The present disclosure relates to a hot changeover apparatus used in an optical fibre drawing furnace and more particularly, relates to the hot changeover apparatus incorporating a sealing mechanism and a cooling mechanism for the optical fibre drawing furnace.
BACKGROUND
[0002] In general, a hot changeover apparatus is used in an optical fibre drawing furnace. The optical fibre drawing furnace operates at a temperature of 2000-2500 degree Celsius for drawing of an optical fibre from an optical fibre preform. In other words, a high temperature heat source is required for drawing a high strength and low loss optical fibre from the optical fibre preform. An exemplary predominant heat source utilized for drawing the optical fibre are graphite furnaces. The graphite furnaces may include a graphite muffle where the graphite muffle is insensitive to rapid changes in temperature and thus is less susceptible to cracking. It has been found, however, that graphite furnaces are susceptible to oxidation at temperatures approaching about 450°C and that oxidation is particularly problematic. Some of the prior art references are given below:
[0003] WO2012053394A1 proposes a sealing structure/ mechanism for sealing drawing furnace but the sealing structure/ mechanism does not support twin function of sealing and cooling of hot drawing furnace.
[0004] WO2020157769A1 proposes a drawing process to prevent mixing of core and clad but has a limitation as it lacks lowering down of drawing furnace temperature, which gets heated during drawing of fibre. The process lacks usage of a combination of sealing and cooling mechanism for the drawing furnace.
[0005] WO2012033158A1 discloses a sealing structure, where the sealing structure may be adjusted as per a diameter of an optical fibre preform in order to seal furnace during drawing of optical fibre of every diameter but lacks to explain cooling system for a hot furnace. Thus, the sealing structure lacks usage of a combination of sealing and cooling mechanism for drawing furnace.

[0006] EP1159228Al teaches a sealing structure to prevent oxidation of graphite furnace inside the drawing furnace due to interaction of atmospheric gases with graphite rods, but lacks to explain a mechanism to lower down the temperature of heated drawing furnace. Thus, the sealing structure lacks usage of a combination of sealing and cooling mechanism for drawing furnace.
[0007] While the prior arts cover various techniques for sealing mechanism for the drawing furnace, however, these solutions are not effective, since existing methods and systems have drawbacks such as huge time consumption (or high waiting time) during changeover from one to next preform during optical fibre drawing process, oxidization problem in carbon/graphite tubes inside the drawing furnace, for example. In light of the above-stated discussion, there is a need to overcome the above stated disadvantages.
OBJECT OF THE DISCLOSURE
[0008] A principal object of the present disclosure is to provide a hot changeover apparatus that includes a plurality of plates functioning for/as a sealing mechanism and a cooling mechanism for an optical fibre drawing furnace (interchangeably "drawing furnace" or "furnace").
[0009] Another object of the present disclosure is to reduce waiting time for loading of next optical fibre preform during a drawing process using the hot changeover apparatus, thereby increasing quantity of manufactured optical fibre.
[0010] Another object of the present disclosure is to improve furnace working life/period as cooling of the furnace allows graphite tubes to work more without oxidising easily.
SUMMARY
[0011] Accordingly, the present disclosure provides a hot changeover apparatus for use in an optical fibre drawing furnace. The hot changeover apparatus is rectangular in shape. The hot changeover apparatus comprises an openable shutter system arranged near a top portion of the optical fibre drawing furnace and a cooling system for cooling the optical fibre drawing furnace. The

cooling system comprises a body having one or more coolant channels. The openable shutter system allows a passage of an optical fibre preform in an open configuration and the openable shutter system performs a sealing mechanism for the optical fibre drawing furnace in a closed configuration. The openable shutter system allows sealing of the optical fibre drawing furnace in less than five seconds after pulling out of the optical fibre preform from the optical fibre drawing furnace.
[0012] The openable shutter system comprises a circular step at a centre of the hot changeover apparatus, when the hot changeover apparatus is in the closed configuration. The openable shutter system is a pair of semi-circular plates, wherein the pair of semi-circular plates has an arc on its diameter side. The arc on the pair of semi-circular plates forms the circular step in the openable shutter system. The openable shutter system ensures prevention of a conical section of the optical fibre preform from breaking.
[0013] The hot changeover apparatus also includes a plurality of plates that withstands temperature of 2000 degree Celsius and is made of stainless steel. The plurality of plates are stacked one over the other through one or more connecting means, wherein a first plate from the plurality of plates comprises a plurality of rings. The plurality of rings included in the first plate aids in assembling of components to hold the optical fibre preform in the optical fibre drawing furnace.
[0014] A second plate from the plurality of plates has a solid protruded portion in the centre, wherein the solid protruded portion is hollow from inside which aids in flow of water passage and is situated just below the openable shutter system present on the first plate of the plurality of plates. The first plate and a third plate from the plurality of plates ensure fixing of the openable shutter system within the optical fibre drawing furnace.
[0015] A length side of the plurality of plates forms a horizontal portion and a breadth side of the of the plurality of plates forms a vertical portion of the plurality of plates, wherein the length side of the plurality of plates is greater than the breadth side of the plurality of plates. Further, a pair of water connectors is

provided along the length side of the plurality of plates for entry and exit of water and a pair of pneumatic pipes and a water circulation pipes are arranged at the breadth side of the plurality of plates. Each of the pair of water connectors has a first taper at one of an end portion and a second taper inside a water connector.
[0016] These and other aspects herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the invention herein without departing from the spirit thereof.
BRIEF DESCRIPTION OF FIGURES
[0017] The invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the drawings. The invention herein will be better understood from the following description with reference to the drawings, in which:
[0018] FIG. 1 and FIG. 2 illustrate a front view and a top view respectively of one or more plates of a hot changeover apparatus.
[0019] FIG. 3 illustrates a top sectional view representing the one or more plates with a plurality of rings.
[0020] FIG. 4 and FIG. 5 illustrate front sectional views representing a pneumatic pipe operating jaws in a circular step.
[0021] FIG. 6 and FIG. 7 illustrate front sectional views representing the pneumatic pipe connected with a rectangular plate and a spanner.
[0022] FIG. 8 illustrates a sectional view representing a support rod.
[0023] FIG. 9 illustrates a sectional view of a water connector.
[0024] FIG. 10 and FIG. 11 illustrate a front view and a side view of the one or more plates depicting a slot/point for water exit and water entry.
[0025] FIG. 12 to FIG. 14 illustrate a side view representing one or more side plate supports to which a rod (guide) cylinder is connected.

DETAILED DESCRIPTION
[0026] In the following detailed description of the invention, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be obvious to a person skilled in the art that the invention may be practiced with or without these specific details. In other instances, well known methods, procedures and components have not been described in detail so as not to unnecessarily obscure aspects of the invention.
[0027] Furthermore, it will be clear that the invention is not limited to these alternatives only. Numerous modifications, changes, variations, substitutions and equivalents will be apparent to those skilled in the art, without parting from the scope of the invention.
[0028] The accompanying drawings are used to help easily understand various technical features and it should be understood that the alternatives presented herein are not limited by the accompanying drawings. As such, the present disclosure should be construed to extend to any alterations, equivalents and substitutes in addition to those which are particularly set out in the accompanying drawings. Although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are generally only used to distinguish one element from another.
[0029] FIG. 1 and FIG. 2 illustrate a front view and a top view of one or more plates (102-106) of a hot changeover apparatus (100). The hot changeover apparatus (100) is used in an optical fibre drawing furnace (not shown). The optical fibre drawing furnace (interchangeably "drawing furnace" or "furnace") operates at a high temperature (e.g., 1700-2500 degree Celsius or the like) for drawing of an optical fibre from an optical fibre preform. In general, the optical fibre preform is a cylindrical piece of an optical glass such as silica that is used for drawing the optical fibre in a fibre drawing furnace.
[0030] A hot changeover implies a process or act of change of optical fibre preform (or preform) for drawing process once a preform has been drawn up in the drawing furnace. As shown in FIG. 1 and FIG. 2, the hot changeover apparatus (100) is in a rectangular structure/shape. However, based on the

requirement and implementation, the hot changeover apparatus (100) may also be in a square structure, a circular structure, and a hexagon structure. The shape of the hot changeover apparatus (100) does not limit the scope of the present disclosure.
[0031] The hot changeover apparatus (100) may include a plurality of plates (i.e., a top plate (102), a bottom plate (104) and a middle plate (106)). The top plate (102), the bottom plate (104) and the middle plate (106) may be stacked one over the other through one or more connecting means (134), thus may be termed as a plurality of stacked plates (102, 104, 106). The middle plate (106) may be sandwiched between the top plate (102) and the bottom plate (104), wherein each of the top plate (102), the middle plate (106) and the bottom plate (104) has a concentric hole section. The one or more connecting means (134) may be, but not limited to, bolts, screws or the like. In an example, the dimensions of the one or more connecting means is 2*M6, 30deep. Alternatively, the dimensions of the one or more connecting means may vary.
[0032] The top plate (102), the bottom plate (104) and the middle plate (106) may withstand a high temperature around 2000 degree Celsius. The top plate (102), the bottom plate (104) and the middle plate (106) may be made of stainless steel (e.g., austenitic stainless steel, martensitic Stainless Steel, ferritic stainless steel or the like), aluminium or any other suitable material that can withstand such high temperature.
[0033] Further, the top plate (102) (interchangeably "first plate") may comprise a plurality of rings (114) (as shown in FIG. 3). The plurality of rings (114) may act as a support to the optical fibre preform to bear weight of the optical fibre preform. The plurality of rings (114) may be installed at an upper end of the optical fibre drawing furnace. The plurality of rings (114) included in the top plate (102) aids in assembling of components to hold the optical fibre preform in the optical fibre drawing furnace.
[0034] Each plate may have a circular section such that the circular section of each of the plurality of stacked plates (102, 104, 106) is concentric, wherein at least one plate has movable sections to enable an openable shutter system (130)

transition among a closed configuration (explained below), an open configuration (explained below) and a sealing configuration, wherein the sealing configuration is associated with sealing of radial gap between the optical fibre preform and the optical fibre drawing furnace.
[0035] The openable shutter system (130) may be formed by the top plate (102), the bottom plate (104) and the middle plate (106). Further, the openable shutter system (130) may be arranged near a top portion of the optical fibre drawing furnace and may imply jaws having a circular shape, where the openable shutter system (130) may operate through a pneumatic pipe (112). The pneumatic pipe (112) may be connected at a breadth side of the bottom plate (104). The openable shutter system (130) may act as a sealing mechanism (in sealing configuration) and functions as a seal for the optical fibre drawing furnace. Further, the openable shutter system (130) may be provided in the top plate (102) (interchangeably "first plate") which is above the middle plate (106) (interchangeably "second plate").
[0036] The openable shutter system (130) may be formed with the help of a pair of semi-circular jaws (interchangeably "a pair of semi-circular plates" or "one or more moving jaws") having an arc at one side (diameter side) such that the openable shutter system (130) having a circular step (132) at its centre when the openable shutter system (130) is in the closed configuration. In other words, the openable shutter system (130) inside the first plate (102) is a pair of semi¬circular jaws or plates, wherein the pair of semi-circular plate has an arc on its diameter side, wherein the arc on the pair of semi-circular plates forms the circular step (132) in the openable shutter system (130). The pair of semi-circular jaws gets opened/closed through the pneumatic pipe (112). In the open configuration of the openable shutter system (130), the pair of semi-circular jaws may be at a distance apart to provide space for the optical fibre preform inside the furnace. A diameter of each jaw of the pair of semi-circular jaws may be 15 mm (millimeter). Alternatively, the diameter of each jaw may vary.
[0037] Similarly, in the closed configuration, the pair of semi-circular jaws comes together to form a closed space with the arc at the centre of the

openable shutter system (130) such that the openable shutter system (130) seals the optical fibre drawing furnace i.e., shutting off/cutting off atmospheric gas contact with graphite rods present inside the drawing furnace. In the closed configuration, the openable shutter system (130) may act as a seal and may both open and close the pair of semi-circular jaws through the pneumatic pipe (112). The openable shutter system (130) may be closed when the optical fibre preform is being changed or next (subsequent) preform is being loaded for drawing process while the openable shutter system (130) may be kept open when the optical fibre is undergoing drawing process. In other words, the closed configuration may be triggered when the optical fibre drawing furnace is in a heated state and a changeover state. The heated state of the optical fibre drawing furnace is defined by a temperature between 1700-2200 degree Celsius and the changeover state of the optical fibre drawing furnace is associated with exit of residual of a previous optical fibre preform after drawing and before insertion of a subsequent optical fibre preform.
[0038] In short, the openable shutter system (130) may allow a passage of the optical fibre preform (cylindrical glass preform or preform or optical fibre glass preform) in the open configuration and the openable shutter system (130) may perform a sealing mechanism for the optical fibre drawing furnace in the closed configuration. The openable shutter system (130) may enable sealing for the optical fibre drawing furnace when a diameter variation of the optical fibre preform along a preform length is up to 20mm. The bottom plate (104) having the one or more moving jaws helps in transitioning the openable shutter system (130) between the open configuration and the closed configuration.
[0039] Advantageously, the openable shutter system (130) ensures prevention of a conical section of the optical fibre preform from breaking. The top plate (102) and the middle plate (106) (interchangeably "second plate") ensure fixing of the openable shutter system (130) within the optical fibre drawing furnace.
[0040] Further, the middle plate (106) may be provided with a cooling system (108d). The cooling system (108d) may be integrated into the openable

shutter system (130). The cooling system (108d) is formed by a body having one or more coolant channels (e.g., water intake port (108b) and water exit port (108c)). That is, the middle plate (106) may have hollow sections forming the one or more coolant channels (108b, 108c). The cooling system (108d) having the one or more coolant channels (108b, 108c) may bring the optical fibre drawing furnace in a cooled state and in an insertion state in less than 30 mins. The cooled state may be associated with a temperature about 1000 degree Celsius and the insertion state may be associated with insertion of the subsequent optical fibre preform and the open configuration of the openable shutter system (130).
[0041] The water intake port (108b) and the water exit port (108c) may be connected at a length side (along the length) of the middle plate (106) for performing a water intake process and a water exit process, respectively. The flow of water inside the middle plate (106) may act as a medium to transfer heat to a cooling furnace (not shown). The water flowing in the middle plate (106) may act as a medium of heat transfer due to which time for changing the optical fibre preform in the drawing furnace may be reduced from 50 minutes to 20-25 minute, for example.
[0042] In the cooling system, the water (i.e., coolant) may be provided through the water intake port (108b) and is drawn out from the water exit port (108c). The water may transfer heat by circulating it around the middle plate (106) through the water intake port (108b) and the water exit port (108c). In other words, the water may be used as coolant for transferring the heat from the drawing furnace because it has high heat transferring capacity. The water intake port (108b) and the water exit port (108c), each may be provided with a water connector (108a) as well as the pneumatic pipe (112) for cooling and sealing mechanism, respectively. That is, a pair of water connectors (108a) along a length side of the plurality of plates (102-106) may be provided for entry and exit of water, a pair of pneumatic pipes (interchangeably "pneumatic pipe") (112) and a pair of water circulation pipes (136a, 136b) may be arranged at a breadth side of the plurality of plates (102-106). The water connector (or pair of water connectors) (108a) may be present at the middle plate (106) and each of the pair

of water connectors (108a) may comprise a first taper (138a) at one of an end portion and a second taper (138b) inside a water connector (108a) (Shown in FIG. 9) that reduce thickness at the ends of the water connector (108a). The middle plate (106) may have a solid protruded portion in the centre which is hollow from inside through which the water circulates in a circular motion using the pair of water circulation pipes (136a, 136b) for transferring the heat away from the optical fibre drawing furnace. The solid protruded portion may be situated just below the openable shutter system (130) present on the top plate (102). The bottom plate (104) is a solid plate just below the middle plate (106). The purpose of the bottom plate (104) is to provide sufficient strength to the hot changeover apparatus to bear load of the optical fibre preform i.e., bearing load of the optical fibre preform weight in order to load the optical fibre preform into the drawing furnace for drawing process.
[0043] The length side of the plurality of plates forms a horizontal portion and the breadth side of the plurality of plates forms a vertical portion of the plurality of plates. The length side of the plurality of plates is greater than the breadth side of the plurality of plates. In an example, the height (HI) of the hot changeover apparatus (100) may be 76 mm, the width (Wl) of the hot changeover apparatus (100) may be 205 mm, and the length (LI) of the hot changeover apparatus (100) may be 684 mm. However, based on the requirement and implementation, the length, the width and the height of the hot changeover apparatus (100) may also vary. The shape and size of the hot changeover apparatus (100) does not limit the scope of the present disclosure. Similarly, based on the requirement and implementation, the length, the width and the height of the various elements in the hot changeover apparatus (100) may vary. The shape and size of the various elements in the hot changeover apparatus (100) does not limit the scope of the present disclosure.
[0044] Advantageously, the hot changeover apparatus (100) may reduce waiting time for loading of next preform for the drawing process. The hot changeover apparatus (100) may improve in quantity of manufactured optical fibre since the waiting time is reduced. That is, because the optical fibre preform

is cooled rapidly from 50 minute to 20-25 minute bringing down the temperature from 2000 to 1000 degree Celsius, thus production is improved to 80 km per tower. The hot changeover apparatus (100) may improve furnace working period as cooling of furnace allows the graphite rods (tubes) to work more without oxidising easily. The openable shutter system (130) allows sealing of the optical fibre drawing furnace in less than five seconds after pulling out of the optical fibre preform from the optical fibre drawing furnace. Due to the closing of the plate(s), the graphite rods in the optical fibre drawing furnace does not come into contact with atmospheric air/gases, hence oxidation of the furnace is avoided and life of the optical fibre drawing furnace is improved.
[0045] FIG. 3 illustrates a top sectional view representing the one or more plates (102-106), without the circular step/without the openable shutter system, having the plurality of rings (114). The arrangement and functions of the one or more plates (102-106) having the plurality of rings (114) are already explained in conjunction with FIG. 1 and FIG. 2. In an example, a width (W2) and a length (L2) of the bottom plate (104) may be 206 mm and 300 mm, respectively. Alternatively, the width (W2) and the length (L2) of the bottom plate (104) may vary.
[0046] FIG. 4 and FIG. 5 illustrate front sectional view representing the pneumatic pipe (112) operating the pair of semi-circular jaws in the circular step (132). The arrangement and functions of the pneumatic pipe (112) and the circular step (132) are already explained in conjunction with FIG. 1 and FIG. 2. In an example, an outside diameter the pneumatic pipe (112) may be 6 mm. Alternatively, the outside diameter the pneumatic pipe (112) may vary.
[0047] FIG. 6 and FIG. 7 illustrate front sectional views representing the pneumatic pipe (112) connected with the bottom plate (104) and a spanner (118). The spanner (118) acts as a water connection grip fitting part or a water connection pipe holding part. The spanner may be made of SS316 stainless steel or any other suitable material. The arrangement and functions of the pneumatic pipe (112) is already explained in conjunction with FIG. 1 and FIG. 2.

[0048] FIG. 8 illustrates a sectional view representing a support rod (122). FIG. 9 illustrates a sectional view of the water connector (108a). The support rod (122) controls operation of the pair of semi-circular jaws while the water connector (108a) provides the water connection or flow of water inside the plurality of plates (102-106) for transfer of heat. FIG. 10 and FIG. 11 illustrate a front view and a side view of the one or more plates (102-106) depicting a slot/point for water exit and water entry i.e., the water intake port (108b) and the water exit port (108c) as explained above. FIG. 12 to FIG. 14 illustrate a side view representing one or more side plate supports (128) (FIG. 14) to which a guide cylinder (110) (FIG. 12 and FIG. 13) is connected. The guide cylinder (110) allows opening and closing of the openable shutter/jaws.
[0049] It will be apparent to those skilled in the art that other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention. While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above-de scribed embodiment, method, and examples, but by all embodiments and methods within the scope of the invention. It is intended that the specification and examples be considered as exemplary, with the true scope of the invention being indicated by the claims.
[0050] Conditional language used herein, such as, among others, "can," "may," "might," "may," "e.g.," and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain alternatives include, while other alternatives do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more alternatives or that one or more alternatives necessarily include logic for deciding, with or without other input or prompting, whether

these features, elements and/or steps are included or are to be performed in any particular alternative. The terms "comprising," "including," "having," and the like are synonymous and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. Also, the term "or" is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term "or" means one, some, or all of the elements in the list.
[0051] Disjunctive language such as the phrase "at least one of X, Y, Z," unless specifically stated otherwise, is otherwise understood with the context as used in general to present that an item, term, etc., may be either X, Y, or Z, or any combination thereof (e.g., X, Y, and/or Z). Thus, such disjunctive language is not generally intended to, and should not, imply that certain alternatives require at least one of X, at least one of Y, or at least one of Z to each be present.
[0052] While the detailed description has shown, described, and pointed out novel features as applied to various alternatives, it can be understood that various omissions, substitutions, and changes in the form and details of the devices or algorithms illustrated can be made without departing from the scope of the disclosure. As can be recognized, certain alternatives described herein can be embodied within a form that does not provide all of the features and benefits set forth herein, as some features can be used or practiced separately from others.

CLAIMS
We Claim:

1. A hot changeover apparatus (100) for use in an optical fibre drawing furnace,
comprising:
an openable shutter system (130) arranged near a top portion of the optical fibre drawing furnace, wherein the openable shutter system (130) seals the optical fibre drawing furnace in a closed configuration, wherein the closed configuration is triggered when the optical fibre drawing furnace is in a heated state and a changeover state, wherein the heated state of the optical fibre drawing furnace is defined by a temperature between 1700-2200 degree Celsius, wherein the changeover state of the optical fibre drawing furnace is associated with exit of residual of a previous optical fibre preform after drawing and before insertion of a subsequent optical fibre preform, wherein the openable shutter system (130) enables sealing for the optical fibre drawing furnace when a diameter variation of the optical fibre preform along a preform length is up to 20mm; and
a cooling system (108d) integrated into the openable shutter system (130), wherein the cooling system (108d) comprises one or more coolant channels (108b, 108c), wherein a cooled state is associated with a temperature about 1000 degree Celsius, wherein an insertion state is associated with insertion of the subsequent optical fibre preform and an open configuration of the openable shutter system (130).
2. The hot changeover apparatus (100) as claimed in claim 1, wherein the openable shutter system (130) comprising a top plate (102), a middle plate (106) and a bottom plate (104), wherein the middle plate (106) is sandwiched between the top plate (102) and the bottom plate (104), wherein each of the top plate (102), the middle plate (106) and the bottom plate (104) has a concentric hole section.
3. The hot changeover apparatus (100) as claimed in claim 2, wherein the bottom plate (104) comprises one or more moving jaws to transition the openable shutter system (130) between the open configuration and the closed configuration.

4. The hot changeover apparatus (100) as claimed in claim 2, wherein the middle plate (106) has hollow sections forming one or more coolant channels (108b, 108c).
5. The hot changeover apparatus (100) as claimed in claim 2, wherein the top plate (102) comprises a plurality of rings (114), wherein the plurality of rings (114) aids in assembling of components to hold the optical fibre preform in the optical fibre drawing furnace.

6. The hot changeover apparatus (100) as claimed in claim 1, wherein the openable shutter system (130) allows sealing of the optical fibre drawing furnace in less than five seconds after pulling out of the optical fibre preform from the optical fibre drawing furnace.
7. The hot changeover apparatus (100) as claimed in claim 1, wherein the one or more coolant channels (108b, 108c) bring the optical fibre drawing furnace in the cooled state and in the insertion state in less than 30 mins.
8. The hot changeover apparatus (100) as claimed in claim 1, wherein the hot changeover apparatus (100) comprises a plurality of stacked plates (102-106), wherein each plate has a circular section such that the circular section of each of the plurality of stacked plates is concentric, wherein at least one plate has movable sections to enable the openable shutter system (130) transition among the closed configuration, the open configuration and a sealing configuration, wherein the sealing configuration is associated with sealing of radial gap between the optical fibre preform and the optical fibre drawing furnace.
9. The hot changeover apparatus (100) as claimed in claim 1, wherein the openable shutter system (130) comprises a pair of semi-circular plates, wherein the pair of semi-circular plates has an arc on its diameter side, wherein the arc on

the pair of semi-circular plates forms a circular step (132) in the openable shutter system (130).