Blowtorch apparatus and method of use

Abstract

A gas blowtorch 100 for providing heat around an outer surface of a heat shrinkable object (201, fig 2) comprises a blowtorch head 101 having a conduit which has a plurality of apertures 102 along its length for directing a plurality of flames at the object. A handle 109 connected to the head is for positioning the head relative to the object. The length dimension of the conduit forms an open shape with two end portions and the handle connects to the head at a connection point 103 offset to a line perpendicular to the middle point of a line intersecting the two end portions. The offset may be at an angle between 45 and 135 degrees, and preferably 90 degrees. There may be 8 to 50 and preferably 25 apertures that may be circular or slotted, with slots improving uniformity of heat to be applied to the object. The open shape of the conduit may have a major arc profile with the apertures on the interior concave surface to direct flames inwards. The handle may comprise a torch head connector 104, oxygen control pipe section 10, gas control screw 106, handle connector 108, trigger 110 and adjustment nozzles 111.

Description

The present invention relates to a blowtorch apparatus and a method of use. The invention has particular applications in heating industrial heat shrink tubing, for example in high-voltage power transmission systems. Background to the invention Heat shrink tubing is commonly used in a range of industrial applications, for example to provide electrical insulation and protection for wires, cables and other components. When applying heat shrink tubing to a cable for high-voltage power transmission, common practice is to use a gas blowtorch with a single concentrated flame. In such circumstances, a skilled operator must precisely move the flame around the circumference of the tubing, as well as along its length, to shrink the tubing. This practice can be time consuming and can lead to uneven heating of the tubing, including localised overheating and burning. If the tubing overheats, this may damage either the tubing itself or the underlying cable, and it may then be necessary to disassemble and replace the heat shrink tubing and cable. If this issue occurs, this can be time consuming to rectify, and it can add additional material costs. As such, there is a requirement for techniques which enable the fast and uniform heating of the heat shrink tubing, thereby improving the reliability and speed of such heat shrinking operations. CN102374653A, CN201764704U and CN201944852U describe devices which attempt to solve different issues within various heat shrink tubing applications. In CN102374653A, the device comprises a U-Shaped pipe which is connected to a gas pipe. The U-shaped pipe has eleven holes drilled in it for applying heat to an object which is positioned in the U-shaped opening. CN201764704U describes a C-shaped heat gun. Eight air outlets are provided on the inner side of the heat gun. Hot air blows through the air outlet holes providing heat for the heat shrinking of an object positioned in the C-shaped opening. CN201944852U also describes a C-shaped device. Twelve holes are uniformly distributed on the inner wall of the device. These holes provide the flames necessary for performing heat shrinking of an object positioned in the C-shaped opening. These known methods attempt to solve different issues associated with providing uniform heating for heat shrinking operations. However, when using these devices it is challenging to provide the level of control over the uniformity of applied heat that is important in industrial heat shrinking applications, such as in high-voltage power transmission systems. Summary of the invention It is amongst the aims and objects of the invention to provide an apparatus and a method of use for improving heat distribution in heat shrink tubing applications, which is an alternative to the methods and apparatus described in the prior art, and which addresses one or more of the problems of known apparatus and methods. It is amongst the aims and objects of the invention to provide an apparatus and method of use which improves the ease by which the blow torch apparatus can be used for heat shrink tubing applications, which obviates or mitigates one or more drawbacks or disadvantages of known methods. It is amongst the aims and objects of the invention to provide an apparatus and method of use which can reduce the time required for performing heat shrinking operations, as well as increase the reliability with which these operations can be performed. Further objects and aims of the invention will become apparent from the following description. According to a first aspect of the invention, there is provided a gas blowtorch head for providing heat around an outer surface of a heat shrinkable object, the gas blowtorch head comprising: - a conduit which has a plurality of apertures along its length for directing a plurality of flames at the object; - wherein the plurality of apertures have a slotted shape to improve the uniformity of heat that is applied to the outer surface of the object. When the gas blowtorch head is positioned to provide heat around the outer surface of the heat shrinkable object, the gas blowtorch head may extend substantially around the outer surface of the object. The conduit may follow the shape profile of a major arc. The plurality of apertures may be positioned on an interior concave surface of the gas blowtorch head such that the plurality of flames are directed in an inwards direction towards the outer surface of the object. The major axes of the plurality of apertures may be orientated substantially perpendicular to the plane of the gas blowtorch head. In an alternative embodiment, the major axes of the plurality of apertures may be orientated at an angle which is offset to an angle perpendicular to the plane of the gas blowtorch head. In both of these embodiments, the orientation of the major axes of the plurality of apertures may improve the distribution of heat that is applied to the outer surface of the object. The quantity of the apertures may be in the range of 8 to 50. In a preferred embodiment, the quantity of the apertures may be 25. There may be provided a handle connected to the gas blowtorch head for positioning the gas blowtorch head relative to the object. In its length dimension, the conduit of the gas blowtorch head may form an open shape with two end portions, and the handle may connect to the gas blowtorch head at a connection point that is offset to a line perpendicular to the middle point of a line intersecting the two end portions. The connection point of the handle to the gas blowtorch head may be offset to the line perpendicular to the middle point of the line intersecting the two end sections, by an angle in the range of 45 degrees to 135 degrees. In another embodiment, the connection point may be offset by an angle in the range of 80 to 110 degrees. In a preferred embodiment, the connection point may be offset by an angle of approximately 90 degrees. An excluded portion of conduit may be defined as the portion of conduit not present in a minor arc formed between the two end portions. The centre point of the excluded portion may be offset from the connection point of the handle to the gas blowtorch head by an angle of approximately 90 degrees. The positioning of the excluded portion, relative to the connection point of the handle to the gas blowtorch head, may improve the ease by which an operator can move the gas blowtorch head into a required position for providing heat around the outer surface of the heat shrinkable object. The positioning of the excluded portion may enable the operator to move the gas blowtorch head into the required position in a substantially vertically downwards direction from vertically above the object. In an alternative embodiment, the positioning of the excluded portion may enable the operator to move the gas blowtorch head into the required position in a substantially vertically upwards direction from vertically below the object. The angle of the minor arc of the excluded portion may be greater than 30 degrees and may be less than 180 degrees. In a preferred embodiment, the angle may be between 90 and 120 degrees. The handle may comprise a connection piece, wherein the connection piece connects to the gas blowtorch head at the connection point. The connection piece may be in the form of a conduit which carries a gas to the gas blowtorch head. The conduit formed in the connection piece and the conduit formed in the gas blowtorch head may form a T-Junction at the connection point, wherein the gas flows through the conduit in the connection piece and wherein the gas flow separates into two distinct flow paths when entering the gas blowtorch head. As such, when the gas flow enters the gas blowtorch head, the gas may impact with a conduit wall of the conduit formed in the gas blowtorch head, and this impact may dissipate some of the energy of the gas, allowing for a more uniform distribution of the size of the flames formed across the plurality of apertures. According to a second aspect of the invention, there is provided a method of providing heat around an outer surface of an object for heat shrink tubing applications, the method comprising using the gas blowtorch head of the first aspect of the invention. According to a third aspect of the invention, there is provided a gas blowtorch for providing heat around an outer surface of a heat shrinkable object, the gas blowtorch comprising: a gas blowtorch head which comprises a conduit which has a plurality of apertures along its length for directing a plurality of flames at the object; and - a handle connected to the gas blowtorch head for positioning the gas blowtorch head relative to the object; - wherein in its length dimension the conduit forms an open shape with two end portions; and - wherein the handle connects to the gas blowtorch head at a connection point that is offset to a line perpendicular to the middle point of a line intersecting the two end portions. The connection point of the handle to the gas blowtorch head may be offset to the line perpendicular to the middle point of the line intersecting the two end sections, by an angle in the range of 45 degrees to 135 degrees. In another embodiment, the connection point may be offset by an angle in the range of 80 to 110 degrees. In a preferred embodiment, the connection point may be offset by an angle of approximately 90 degrees. The plurality of apertures may have an approximately circular shape formed in a wall of the conduit. In a preferred embodiment, the plurality of apertures may have a slotted shape. The slotted shape may improve the uniformity of heat that is applied to the outer surface of the object. The major axes of the slotted shape may be orientated substantially perpendicular to the plane of the gas blowtorch head. In an alternative embodiment, the major axes of the slotted shape may be orientated at an angle which is offset to an angle perpendicular to the plane of the gas blowtorch head. The orientation of the major axes of the slotted shape may improve the distribution of heat that is applied to the outer surface of the object. The quantity of the apertures may be in the range of 8 to 50. In a preferred embodiment, the quantity of the apertures may be 25. When the gas blowtorch head is positioned to provide heat around the outer surface of the heat shrinkable object, the gas blowtorch head may extend substantially around the outer surface of the object. The open shape of the conduit may follow the profile of a major arc. The plurality of apertures may be positioned on the interior concave surface of the gas blowtorch head such that the plurality of flames are directed in an inwards direction towards the outer surface of the object. An excluded portion of conduit may be defined as the portion of conduit not present in a minor arc formed between the two end portions. The centre point of the excluded portion may be offset from the connection point of the handle to the gas blowtorch head by an angle of approximately 90 degrees. The positioning of the excluded portion, relative to the connection point of the handle to the gas blowtorch head, may improve the ease by which an operator can move the gas blowtorch head into a required position for providing heat around the outer surface of the heat shrinkable object. The positioning of the excluded portion may enable the operator to move the gas blowtorch head into the required position in a substantially vertically downwards direction from vertically above the object. In an alternative embodiment, the positioning of the excluded portion may enable the operator to move the gas blowtorch head into the required position in a substantially vertically upwards direction from vertically below the object. The angle of the minor arc of the excluded portion may be greater than 30 degrees and may be less than 180 degrees. In a preferred embodiment, the angle may be between 90 and 120 degrees. The handle may comprise a connection piece, wherein the connection piece connects to the gas blowtorch head at the connection point. The connection piece may be in the form of a conduit which carries a gas to the gas blowtorch head. The conduit formed in the connection piece and the conduit formed in the gas blowtorch head may form a T-Junction at the connection point, wherein the gas flows through the conduit in the connection piece and wherein the gas flow separates into two distinct flow paths when entering the gas blowtorch head. As such, when the gas flow enters the gas blowtorch head, the gas may impact with a conduit wall of the conduit formed in the gas blowtorch head, and this impact may dissipate some of the energy of the gas, allowing for a more uniform distribution of the size of the flames formed across the plurality of apertures. Embodiments of the third aspect of the invention may include one or more features of the first aspects of the invention or their embodiments, or vice versa. According to a fourth aspect of the invention, there is provided a method of providing heat around an outer surface of an object for heat shrink tubing applications, the method comprising using the gas blowtorch of the third aspect of the invention. According to a fifth aspect of the invention, there is provided a method of moving a gas blowtorch head into a required position for performing a heat shrinking operation, wherein the method comprises: using a gas blow torch head according to the first or third aspects of the invention; and - moving the gas blowtorch head into the required position in either a substantially vertically upward direction or a substantially vertically downward direction. Brief description of the drawings There will now be described, by way of example only, various embodiments of the invention with reference to the drawings, of which: Figure 1A is an exploded-view of a gas blowtorch apparatus, according to an embodiment of this invention; Figure 1B is a graphical representation of the gas blowtorch apparatus, in an assembled form, according to an embodiment of this invention. Figure 2 is a schematic view of the gas blowtorch apparatus in use, according to an embodiment of this invention; Figure 3A is an exploded view of an oxygen control pipe section and a gas control pipe section of the gas blowtorch apparatus, according to an embodiment of this invention; Figure 3B is a cross-section view of the oxygen control pipe section and the gas control pipe section of the gas blowtorch apparatus, in an assembled form, according to an embodiment of this invention; Figure 4A is a graphical representation of a plurality of apertures in the gas blowtorch apparatus, according to an embodiment of this invention; and Figure 4B is a graphical representation of a plurality of apertures in the gas blowtorch apparatus, according to an alternative embodiment of the invention. Detailed description of preferred embodiments Embodiments of the invention will be described in the context of performing heat shrinking operations for cables used within high-voltage transmission systems. This is by way of example only, and it will be appreciated in at least some of its aspects, that this invention is applicable to shrinking operations in other industries. It will also be appreciated that this invention is applicable in other industries which do not involve heat shrinking operations, but which more generally require the application of distributed heat around the surface of an object. Referring firstly to Figure 1 A, there is shown an exploded-view of a gas blowtorch apparatus 100 for performing heat shrinking operations. The apparatus 100 comprises a gas blowtorch head 101, into which a number of apertures 102 are formed. The blowtorch head 101 is connected via a number of connection pieces to a handle, shown generally at 109. The connection pieces include a torch head connector 104 which is connected to the blowtorch head 101 at a connection point 103, an oxygen control pipe section 105, a gas control pipe section 107 with a gas control screw 106, and a handle connector 108. The handle 109 includes a trigger 110, adjustment nozzles 111, and a gas inlet 112. The handle connector 108, as well as the other connection pieces between the handle 109 and the blowtorch head 101, can come in a variety of lengths depending on the specific application of the apparatus 100. In the embodiment described herein, the inventors have found that when considering the distance between the handle 109 and the connection point 103, a total length of approximately 20 cm is most suitable, but that this total length may vary between approximately 10 cm and 150 cm. All the pipe sections and connection pieces are connected to one another through an appropriate means, including welding where a permanent connection is required, or through threaded or bayonet connections where a readily reversible connection is required. The apparatus 100 is shown in its fully assembled form in Figure 1B, with the same features indicated by the same reference numerals. Gas enters the apparatus 100 through the gas inlet 112. The gas then flows through the handle 109 and through the connection pieces 108, 107, 105 and 104. Following this, the gas enters the blowtorch head 101 at the connection point 103, dispersing through the conduit formed in the blowtorch head 101 and then exiting the apparatus 100 through the apertures 102. The handle 109 includes the adjustments nozzles 111 and the trigger 110, which the operator can use to control the gas flow rate into the blowtorch head 101. Figure 2 graphically illustrates a partially completed heat shrinking operation using the blowtorch apparatus 100. Flames 202, which are formed by the ignition of the gas mixture that is emitted from the apertures 102, provide the heat energy necessary for performing the heat shrinking operation. An object 200 is shown, around which a section of heat shrink tubing 201 is placed. The gas blowtorch apparatus 100 has been moved into the position shown in Figure 2, such that the flames 202 partially surround the heat shrink tubing 201. The flames 202 combine to form a distributed heat ring 203 which extends around a substantial portion of the heat shrink tubing 201. By positioning the gas blowtorch head 101 such that the heat shrink tubing 201 is positioned towards the centre point of this heat ring 203, heating can be distributed around the circumference of the heat shrink tubing 201. In the partially completed heat shrinking operation shown in Figure 2, the heat shrink tubing 201 has been partially heated, and this is represented by the reduced diameter portion of the tubing 201. By using apparatus 100, heat shrinking can be performed by guiding the blowtorch head 101 along the length of the heat shrink tubing 201 only, and rotation of the blowtorch head 101 circumferentially around the heat shrink tubing 201 is not required. If heating of the heat shrink tubing 201 is required where the heating is distributed non-uniformly around the circumference of the tubing 201, then this can be achieved by positioning the heat shrink tubing 201 and object 200 at a position which is offset from the centre point of the heat ring 203. By performing a heat shrinking operation in this way, the portion of heat shrink tubing 201 closest to the flames 202 will receive more heat energy than the opposing side of the heat shrink tubing 201. The common practice for heat shrinking operations across different industries is to use a single heat source, for example a blowtorch with a single flame. When using a single concentrated flame, in order to provide heating around the full circumference and length of an object, the flame must be moved precisely around the object by a skilled and attentive operator. When providing heat in this manner, it is easy to provide uneven heating of the heat shrink tubing, including localised overheating and burning of the tubing. Therefore, by using an apparatus which provides distributed heating around the circumference of an object, there will be an improvement in the reliability of a heat shrink operation, as well as substantial savings in time. Other advantages of using an apparatus which provides distributed circumferential heating, in comparison to an apparatus with a single flame, include that the heat shrink tubing 201 will shrink more uniformly around the circumference of the object 200 and will therefore better conform to the underlying object 200. Furthermore, the operator does not need to move around the heat shrink tubing to the extent that would be required when using a blowtorch with a single flame. When heat shrinking in high-voltage power transmission systems, this is beneficial as the operator will not need to bend under or around cables, and these are actions which present potential operational safety hazards. Figure 3A illustrates an exploded-view of the oxygen control pipe section 105, the gas control pipe section 107 and the gas control screw 106, which together are used to control the gas-to-air ratio that flows into the blowtorch head 101. Air inlet holes 301 are shown in the oxygen control pipe 105. Figure 3B illustrates a schematic cross-sectional view of the assembled oxygen control pipe section 105, gas control pipe section 107 and gas control screw 106. Gas flows into the gas control pipe section 107 in the direction A. This gas then flows through the jet nozzle hole 302 in the centre of the gas control screw 106 and enters the oxygen control pipe section 105. Air enters the air inlet holes 301 and mixes with the gas. The gas-air mixture then flows through the torch head connector 104 and enters then enters the blowtorch head 101. In order to control the gas-to-air ratio that enters the blowtorch head 101, a number of parameters must be carefully controlled relative to one another. These include the diameter of the jet nozzle hole 302, the number and size of the air inlet holes 301, as well as the flow rate of gas into the gas control pipe section 107, which can be controlled through the adjustment nozzles 111 and trigger 110 on the handle 109. In the embodiment described herein, the inventors have identified that the diameter of the jet nozzle hole 302 may vary between approximately 0.8 mm and 1.2 mm, and that a value of approximately 1.1 mm is most suitable. In addition, the inventors have identified that having four air inlet holes 301, each with a cross-sectional area approximately equal to the cross-sectional area of the conduit formed in the gas control pipe section 107, is most suitable. Figure 4A graphically illustrates the apertures 102 formed in the blowtorch head 101, according to an embodiment of this invention. The apertures 102 are illustrated as being slot-shaped with their major axes at a perpendicular angle to the plane of the blowtorch head 101. The inventors have identified that the shape of the apertures affects the distribution of heat that is applied to the heat shrink tubing 201. In particular, the inventors have identified that a slot-shaped aperture is preferable over the circular-shaped apertures that are commonly found in blowtorches used for industrial heat shrink tubing. A standard circular-shaped aperture was found to result in a more focused flame, where the heat energy is more concentrated. In contrast to this, a slot-shaped aperture was identified to result in a wider shaped flame with heat distributed over a wider area. In particular, in the embodiment shown, heat energy will be more widely distributed in the axial direction of the heat shrink tubing 201. Figure 4B graphically illustrates the apertures 102 formed in the blowtorch head 101, according to an alternative embodiment of this invention. Similarly to Figure 4A, slotshaped apertures 102 in the blowtorch head 101 are shown. However, in Figure 4B, the apertures 102 are shown orientated at an inclined angle to the plane of the blowtorch head 101. The inventors found that angling the apertures 102 in this way can be beneficial in heat shrink tubing applications as it can improve the distribution of the heat energy of the flames 202 in the circumferential direction of the heat shrink tubing 201. In the particular embodiment shown, the apertures 102 have an angle in the range of approximately 30 degrees to 60 degrees. In the embodiment illustrated in Figure 1 and Figure 2, the blowtorch head 101 is in the form of a conduit which follows the profile of a major arc, with an excluded portion defined between the two end portions of the conduit. The excluded portion is positioned circumferentially in the blowtorch head 101 to facilitate the ease by which the blowtorch head 101 can be moved into a required position for performing the heat shrinking operation. As shown in Figure 2, the excluded portion is positioned across the uppermost vertical point of the blowtorch head 101, when the apparatus 100 is held horizontally by the operator. Therefore, the blowtorch head 101 can be moved into the required position in a vertically upwards direction from below the object 200. Alternatively, the apparatus 100 can be used where the excluded portion is positioned across the lowermost vertical point of the blowtorch head 101 instead. In this circumstance, the blowtorch head 101 can instead be moved into the required position by moving the blowtorch head 101 in a vertically downwards direction from above the object 200. The inventors have found that these two vertical directions of movement are the most effective ways by which the blowtorch head 101 can be moved into position for performing heat shrinking operations. A large portion of the total weight of the apparatus 100 is attributed to the weight of the blowtorch head 101, and the apparatus 100 therefore has a centre of mass at a large distance from the handle 109. As such, the inventors have found that moving the blowtorch head 101 into position around the heat shrink tubing 201 requires the least physical effort for the operator when moving in a substantially vertical direction. In view of this, moving the blowtorch head 101 in this vertical direction also gives the operator the best control over the positioning of the blowtorch head 101 relative to the heat shrink tubing 201. To enable these vertical directions of movement, the connection point 103 must be located at a position which is offset from the line of symmetry of the major arc formed by the shape of the blowtorch head 101. By having the connection point 103 at this offset position, this presents difficulties with maintaining a sufficiently uniform flow through the apertures 102. The angle of arc of the two portions of the blowtorch head 101 defined between the connection point 103 and the two end portions of the blowtorch head 101 are significantly different in the embodiment shown. As such, the gas-air mixture must be appropriately distributed between these two portions of the blowtorch head 101. The above issues have been addressed in the design of apparatus 100. There are a number of design parameters which the inventors identified as being important in addressing these issues. These include, the flow rate of the gas-air mixture entering the blowtorch head 101 at the connection point 103, the diameter of the major arc formed by the shape of the blowtorch head 101, as well as the diameter of the conduit through which the gas-air mixture flows within the blowtorch head 101. In the embodiment described herein, the inventors have identified that the diameter of the conduit of the blowtorch head 101 may vary between approximately 10 mm and 26 mm, and that a value of approximately 16 mm is most suitable. The inventors have also identified that the diameter of the major arc formed by the blowtorch head 101 may typically vary between approximately 8 cm and 36 cm. However, it is also recognised that different diameters may be applicable in different embodiments. In particular, the diameter of the major arc formed by the blowtorch head 101 will be closely linked to the diameter of the heat shrink tubing 201. As an example, if a heat shrinking operation is being performed on a section of heat shrink tubing 201 with a particularly small diameter, then the diameter of the major arc of the blowtorch head 101 will also need to be reduced to ensure that the heat shrink tubing 201 receives sufficient heat energy from the flames 202. Furthermore, if the heat shrink tubing 201 has a particularly large diameter in relation to the diameter of the major arc of the blowtorch head 101, then the heat shrink tubing 201 may receive too much heat energy from the flames 202. Accordingly, the diameter of the major arc of the blowtorch head 101 may be scaled up or down depending on the dimensions of the heat shrink tubing 201. In addition, the inventors identified that the angle of arc of the blowtorch head 101 and the excluded portion, the positioning of the connection point 103 relative to the blowtorch head 101, as well as the size, shape, position and number of the apertures 102, are all parameters that must be carefully controlled. In the embodiment described herein, the inventors identified that the total quantity of apertures 102 may vary between approximately 8 and 50, and that a quantity of approximately 25 is most suitable. When selecting the quantity and size of the apertures 102, it was identified that if these were too small in quantity and size, then the gas-air mixture would be ejected through the apertures 102 with such force that the flames 202 on the opposing side of the blowtorch head 101 would be extinguished. Alternatively, it was found that the gas-air mixture may instead be forced out of and ignite through the air inlet holes 301 instead of the apertures 102. In contrast, if the quantity or size of the apertures 102 was too large, then the size of the flames 202 may become too small and consequently not provide enough heat energy for the heat shrinking operation. The apparatus 100 is designed such that at the connection point 103, where the gas flow through the torch head connector 104 enters the conduit in the blowtorch head 101, a T-junction is formed. As the gas-air mixture enters the blowtorch head 101 it therefore impacts the inner wall of the conduit formed in the blowtorch head 101. The inventors have found that this impact on the inner wall is beneficial as it dissipates some of the energy of the gas-air mixture, allowing flow of the gas-air mixture to be more uniform across the plurality of apertures 102 in the blowtorch head 101. In contrast, if the blowtorch head 101 and the torch head connector 104 are formed from a single continuous section of bent pipe, without the presence of a T-junction, the inventors found that the flow of the gas-air mixture across the plurality of apertures 102 in the blowtorch head 101 had reduced uniformity. In particular, the inventors found that there was a low flowrate of the gas-air mixture through the apertures 102 closest to the connection point 103, and a relatively higher flowrate through the apertures 102 positioned furthest away from the connection point 103. The invention provides a gas blowtorch for providing heat around an outer surface of a heat shrinkable object, and a method of use of the gas blowtorch. The gas blowtorch comprises a gas blowtorch head, and the gas blowtorch head further comprises a conduit which has a plurality of apertures along its length for directing a plurality of flames at the object. A handle is connected to the gas blowtorch head for positioning the gas blowtorch head relative to the object. In its length dimension the conduit forms an open shape with two end portions. The handle connects to the gas blowtorch head at a connection point that is offset to a line perpendicular to the middle point of a line intersecting the two end portions. Various modifications to the above-described embodiments may be made within the scope of the invention, and the invention extends to combinations of features other than those expressly claimed herein.

Claims

1. A gas blowtorch for providing heat around an outer surface of a heat shrinkable object, the gas blowtorch comprising:a gas blowtorch head which comprises a conduit which has a plurality of apertures along its length for directing a plurality of flames at the object; anda handle connected to the gas blowtorch head for positioning the gas blowtorch head relative to the object;wherein in its length dimension the conduit forms an open shape with two end portions; andwherein the handle connects to the gas blowtorch head at a connection point that is offset to a line perpendicular to the middle point of a line intersecting the two end portions.

2. The gas blowtorch according to claim 1, wherein the connection point of the handle to the gas blowtorch head is offset to the line perpendicular to the middle point of the line intersecting the two end sections, by an angle in the range of 45 degrees to 135 degrees.

3. The gas blowtorch according to claim 2, wherein the connection point is offset by an angle of approximately 90 degrees.

4. The gas blowtorch according to any preceding claim, wherein the plurality of apertures have an approximately circular shape formed in a wall of the conduit.

5. The gas blowtorch according to any preceding claim, wherein the plurality of apertures have a slotted shape, and wherein the slotted shape improves the uniformity of heat that is applied to the outer surface of the object.

6. The gas blowtorch according to claim 5, wherein the major axes of the slotted shape is orientated substantially perpendicular to the plane of the gas blowtorch head.

7. The gas blowtorch according to claim 6, wherein the major axes of the slotted shape is orientated at an angle which is offset to an angle perpendicular to the plane of the gas blowtorch head.

8. The gas blowtorch head according to any preceding claim, wherein the quantity of the apertures is in the range of 8 to 50.

9. The gas blowtorch head according to claim 8, wherein the quantity of the apertures is 25.

10. The gas blowtorch head according to any preceding claim, wherein when the gas blowtorch head is positioned to provide heat around the outer surface of the heat shrinkable object, the conduit of the gas blowtorch head extends substantially around the outer surface of the object.

11. The gas blowtorch head according to any preceding claim, wherein the open shape of the conduit follows the profile of a major arc.

12. The gas blowtorch head according to any preceding claim, wherein the plurality of apertures are positioned on the interior concave surface of the gas blowtorch head such that the plurality of flames are directed in an inwards direction towards the outer surface of the object.

13. The gas blowtorch head according to any preceding claim, wherein an excluded portion of conduit is defined as the portion of conduit not present in a minor arc formed between the two end portions, and wherein the centre point of the excluded portion is offset from the connection point of the handle to the gas blowtorch head by an angle of approximately 90 degrees.

14. The gas blowtorch head according to claim 13, wherein the positioning of the excluded portion, relative to the connection point of the handle to the gas blowtorch head, improves the ease by which an operator can move the gas blowtorch head into a required position for providing heat around the outer surface of the heat shrinkable object.

15. The gas blowtorch head according to claim 14, wherein the positioning of the excluded portion enables the operator to move the gas blowtorch head into the required position in a substantially vertically downwards direction from vertically above the object and / or enables the operator to move the gas blowtorch head intothe required position in a substantially vertically upwards direction from vertically below the object.

16. The gas blowtorch head according to any of claims 13 to 15, wherein the angle of the minor arc of the excluded portion is greater than 30 degrees and less than 180 degrees.

17. The gas blowtorch head according to claim 16, wherein the angle is between 90 and 120 degrees.

18. The gas blowtorch head according to any preceding claim, wherein the handle further comprises:a connection piece;wherein the connection piece connects to the gas blowtorch head at the connection point;wherein the connection piece is in the form of a conduit which carries a gas to the gas blowtorch head;wherein the conduit formed in the connection piece and the conduit formed in the gas blowtorch head form a T-Junction at the connection point;wherein the gas flows through the conduit in the connection piece and separates into two distinct flow paths when entering the gas blowtorch head; andwherein, when the gas flow enters the gas blowtorch head, the gas impacts with a conduit wall of the conduit formed in the gas blowtorch head, and this impact dissipates some of the energy of the gas, allowing for a more uniform distribution of the size of the flames formed across the plurality of apertures.

19. A method of providing heat around an outer surface of an object for heat shrink tubing applications, the method comprising using the gas blowtorch according to any preceding claim.

20. A method of moving a gas blowtorch head into a required position for performing a heat shrinking operation, wherein the method comprises:using the gas blow torch head according to any of claims 1 to 18; andmoving the gas blowtorch head into the required position in either a substantially vertically upward direction or a substantially vertically downward direction.18

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