an inert gas.
According to the present invention such a working enclosure is improved by the provision of means to discharge air from the enclosure to e;~tablish a controlled operating air pressure within the enclosure.
The discharge means may k~e a duct having a diameter less than that e>f t:he clean air inlet duct.
The operating air pressure within the enclosure may be controlled within the range of O.I to U.3 bar above ambient pressure outside the canopy.
An air lock may be provided in the canopy wall to enable operator access without substantially affecting the operating air pressure within the canopy.
Means rr~ay be provided to direct air circulation around the interior of the c.anapy thus to ensure substantially complete scavenging of any contaminant gases therefrom.
The canopy may be provided :in the form of a flexible shroud or a rigid enclo~,~ure or bubble.
Preferably,. the canopy also includes means whereby the edges of the canopy nay be maintained in close relationship with the working surface:.
An embouiwent of the i.nvtsntion will now be described, by way of example onl~.r, with reference to the accompanying drawings in which:-Fig. 1 is a perspective view of a working enclosure as described in specification GB 23I1847 and occupied bye an operator in readiness to carry out work on a u~ertical surface within, far example, an emptied c>il tank:
Fig. 2 i;~ a schernatie elevation of a working enclosure: ~~nac~e in accordance with the invention and locai:ed against a vertical wall;
and Fig. 3 is a schematic elevatiux~ of a rx~odified form of enclosure when located against a horizontal surface.
The cancyy IO made from, for example, a durable material such as nylon ~ pre-treated or lined with a fire prevention substance or blanket, is supported by a frame l I and has a _.
peripheral skirt 12 adapted to locate closely against a working surface to which the device may be applied and retained by magnetic pads 13. The canopy is supported from above by rigging rapes 14 and 1 G. A sealable access flap 16 is provided through which an operator 1? m:~y enter and leave the enclosure. One or more suspension lines 'l 8 to support the operator, pass into the canopy 10 through a generally sealed aperture 19 at the top of the canopy. Thus the enclosure is located temporarily in a fixed position against the working surface and in substantially sealed engagement therewith try .means of the skirt I2, the flap 16 and the aperture 1 ~.
An air° inlet duct 20 is connected to the canopy wall and communicates witr~ tl~e interior of the enclosure. The duct is preferably made from a flexible material and ,passes upwardly out of the hazardous environment, for example, through an aperture in a decking panel 21 and is supported above same by a frame 22 at the upper open end of which there is provided a fan 23 supplying air through t:he duct 20 into the enclosure. The fan 23 is associated with a sensing or monitoring device (not shown) which is further associated with a.n adjacent or remote alarm/ shut down system for a purpose to be described.
Within an enclosure as described the operator may carry out welding, cutting or similar operations without the risk of causing an explosion since clean air is ducted into the enclosure at a slight over-pressure thus bleeding from the flap I6 and aperture 19, and around the skirt I2.
The upstanding frame 22 ensures that the fan supplying clean air is disposed well above the deck 21 and any low-lying gases which rnay be present.
1'he sensing or monitoring device associated with the fan 23 is adapted to detect the presence of a toxic or inflammable contaminant in the air being supplied to the enclosure, and if present will either sound an alarm to alert the operator or other staff thus to discontinue the hat work, or to shut down the supply of power to whatever hot. work tools are being used in the enclosure, or simply to shut down the fan supplying the contaminated air tc~ the duct 20.
When the vsrorking surface upon which the hot work is being carried out is located between two potentially hazardous zones, for example, when repairing a bulkhead separating two hydro-carbon storage tanks, a second enclosure similar to that described may be positioned on the opposite side of the bulkhead whereat local heating of the working surface may otherwise create an explosive condition. .
Referring now to Figs. :~ and 3 which schematically illustrate an improverne:ot in accordance with. the present invention, Fig. 'Z depicting the working enclosure located against a vertical surface, and Fiy;. 3 depicting the enclosure against a horizontal surface, therre is provided a discharge duct 30 in communication with the: iruterior of the canopy at a position rermote from that at which the air inlet duct 20 is connected. The diameter of the discharl;e duct 30 is less than that of the inlet duct 20 thus to ensure a con trc:~lled over pressure within the canopy, of between O.I and 0.3 b:~r above ambient pressure outside of the canopy. If required, an adjustable constriction of pipe 30 may be provided whereby the rata c3f discharge of air there through may be selected.
A bafflN 3 I within the canopy directa air circulation axound the interior of the canopy as indicated by arrows ~2. This ensures stabsta:ntially conr~.plete scavenging of any contaminant gases therefrom.
Thus, by controlling the discharge of air from the canopy as opposed to th<~ expedient of allowing it to bleed through the aperture I9 as in Fig. I or around the skirt 12, maintains a controlled amount of air over pressure within the canopy thus avoiding discomfort for personnel within the enclosure or insufficient pressured to ensure correct operation thereof.
An air fork 3~ is attached to the wall of the canopy to enable operator access without substantially affecting the operating air pressure ~uithxn the canopy.
Referring; raovv to Fig. 3 there is shown an alternative configuration for the enclosure when located an a horizontal working surface. In this example, the air infra and discharge duds are connected to one end wall of the canopy while the access air lock is located on tae opposite end wall.
-S.)-It is not inaended to limit the invention to the above details. For example, the canopy 10 may be produced in the form of a rigid pre-shaped en<:;lasure, and the air lock 33 may be omitted in an application where the canopy is to be disposed over a horizontal surface and lowered into place with an operator already in position. Indeed, the form of the enclosure may differ in many respects depending upon the application and location of the work to be carried oat.
Claims (12)
1. A working enclosure adapted to provide a clean air zone within a potentially hazardous environment, the enclosure comprising a canopy adapted to cover at least a part of a working surface to define therewith a clean air zone, at least one air inlet duct connecting said zone to a supply of clean air, means to monitor the content of the air supplied to said zone, alarm/shut down means responsive to the monitoring means, and means to discharge air from the enclosure to establish a controlled operating air pressure within the enclosure which is above ambient pressure outside of the canopy.
2. A working enclosure according to Claim 1, wherein the discharge means is a duct having a diameter less than that of the clean air inlet duct.
3. A working enclosure according to Claim 1, wherein the operating air pressure within the enclosure is controlled within the range of 0.1 to 0.3 bar above ambient pressure outside of the canopy.
4. A working enclosure according to Claim 1, including an air lock in the canopy wall to enable operator access without substantially affecting the operating air pressure within the canopy.
5. A working enclosure according to Claim 1, including means to direct air circulation around the interior of the canopy thus to ensure substantially complete scavenging of any contaminant gases therefrom.
6. A working enclosure according to Claim 1, wherein the canopy is in the form of a flexible shroud supported by a frame and having a peripheral skirt adapted to locate closely against the working surface.
7. A working enclosure according to Claim 1, wherein the canopy has a non-flammable internal surface.
8. A working enclosure according to Claim 1, wherein the canopy is disposed upright, supported by rigging ropes.
9. A working enclosure according to Claim 1, wherein the air inlet duct includes an open end to which is connected a fan supplying the air through the duct into the enclosure, the duct being supported by a frame at its open ends at a position remote from the canopy.
10. A working enclosure according to Claim 1, wherein the alarm/shut down means is adapted to shut down the supply of power to hot-work tools when used within the enclosure.
11. A working enclosure according to claim 1, wherein the canopy is in the form of a rigid pre-shaped enclosure.
12. A working enclosure according to Claim 1, including a plurality of magnetic pads attached peripherally to the canopy to maintain it in close proximity with the working surface.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0128534A GB2382593B (en) | 2001-11-29 | 2001-11-29 | A working enclosure |
| CA002426638A CA2426638C (en) | 2001-11-29 | 2003-04-25 | A working enclosure |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0128534A GB2382593B (en) | 2001-11-29 | 2001-11-29 | A working enclosure |
| CA002426638A CA2426638C (en) | 2001-11-29 | 2003-04-25 | A working enclosure |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2426638A1 CA2426638A1 (en) | 2003-11-05 |
| CA2426638C true CA2426638C (en) | 2005-01-11 |
Family
ID=32714155
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002426638A Expired - Fee Related CA2426638C (en) | 2001-11-29 | 2003-04-25 | A working enclosure |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2426638C (en) |
| GB (1) | GB2382593B (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7518484B2 (en) | 2003-03-13 | 2009-04-14 | Alford Safety Services, Inc. | Enclosure system allowing for hot work within the vicinity of flammable and combustible material |
| US7193501B1 (en) | 2003-03-13 | 2007-03-20 | Alford Safety Services, Inc. | Enclosure system allowing for hot work within the vicinity of flammable and combustible material |
| US7091848B2 (en) | 2003-03-13 | 2006-08-15 | Alford Safety Services, Inc. | Enclosure system for hot work within the vicinity of flammable or combustible material |
| GB0820991D0 (en) * | 2008-11-17 | 2008-12-24 | Safehouse Habitats Scotland Ltd | Control system |
| US8947249B1 (en) | 2009-03-26 | 2015-02-03 | Safezone Safety Systems, LLC | Apparatus and method for conducting hot work |
| DE102011012962A1 (en) * | 2011-03-04 | 2012-09-06 | Audi Ag | Control house structure in doorway of industrial plant, has air pipeline which is led into ground and set in heat exchanger arrangement, where air is delivered for heating or cooling process based on temperature of ground and pipeline wall |
| GB2499469A (en) * | 2012-02-15 | 2013-08-21 | Safehouse Habitats Scotland Ltd | Control System for a Hot Work Habitat |
| US10518301B1 (en) | 2015-12-18 | 2019-12-31 | SafeZone Safety Systems, L.L.C. | Isolation enclosure and method for conducting hot work |
| DE102017000605A1 (en) | 2017-01-24 | 2018-07-26 | Henning Gramann | Apparatus for collecting and discharging waste materials |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3874754A (en) * | 1972-11-27 | 1975-04-01 | Kewaunee Scient Equipment Corp | Biohazard safety cabinet |
| GB2043737A (en) * | 1978-12-15 | 1980-10-08 | Rfd Mills Equipment Ltd | Refuges for use in hazardous environments |
| GB2106160A (en) * | 1981-09-22 | 1983-04-07 | Airborne Ind | Collapsible anti contamination shelter |
| GB2121950B (en) * | 1982-06-04 | 1985-09-04 | Nader Dadabhoy Daroga | Nuclear blast and fall-out shelter |
| FR2541945B1 (en) * | 1983-03-04 | 1987-08-21 | Loubet Eliane | AIR CONDITIONER FOR WORKING CABINS IN POLLUTED ATMOSPHERE |
| GB2233441A (en) * | 1989-05-22 | 1991-01-09 | Hortotec | A clean air cabinet |
| GB2311847A (en) * | 1996-03-30 | 1997-10-08 | E M & I | A working enclosure |
-
2001
- 2001-11-29 GB GB0128534A patent/GB2382593B/en not_active Expired - Fee Related
-
2003
- 2003-04-25 CA CA002426638A patent/CA2426638C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| GB2382593A (en) | 2003-06-04 |
| GB2382593B (en) | 2005-06-22 |
| GB0128534D0 (en) | 2002-01-23 |
| CA2426638A1 (en) | 2003-11-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |
Effective date: 20220301 |
|
| MKLA | Lapsed |
Effective date: 20200831 |