US3711993A - Relatively short air lock for transfer of relatively long objects - Google Patents

Abstract

An air lock has a pair of shutters with variable apertures defining a chamber between a pair of independent spaces. The shutters are flexible and snugly sealingly engageable around an elongated object, and the chamber can be flushed out. The first shutter is closed around the object which is then axially advanced through the second shutter which closes snugly around it. Then the chamber is flushed and the object is axially advanced fully on through the chamber with the shutters closed behind it. The chamber is also flushed during at least one other stage of the operation when one of the shutters is engaged around the object and the other is fully closed, for a unidirectional seal. Three flushings can make a bidirectional seal. The shutters can be annular membranes which are distorted or inflated to engage around the object.

Description

United States Patent Liesch et al. 1 Jan. 23, 1973 54 RELATIVELY SH RT AIR L CK FOR "2335 72 "5/15 5? fiti' i'il .1; zs1;; 1

2,695,605 11/1954 Gibbon ..25l 0F RELATIVELY LONG 1,709,494 4/1929 Rasmussen et al. .....25l/5 X J 1,721,039 7/1929 Risher ..49/68 X 75 Inventors: Jean Liesch, ESch/Ahene; Jacques 3,567,578 3/1971 Isaac ..l76/30 Removille, Steinfort, both of Luxembourg Primary Exammer--Kenneth Downey Attorney-Karl F. Ross [73] Assignees: Acieries Reunies de Burbach-Eich- Dudelange S.A., Arbed; Grade! S.A., [57] ABSTRACT Socleie Luxenibourgeime pour An air lock has a pair of shutters with variable aperdustrle Nucleaire, Stemfort, Luxembourg tures defining a chamber between a pair of independent spaces. The shutters are flexible and snugly [22] Filed: March 15, 1971 sealingly engageable around an elongated object, and the chamber can be flushed out. The first shutter is [21] 124l72 closed around the object which is then axially advanced through the second shutter which closes snugly 30 Foreign Application p i Data around it. Then the chamber is fllushed and the object is axially advanced fully on through the chamber with March 17,1970 Luxembourg ..6 0.542 the Shutters closed behind it The chamber is also flushed during at least one other stage of the operation [52] US. Cl ..49/68, 176/30 when one f the Shutters is engaged around the object [5 1] Int. Cl. and the other is closed for a unidirectionai eaL Field of Search Three flushings can make a bidirectional seal. The 214/13 32 shutters can be annular membranes which are distorted or inflated to engage around the object. [56] References Cited 8 Claims, 21 Drawing Figures UNITED STATES PATENTS 3,501,213 3/1970 Trexler ..49/68 x r 0/ /'/J 7 J/ "l; UNCONTAMINATED f; CONTAMINATED PATENTEUJAH 23 I975 SHEET 1 BF 3 FIG.IC

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JEAN LIESCIH JACQUES REIMOVILLE mvemogs BY qwl ATTORNEY RELATIVELY SHORT AIR LOCK FOR TRANSFER OF RELATIVELY LONG OBJECTS FIELD OF THE INVENTION The present invention relates to an air lock. More particularly, this invention concerns an air lock usable in nuclear installations for the transfer of elongated objects from a contaminated to a noncontaminated space and vice versa.

BACKGROUND OF THE INVENTION It is often necessary to transfer an object through a partition between two independent spaces while preventing any exchange of atmosphere in at least one direction across this partition. Many testing and chemical or biological processes require air locks for this purpose. In addition, it is absolutely necessary to provide such a transfer port in any installation wherein radioactivity is a hazard.

Many different solutions have been tried:

A conventional double-door air lock wherein one door is opened, the object introduced into the lock, this door closed, the atmosphere purged, and then the other door opened and the object removed after which this other door is closed and the atmosphere is again purged was long considered the only solution. Such a lock can be used with only one purging per operating cycle, eliminating the purge after loading the object, when unidirectional leakage is permissible. These devices have one principal drawback: they must be large enough to fully receive the object to be transferred. This makes them very expensive and often so large as to be impractical.

This size disadvantage has been overcome by a system using a sealed polyvinyl chloride bag or a bellows-type air lock both of which make excellent seals, but which are fragile and difficult in the extreme to operate. Another solution has been by means of an air curtain which provides a dynamic or unidirectional seal. Air speeds of at least 1.0 meters per second are necessary, however, so that extremely large-capacity blowers or compressors are required, and even so the resultant turbulence created on the passage of a disadvantageously shaped object can cause leakage in the wrong direction. Air-curtain arrangements thus are expensive to make and unsure in operation.

OBJECTS OF THE INVENTION It is therefore an object of the present invention to provide an improved air lock.

Other objects are the provision of an air lock of small size and low construction cost, and the simplification of the operation of such a lock.

Yet another object is to provide a small air lock through which objects of an overall length many times greater than the air-lock size can be passed.

A further object is the provision of an air lock which is easy to repair.

SUMMARY OF THE INVENTION The above objects are attained according to the present invention by an air lock having a pair of flexible shutters which are axially spaced apart by a distance shorter than the length of the object to be passes through the lock and which can tightly surround and hug the object as it is passed through, and means for flushing out the chamber formed between the shutters.

Such an air lock, according to another feature of the invention, is operated by a very simple method: The first shutter is fitted around one end of the object and the chamber is flushed out, then the object is advanced and the second shutter is fitted around it and the chamber is flushed out again. As the training end finally is pulled through the first shutter, this is closed and the chamber is flushed out again after which the object can be pulled all the way through. In this manner no leakage can take place in either direction. Of course, if a unidirectional seal is sufficient, either the first or last flushing operation, depending on which way the seal is to be effective, can be eliminated.

In accordance with another feature of the present invention the air lock is provided with a rigid door adjacent each shutter so that when the lock is not in use the doors can be latched shut to maintain a heavy-duty static seal. Each door is fixed with its shutter on a mounting ring which is removably mounted on the partition in order that either shutter can be replaced without running the risk of leakage since the other shutter and door are more than capable of maintaining a tight seal.

According to yet another feature of this invention, each shutter is formed by a flexible annular membrane having a pair of ends attached to mutually rotatable rings so that the torsion created in the membrane can close the aperture through its center. The membrane can be formed as a pair of hyperboloids of revolution whose inner peripheries are joined and whose outer peripheries are attached to the adjusting rings. The inner peripheries thus form the aperture. According to another feature of this invention, the membrane can be annular and inflatable so that its internal pressure determines the aperture size.

DESCRIPTION OF THE DRAWING The above and other objects, features and advantages will become apparent from the following description, reference being made to the accompanying drawing, in which:

FIGS. 1A and 1B are side sectional views of a first embodiment of the membrane in the open and closed positions, respectively;

FIG. 1C is a perspective view of the first embodiment of the membrane in the open position;

FIG. 1D is a front elevational view showing the first embodiment of the membrane in the closed position;

FIGS. 1E and IF, FIGS. 10 and 1H, and FIGS. II and U are side sectional views through second, third and fourth embodiments of the membrane according to the present invention, respectively, in the open and closed positions;

FIG. 2 is a side sectional view through an air lock according to the present invention;

FIGS. 3A through 3I are diagrammatic sectional views illustrating the method of operating the air lock according to the present invention; and

FIG. 4 is a diagrammatic side sectional view through another embodiment of the present invention.

SPECIFIC DESCRIPTION As seen in FIGS. lA-lD, a membrane 1 is formed with two portions 1' and 1" each shaped as hyperboloids of revolution and joined at their inner periphery. The outer peripheries of the portions 1' and l" are joined to mutually rotatable adjacent rings 2' and 2", respectively. An actuating member 14 extends radially out from the ring 2" and serves to rotate this ring relative to the other to move the membrane from the open position shown in FIGS. 1A and 1C to the closed position of FIGS. 18 and 1D.

FIGS. 1E and IF show a seal 3 which is highly flexible and hollow. Its interior is connected to a compressor 17 so that as the internal pressure is increased, its inner edge 30 can be brought radially into engagement around an elongated workpiece 5 of convex cross-sectional shape and regular cross section. This annular membrane 3 is formed at its inner periphery 3a with a plurality of circumferential ridges to form a very good seal around the object 5.

In FIGS. 1G and 1H, there is shown a membrane 4 which is formed by a central highly elastic ring 4a connected via a pair of annular flexible membranes 4a and 4b to a pair of rings 2a and 2a" which are axially displaceable toward each other. When the rings 2a and 2a are separated as in FIG. 1G, the aperture formed by the ring 4a is open, and when they are brought toward each other as in FIG. ll-I, this aperture decreases in size to snugly hug the body 5.

The membrane 18 shown in FIGS. ll and l] is essentially cylindrical in shape and has its ends attached to relatively rotatable rings 2b and 2b" such that their mutual rotation determines the size of the aperture through the membrane 18.

FIG. 2 shows a partition wall 19 of concrete sheathed by steel plate which separates an uncontaminated space 7 from a radioactively contaminated space 8. A passage or part 6 is formed through this partition 19 with angle rings 9 and 9' seated in its opposite ends and held in place by means of dogs 13 carried on bolts 13a. The rings 9 and 9' are sealed by means of seal rings 20 and each carry further annular mounting members 21 in which is received a rotatable ring 10. A door 12 hinged at the top is provided on one of the rings 21 and a similar door 12' is provided on the other. Pivotal latches 22 are provided to hold these doors l2 and 12 in tight engagement with seal rings 23 carrying resilient seals 24 so that the passage 6 can be a gastight chamber. Adjacent each of the doors l2 and 12' is a respective membrane 11 and 11, such as described with reference to FIGS. lA-lD. Here the two mutually rotatable rings are constituted by the rings 21 and 10. These membranes 11 and 11' are shown in the closed position in FIG. 2.

A pair of conduits and 16 open into the chamber 6. The conduit 16 leads to a filter 25 which is connected to a pump 26 that is itself connected to the conduit 15. In this manner the atmosphere in the chamber 6 can be flushed or purged, with any radioactive particles therein trapped in the filter 25, which can be electrostatic or of the activated-carbon type. Of course, if a substantial pressure differential exists across the partition 19 the pressure in the chamber 6 will have to be maintained above that on the side from which no contamination is permissible. For a bidirectional seal, the

pressure in the chamber 6 must be lower or higher than that to both sides. To do this the flow path must be interrupted somewhere and opened to the atmosphere.

A control 29 connected to pressure sensors 27 and 28 in chambers 7 and 8, respectively, is coupled to the pump 26 to create a pressure differential across either of the shutters. Of course, a pressure differential is often created as a matter of course between contaminated and noncontaminated spaces so that dust leakage is made virtually impossible. This, the pressure in the chamber 6 can be maintained at an intermediate level by the control 29 for the best seal.

It is also possible to use seals which do not close fully, but merely have an aperture adjustable around the size of the objects intended to pass through the air lock. In such an arrangement, the doors forming a static seal are absolutely necessary, and it is advantageous to arrange the pressure differentials across the shutters, which can be thought to include the doors, to prevent leakage in the wrong direction.

The latches 13, doors 12 and 12, and membranes 11 and 1 1 can all be controlled by remote control through a control device 30, which functions synchronously with the displacement of the object 5 through the air lock.

FIGS. 3A-3I show the operation of the air lock shown in FIG. 2. In FIG. 3A it is shown how both doors l2 and 12 and both membranes 11 and 11' are closed so that in effect four barriers exist between the space 7 and the space 8. In FIGS. 38 the door 12 and the corresponding membrane ll are opened and the leading end of the body 5 is inserted in the aperture, with any pressure differential compensated for by the control 29. FIG. 3C shows how this body 5 has been axially advanced so that its leading end is fully within the chamber 6 and the membrane 11 has been snugly closed around the body 5. At this stage, the pump 26 is actuated to flush out the chamber 6 if a bidirectional seal is desired and to establish the same pressure as in the contaminated zone. If, however, the only aim is to prevent the radioactivity in space 8 from getting into the space 7 then there is no necessity for this flushing.

In FIG. 3D the body 5 has been axially advanced further so that its leading edge extends beyond the membrane 11 and door 12, both of which are now open. Thereafter, as seen in FIG. 3E this membrane 1 l is closed around the body 5 and the compartment 6 is flushed out. This flushing operation is necessary for a bidirectional seal.

FIG. 3F shows how the body 5 has been advanced so that its trailing edge is within the chamber 6 and in FIG. 3G the door 12 and membrane 11 are closed and the chamber is flushed out. In FIG. 3H the rod 5 has been advanced fully out of the air lock and in FIG. 3I all doors l2 and 12' and shutters l1 and 11" are shut and the chamber 6 is flushed.

If leakage can occur, as seen in FIGS. 3A-3I, from left to right the chamber need only be flushed in the positions shown in FIGS. 3 E and 3|. If leakage in the other direction is permissible the chamber 6 need only be flushed in the positions shown in FIGS. 3C and 3G. Of course, as described above, flushing is necessary in the positions of FIGS. 3C, 3E, 3G and 31 for a bidirectional seal. In any case, the flushing of FIG. 3E or of FIG. 3I is necessary and one flushing when one end of the object is in the chamber while it is gripped by one of the shutters and the other shutter is closed is necessary.

FIG. 4 shows a further embodiment of the invention wherein three shutters 11, l1 and ll" are provided, together defining two chambers 6 and 6" separately flushable by conduits l5, l6 and 16" respectively. This embodiment is used as taught for the embodiment of FIGS. 3A-3', except that the second chamber is used to make an extremely tight seal. Similarly four or more shutters can be used, the leak protection being increased thereby as well as the ability to withstand large pressure differentials.

The air locks described above can be used in the walls of nuclear installations for the transfer of fuel elements and the like, or in the walls ofa glove box. These locks permit the passage of a relatively long object through a relatively thin wall so that, for instance, a fuel element some 4 feet long can be passed through a wall 6 inches thick. The saving in space is large. At the same time, either side of the lock can be unscrewed and replaced without in any manner risking leakage. After the new side is put in place and closed the chamber need merely be flushed to insure complete tightness.

We claim:

1. An air lock for the passage of an elongated object between two independent and adjacent spaces, said air lock comprising:

means defining a cylindrical chamber between said spaces of a length greater than its diameter, said means including a pair of circular shutters at opposite sides of said chamber and interposed between the latter and a respective one of said spaces, each of said shutters being annular flexible membranes and openable from the center outwardly to produce respective axially aligned variable-size apertures surrounding and hugging the object upon its axial insertion therethrough;

means for introducing a fluid into said chamber and for withdrawing a fluid therefrom; and

a respective rigid door engageable over each of said shutters and forming a tight seal for said chamber independently of the respective shutter.

2. The air lock defined in claim 1 wherein each of said membranes has in an open position the form of a pair of hyperboloids of revolution joined at their inner peripheries.

3. The air lock defined in claim 1 wherein said membrane is hollow, said air lock further comprising means for inflating said membrane and thereby changing the dimensions of said aperture.

4. The air lock defined in claim 1, further comprising a removable mounting body carrying said door and its shutter.

5. A method of operating an air lock having a pair of shutters defining a chamber between a pair of adjacent independent spaces, said method comprising the steps of:

axially advancing an elongated object into said chamber past a first one of said shutters until its leading end lies between said shutters;

closing said first shutter snugly around said object while closing the chamber opposite said first shutter;

opening the second of said shutters; axially advancing said ob ect through said chamber until its leading end passes beyond said second shutter while maintaining said first shutter in snug sealing contact around said object;

closing said second shutter snugly around said object;

flushing said chamber with a fluid;

axially advancing said object unit its trailing end lies between said shutters while maintaining said second shutter in snug sealing contact around said object;

closing the chamber in the region of said first shutter;

flushing said chamber with a fluid while one of said ends of said object lies between said shutters with said second shutter sealingly engaged around said object and the first shutter of the chamber fully closed; and

axially advancing said object out of said chamber.

6. The method defined in claim 5 wherein, in order to have a bidirectionally effective seal, said chamber is flushed when said leading end lies between said shutters with said first shutter snugly engaging around said object and said second shutter fully closed and when said trailing end lies between said shutters with said second shutter snugly engaging around said object and said first shutter fully closed.

7. The method defined in claim 5 wherein said air lock has a rigid door to each side of said chamber adjacent each of said shutters, said method further comprising the steps of:

opening the door adjacent said first shutter prior to axially advancing said leading end into said chamber;

opening the door adjacent said second shutter prior to openingsaid second shutter; and

closing both of said doors after axially advancing said object completely out of said chamber.

8. The method defined in claim 5, further comprising the step of maintaining a pressure differential across at least one of said shutters in a closed condition thereof.

Claims (8)

1. An air lock for the passage of an elongated object between two independent aNd adjacent spaces, said air lock comprising: means defining a cylindrical chamber between said spaces of a length greater than its diameter, said means including a pair of circular shutters at opposite sides of said chamber and interposed between the latter and a respective one of said spaces, each of said shutters being annular flexible membranes and openable from the center outwardly to produce respective axially aligned variable-size apertures surrounding and hugging the object upon its axial insertion therethrough; means for introducing a fluid into said chamber and for withdrawing a fluid therefrom; and a respective rigid door engageable over each of said shutters and forming a tight seal for said chamber independently of the respective shutter.

2. The air lock defined in claim 1 wherein each of said membranes has in an open position the form of a pair of hyperboloids of revolution joined at their inner peripheries.

3. The air lock defined in claim 1 wherein said membrane is hollow, said air lock further comprising means for inflating said membrane and thereby changing the dimensions of said aperture.

4. The air lock defined in claim 1, further comprising a removable mounting body carrying said door and its shutter.

5. A method of operating an air lock having a pair of shutters defining a chamber between a pair of adjacent independent spaces, said method comprising the steps of: axially advancing an elongated object into said chamber past a first one of said shutters until its leading end lies between said shutters; closing said first shutter snugly around said object while closing the chamber opposite said first shutter; opening the second of said shutters; axially advancing said object through said chamber until its leading end passes beyond said second shutter while maintaining said first shutter in snug sealing contact around said object; closing said second shutter snugly around said object; flushing said chamber with a fluid; axially advancing said object unit its trailing end lies between said shutters while maintaining said second shutter in snug sealing contact around said object; closing the chamber in the region of said first shutter; flushing said chamber with a fluid while one of said ends of said object lies between said shutters with said second shutter sealingly engaged around said object and the first shutter of the chamber fully closed; and axially advancing said object out of said chamber.

6. The method defined in claim 5 wherein, in order to have a bidirectionally effective seal, said chamber is flushed when said leading end lies between said shutters with said first shutter snugly engaging around said object and said second shutter fully closed and when said trailing end lies between said shutters with said second shutter snugly engaging around said object and said first shutter fully closed.

7. The method defined in claim 5 wherein said air lock has a rigid door to each side of said chamber adjacent each of said shutters, said method further comprising the steps of: opening the door adjacent said first shutter prior to axially advancing said leading end into said chamber; opening the door adjacent said second shutter prior to opening said second shutter; and closing both of said doors after axially advancing said object completely out of said chamber.

8. The method defined in claim 5, further comprising the step of maintaining a pressure differential across at least one of said shutters in a closed condition thereof.

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