GB2102527A - Door structure for pressurized enclosure - Google Patents

Abstract

A pressurized enclosure has a hinged door (4) which can be latched closed against a seal (18) by a lever (24) clamping behind a wall portion (12). To retain the door closed against distortion of the enclosure under pressure, the door and the wall portion have opposed limit surfaces (28, 30) limiting relative movement of the latch lever and the wall portion. <IMAGE>

Description

SPECIFICATION Door structure for pressurized enclosure The invention relates to a door structure for a pressurized enclosure. Electrical equipment for use in the vicinity of explosive gases or vapours, and capable of producing a spark which might ignite such gases or vapours, is confined within an enclosure containing a non-ignitable gas and maintained at a super-ambient pressure so that the ignitable gas or vapour cannot enter. Such enclosures, which may be fitted with pressure relief valves of the kind disclosed in Patent Specification GB 1 593 871, are typically rectangular in plan with sides and height of the order of one and two metres respectively. A latchable door is required to permit access to the equipment and this conveniently occupies substantially the whole of one side of the enclosure.The walls, door and roof of the enclosure can be made of sheet metal and are consequently subject to distortion under the excess pressure they experience which may be of the order of 1/2 p.s.i. The distortion can be so great as to render the latching arrangements ineffective, so that the door opens under the excess internal pressure and the area in which the electrical equipment operates is no longer safe. Such distortion can be avoided by measures to impart adequate structural rigidity to the enclosure but only with expenditure of reinforcing material and consequential extra expense.

The invention is accordingly concerned with the provision of a door structure for a pressurized enclosure by which this difficulty is overcome.

The invention accordingly provides a door structure for a pressurized enclosure in which the door has at the edge thereof opposite the hinged edge, fastener means engaging an inwardly facing latching surface of the door jamb, and opposed surfaces on the door and the jamb normally spaced apart but engageable on deformation of the enclosure due to super-ambient pressure therein to limit relative movement of the fastener means and the latching surface so as to ensure that the door is held closed.

Conveniently the door is formed as a metal panel shaped along its free side with a portion turned through 180 and providing one of the limit surfaces at the free edges. The door jamb can also be constituted by the end of a metal panel forming a side wall perpendicular to the door panel when the latter is closed, this end portion being shaped through 900to provide the latching surface and being shaped beyond this surface to provide the other limit surface, or to support an additional element providing it, and also to mount a sealing member engageable with the closed door. It will be evident that a variety of other configurations are possible, even with enclosures constructed primarily of sheet metal, all providing enhanced security against accidental unlatching of the door of a pressurized container in a simple and inexpensive way.

A door structure embodying the invention is further described below, by way of example, with reference to the accompanying drawing, the single figure of which is a fragmentary sectional plan view of the corner of a pressurized enclosure at which the free end of the door of the structure engages the jamb.

The pressurized enclosure illustrated is generally square or rectangular in plan and has a height greater than the length of its side or sides. Three side walls, of which one side wall 2 is shown, and the roof are constructed of metal sheet. The fourth wall is constituted by a door 4 hinged on a vertical pivot axis for outward opening at the vertical edge of the side wall opposite the wall 2. The free edge of the door 4 is sealed against the wall 2 and is latched to it by arrangements described below.

As appears from the drawing, the door 4 comprises a sheet metal panel 6 formed at its free edge with an integral portion 8 turned inwardly at right angles and ending with a lip portion 10 turned back towards the hinged edge of the door. The wall 2 has at its edge towards the door a portion 12 turned at right angles towards the door hinges, a secured portion 14 at right angle towards the door, and finally an end portion 16 parallel to and overlying the portion 12, but extending short of it. The portion 16 of the wall 2 adhesively mounts a seal 18 of rubber or flexible plastics material having a compressible hollow bead portion 20 which is engaged and deformed by the door panel 6 as shown, in the closed position of the door, to provide a wide sealing face with the panel.

The door 4 can be latched in the closed position by a fastener comprising a shaft 22 which may be turned on its axis to rotate about the axis a radially projecting lever 24, between the closed position shown, in which the free end of the lever clamps behind the wall portion 12, and an open position free of this portion. The shaft 22 may be operated manually or by a key or other tool; the fastener illustrated will usually be one of a plurality of such fasteners spaced vertically along the door 4 and linked to operate together.

It will be appreciated that the excess pressure within the enclosure will act on the door 4 and the wall 2 in the directions of the arrows of the leading lines associated with the reference numerals and if the resultant distortion is sufficient, the overlap of the lever 24 on the portion 12 will disappear and the door will burst open. To prevent such an occurrence, the wall 2 has secured thereto, by means of screws 25 extending through apertures in the portion 14, an element 26 in the form of a metal square section bar received in the corner between the wall portions 12 and 14. The element 26 provides a surface 28 opposed to the free end surface 30 of the door portion 10.The spacing at 32 between these surfaces 28,30 at zero excess pressure represents the maximum possible extent of outward movement of the wall 2 under the internal pressure and provided this is substantially less than the overlap between the lever 24 and the side wall portion 12 at the time, the wall movement under subsequent internal pressure cannot adversely affect the integrity of the latching effected by the fastener.

The bar 26 can extend along the whole length of the free edge of the door 2 or a shorter length of such a bar can be provided in the vicinity of the or each fastener lever 24. The opposing surfaces 28,30 can of course be provided for by a variety of different configurations of the door and jamb.

CLAIMS (Filed 21 July 1982) 1. A pressurized enclosure comprising wall means, a door for closing an aperture in the wall means, interengageable latch means on the door and wall means, and limit surfaces interengageable on deformation of the enclosure due to superambient pressure therein to limit relative movement of the latch means towards disengagement to thereby hold the door closed.

2. A pressurized enclosure as claimed in claim 1 wherein the limit surfaces comprise surfaces on the door and wall means respectively which are spaced apart in the absence of the enclosure deformation.

3. A pressurized enclosure as claimed in claim 1 or 2 wherein the latch means comprises a latch lever carried by the door and pivotable to engage a fixed latch surface on the wall means.

4. A pressurized enclosure as claimed in claim 1, 2 or 3 wherein the door is hinged at one edge thereof to the wall means.

5. A pressurized enclosure comprising wall means, a door for closing an aperture in the wall means, and fastener means for latching the door in the closed position, the fastener means comprising a movable latch element engageable with a latch surface, and opposed limit surfaces on the door and the wall means normally spaced apart but engageable on deformation of the enclosure due to superambient pressure therein to limit relative movement of the latch element and latch surface so as to ensure that the door is held closed.

6. A pressurized enclosure as claimed in claim 5 having hinge means connecting a first edge of the door to the wall means, the fastener means being located at a door edge opposite the first edge.

7. A pressurized enclosure as claimed in claim 6 wherein the door is of metal sheet construction and the limit surface thereof is provided by an edge of an integrally formed portion of the door.

8. A pressurized enclosure as claimed in claim 5, 6 or 7 wherein the door mounts the movable latch element and the latch surface is a surface of a jamb portion of the wall means, which portion is continued beyond the latch surface to provide the enclosure limit surface.

9. A pressurized enclosure as claimed in claim 8 wherein the jamb portion is turned through a right angle from the latch surface to receive within the angle a member of which a surface constitutes the limit surface.

10. A pressurized enclosure as claimed in claim 8 or 9 wherein the enclosure wall portion is continued beyond the limit surface to mount seal means engageable with the door inner surface.

11. A pressurized enclosure as claimed in claim 8,9 or 10 wherein the enclosure wall is of metal sheet construction, the jamb portion being an integrally formed portion thereof.

12. A pressurized enclosure substantially as herein described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (12)

**WARNING** start of CLMS field may overlap end of DESC **. fastener lever 24. The opposing surfaces 28,30 can of course be provided for by a variety of different configurations of the door and jamb. CLAIMS (Filed 21 July 1982)

1. A pressurized enclosure comprising wall means, a door for closing an aperture in the wall means, interengageable latch means on the door and wall means, and limit surfaces interengageable on deformation of the enclosure due to superambient pressure therein to limit relative movement of the latch means towards disengagement to thereby hold the door closed.

2. A pressurized enclosure as claimed in claim 1 wherein the limit surfaces comprise surfaces on the door and wall means respectively which are spaced apart in the absence of the enclosure deformation.

3. A pressurized enclosure as claimed in claim 1 or 2 wherein the latch means comprises a latch lever carried by the door and pivotable to engage a fixed latch surface on the wall means.

4. A pressurized enclosure as claimed in claim 1, 2 or 3 wherein the door is hinged at one edge thereof to the wall means.

5. A pressurized enclosure comprising wall means, a door for closing an aperture in the wall means, and fastener means for latching the door in the closed position, the fastener means comprising a movable latch element engageable with a latch surface, and opposed limit surfaces on the door and the wall means normally spaced apart but engageable on deformation of the enclosure due to superambient pressure therein to limit relative movement of the latch element and latch surface so as to ensure that the door is held closed.

6. A pressurized enclosure as claimed in claim 5 having hinge means connecting a first edge of the door to the wall means, the fastener means being located at a door edge opposite the first edge.

7. A pressurized enclosure as claimed in claim 6 wherein the door is of metal sheet construction and the limit surface thereof is provided by an edge of an integrally formed portion of the door.

8. A pressurized enclosure as claimed in claim 5, 6 or 7 wherein the door mounts the movable latch element and the latch surface is a surface of a jamb portion of the wall means, which portion is continued beyond the latch surface to provide the enclosure limit surface.

9. A pressurized enclosure as claimed in claim 8 wherein the jamb portion is turned through a right angle from the latch surface to receive within the angle a member of which a surface constitutes the limit surface.

10. A pressurized enclosure as claimed in claim 8 or 9 wherein the enclosure wall portion is continued beyond the limit surface to mount seal means engageable with the door inner surface.

11. A pressurized enclosure as claimed in claim 8,9 or 10 wherein the enclosure wall is of metal sheet construction, the jamb portion being an integrally formed portion thereof.

12. A pressurized enclosure substantially as herein described with reference to the accompanying drawing.