GB2508823A

GB2508823A - Gas venting conduit having an outlet at a pre-determinable height and an associated stand

Info

Publication number: GB2508823A
Application number: GB1222247.7A
Authority: GB
Inventors: Roy Hookway; Robin Matthews; Mark Bartlett
Original assignee: EXPRESS PIPE LAYING AND REPAIRS Ltd
Current assignee: EXPRESS PIPE LAYING AND REPAIRS Ltd
Priority date: 2012-12-11
Filing date: 2012-12-11
Publication date: 2014-06-18
Anticipated expiration: 2032-12-11
Also published as: GB2508823A8; GB201222247D0; GB2508823B

Abstract

A gas main and service vent 1 for venting gas from a gas main or service pipe has a conduit 3 with a gas inlet 7 for receiving gas from the gas main or service pipe and a gas outlet 9 for venting gas from the gas main or service pipe into the atmosphere. The conduit is positionable in a venting configuration in which the gas outlet is at a pre-determined height. A stand, which may comprise a plurality of collapsible legs 5, is integral or releaseably attachable to the conduit and supports the conduit in the venting configuration. The gas outlet 9 is preferably at least 2m above the vent 1.

Description

GAS MAIN VENT

This invention relates to a gas vent, a method for venting gas and associated kits. In particular, this invention relates to the purging of gas from a gas main or service pipe.

Background to the Invention

Natural gas is used both domestically and commercially as a fuel and must be handled carefully because it readily ignites and can be explosive, when mixed with air.

A gas main is the major component of a gas distribution network that conveys natural gas from a supply to a source. Gas mains usually run underground and typically have a diameter of 63 millimetres to 400 millimetres. They are frequently manufactured from plastics (such as polyethylene), steel or iron.

Gas mains convey gas to smaller-diameter service pipes, allowing the service pipes to convey natural gas into homes, commercial or industrial buildings, from a gas main.

Working with gas mains, that are able to convey large volumes of natural gas, can be very dangerous. For example, commissioning a gas main involves purging air from the main and decommissioning a gas main involves purging natural gas from the main. The purged gas can contain a mixture of natural gas and air and so it is extremely important that purging occurs in a controlled environment and under closely monitored conditions. For these reasons, specialist equipment is employed to ensure that the gas is handled in the safest possible way.

Typically, a gas main to be commissioned or decommissioned will have a purge point at its end. These points can provide above-ground outlets or terminals at which gas from the pipe can be sampled, monitored and/or purged. Conventionally, when purging, a steel tube or stack is connected directly to the main with screw or compression fittings. The stack extends vertically from the purge point ensuring that the venting of mains gas into the atmosphere occurs at a safe height (typically about 2.5 metres above ground level to meet regulatory approval), away from sources of potential ignition.

Often, sections of piping are joined together to create a stack in excess of 5 metres. This is required if a purge point is below ground level, but the vent must extend at least 2.5 metres above the ground level.

When a conventional stack is attached to a gas main it is unstable and prone to wobbling. This instability is a major health and safety hazard. In addition, the instability may be to such an extent that an engineer is required to hold the stack during purging in order to stabilise the stack. This is particularly disadvantageous because the engineer may be required to carry out other tasks during purging, such as monitoring the gas composition. Alternatively, the stack may be supported by a makeshift support by attaching pieces of wood and metal together with string/wire around the vent pipe and across excavations.

Furthermore, attaching the stack directly to a main means that the venting of gas can only occur directly above the gas main, which may not be conveniently located.

It is desirable to improve the safety and convenience of purging mains gas lines during commissioning and decommissioning.

Summary of the invention

This invention provides a gas and service vent, a method for venting gas from a gas main and a kit, as defined in the appended independent claims to which reference should now be made. Advantageous or preferred features are set forth in dependent claims.

Accordingly, the invention may thus provide a gas vent, stack or standpipe, for venting gas from a gas network distribution pipe (such as a gas main or service pipe), comprising: a conduit, pipe or tube having a gas inlet for receiving gas from the gas distribution pipe and a gas outlet for venting gas from the gas distribution pipe into the atmosphere. The conduit may be positionable in a venting configuration in which the gas outlet is at a pre-determined height.

Preferably, the vent is a gas main vent for purging gas from a gas main.

However the vent may be configured or suitable for venting gas from any underground gas pipe, such as service pipes.

Preferably, in the venting configuration, the gas outlet is at a height of at least 2 metres, most preferably at least 2.5 metres from the ground or surface on which the vent is standing, or from the base of the vent in use. The gas outlet may be configured or may be configurable such that, in the venting configuration, the gas outlet is at a height greater than 2.5 metres from the base of the vent. This may be desirable if, for example, the gas main or gas main terminal is underground and the ground must be excavated to access the gas main. The vent may stand, or be supported on a level below ground-level, but the gas outlet may still be at a pre-determined height above the ground level, such as 2.5 metres. For example, if the vent is supported on a level that is 2 metres below ground level, the gas outlet may be at a height of about 4.5 to 5 metres from the base of the vent! in the venting configuration. Preferably, in the venting configuration, the gas outlet is at a height less than or equal to 5, 4 or 3 metres from the base of the vent.

Preferably, in the venting configuration, the gas outlet is at a higher position than the gas inlet. The gas inlet may thus be accessible for connection to a gas source, and not out of reach. The gas inlet may be, for example, at a height from 0 and 1.5 metres from the base of the vent, in the venting configuration.

Advantageously, the vent may also comprise a stand, prop or support for resting or standing on top of a surface and for supporting or maintaining the conduit in the venting configuration.

The vent is preferably free-standing upon a surface (for example, a substantially horizontal surface), such as the ground, or ground-level, above a gas main. The vent may thus be self-supporting. Preferably, the vent does not require direct attachment to a gas main terminal or anything else, such as a wall, to support the vent in the venting configuration.

The stand may advantageously ground or earth the vent to reduce the potential for generating a spark during gas purging.

Preferably, the stand is integral, or is attached or connected to the conduit. The stand may be releasably attachable to, or detachable from the conduit. For example, the vent may be configurable between an attached or connected state, in which the stand is attached or connected to the conduit; and a detached or disconnected state, in which the stand is detached or disconnected from the conduit. In the attached state, the conduit may be supported by the stand and in the detached state, the conduit may not be supported by the stand. If the stand comprises, for example, legs, the legs may be transported separately from the conduit and assembled on site when required. The stand may be collapsible.

The conduit may comprise an attachment or engagement means, such as a housing! with which the stand, or at least a part of the stand, can engage.

Thus, the conduit may be specifically adapted for engaging the stand or a part of the stand. The engagement means, when engaged with the stand, may maintain the stand in a pre-determined configuration or orientation with respect to the conduit.

Thus, if the stand is detachable, assembly of the vent may involve engagement of the stand or part of the stand e.g. a leg with a corresponding housing (or any other engagement means) of the conduit.

In a particularly preferred example, the stand comprises a leg or strut, preferably a plurality of legs, most preferably at least three legs. The leg or legs may be attached to the conduit. The leg or legs may be releasably attachable or releasably engageable with the conduit. The leg or legs may radiate or protrude outwardly from the conduit (or be configurable to radiate or protrude outwardly) to create a base or frame for maintaining and stabilising the conduit in the venting configuration. If there are three legs, the legs may form a tripod.

The leg or legs may be hingedly or rotatably attached to the conduit. In a preferred example, the leg or legs are configurable between a first, folded (or collapsed) state and a second, supporting (or extended) state. The first state may be characterised by the leg or legs being substantially parallel to the longitudinal axis of the conduit (or about 0° with respect to the longitudinal axis of the conduit). The second state may be characterised by the leg or legs radiating from the conduit. Configuration of the second state from the first state may thus comprise rotating the legs from a position where they extend upwardly (or towards the gas outlet), to a position where they extend downwardly or substantially away from the gas outlet. In the second state, the legs preferably radiate at an angle greater than 90° relative to the folded position of the legs in the first state, preferably at an angle between 90° and 1800, most preferably between 120° and 150°.

Advantageously, the vent in the first state may be narrower and may be shorter than in the vent in the second state and may thus be more amenable for transportation and storage. In the second state, the legs may radiate to provide a wide and stable base and may thus support the conduit in the venting configuration, preventing it from wobbling excessively or toppling over.

The leg or legs are preferably lockable or maintainable in the first state and/or the second state. In the first state, this may prevent the legs from swinging or rotating outwardly during transportation and potentially causing injury. In the second state, this may ensure that the stand does not collapse, in use.

The vent may comprise a tie. When the vent is in the first configuration, the tie may fasten around the legs to help maintain the legs in the first configuration and prevent them from splaying outwardly. The tie may be attached to a leg.

The vent may comprise one or more projections, hooks or lugs positioned on each leg. Each projection may be releasably engageable with a corresponding notch or gap on the conduit. For example, the notch may be defined at an edge of the conduit at the gas outlet.

In order to lock or maintain the legs in the second state, the conduit may comprise a housing or housings (for example, one for each leg), into which an end of the leg or legs can be secured. For example, the legs may be slidable into the housings, the housings providing a secure fit for the ends of the legs.

To achieve this, the hinge attaching each leg to the conduit may be a slidable hinge, for example the hinge may comprise a pin that is slidable in a slot.

Preferably, the stand provides a supporting base with an effective diameter, span or width of at least 1.5 metres or at least 2 metres. For example, if the vent comprises three legs, the distance between the bottoms or bases of each leg when the legs are in a supporting configuration is preferably at least 1.5 metres or 2 metres. However, the effective diameter of the base could be adjustable. The width of the base may depend on the height of the vent. For example, a higher vent may require a wider base for greater stability.

Preferably, the leg or legs have a length of at least 1 metre, 1.5 metres or 2 metres.

Preferably the length of the conduit is at least 1.5 metres or at least 2 metres.

Preferably, in the venting configuration, the leg or legs radiate from the conduit at a height of at least 1 metre or greater than 1.5 metres from the base or bottom of the vent.

In the venting configuration, the stand may allow the gas inlet of the conduit to be suspended above the ground, for convenient attachment to a hose (see below).

Although it is preferable for the vent to comprise a stand, this may not be absolutely necessary. For example, the vent could be supported by the user during gas venting, at a position away from the gas main terminal.

To enable the vent to be positioned away, or spaced from, a purge point or a terminal (such as a gas main terminal or service pipe terminal), it is preferable to use a hose or flexible pipe, such as a polyethylene pipe. The gas inlet of the vent may be attached! or may be releasably attachable, to a first end ot the hose. The other end (or second end) of the hose may be adapted for attaching to the terminal. For example, the first end of the hose may be internally or externally threaded. Similarly, the second end of the hose may be internally or externally threaded. The vent may comprise the hose or be in combination with a hose. Advantageously, the hose may permit the positioning of the vent at a convenient location surrounding the terminal, without requiring the vent to be directly attached to the terminal. For example, the vent may be positionable a few metres away from the terminal.

In one embodiment, the gas inlet of the conduit may be incompatible with a purge point or terminal, such that it cannot directly engage the terminal. For example, the gas inlet may comprise a threaded internal or external surface that is not compatible with a threaded internal or external surface of the terminal, such that the threaded surfaces cannot engage. Consequently, it may be that the gas inlet is only compatible or connectable with the terminal using an adaptor, such as a hose, as described above.

The vent is preferably portable, such that it can be carried or conveyed by hand.

In the venting configuration, the conduit is preferably upright or substantially vertical. The conduit is preferably substantially straight. Preferably, the conduit is rigid.

In a particularly preferred example, the conduit comprises a valve configurable between an open state, permitting flow of gas through the conduit from the gas inlet to the gas outlet, and a closed state, preventing or restricting flow of gas through the conduit from the gas inlet to the gas outlet.

The gas inlet may be at a first, lower end of the conduit. The gas outlet may be at a second, higher end of the conduit. For example, the gas inlet and gas outlet may be at opposing ends of the conduit. The gas inlet and/or gas outlet may be arranged such that they are substantially parallel to the longitudinal axis of the conduit.

In a preferred example, the conduit has an internal diameter of at least 20, 30, or 50 millimetres. Preferably, the internal diameter of the conduit is no greater than 100, 150 or 200 millimetres. For example, the internal diameter may be 20 to 200 millimetres.

In a preferred example, the conduit comprises a further (or second) gas outlet, or testing point. Preferably, this is positioned between the (first) gas outlet and the gas inlet. This may provide a means for passage of gas out of the conduit for testing by an engineer. Preferably, when the vent is in the venting configuration, the testing point is at a convenient height for connecting monitoring equipment! such as from about 0.5 metres to 1.5 meters from the base of the vent. An engineer may wish to test that mains gas is connected to the vent or may wish to monitor properties of the gas, such as its composition or pressure. This may prevent the need for having to monitor the composition of the gas exiting the vent at the gas outlet, which may be occurring at an inconvenient height above the ground.

Most preferably, the testing point is positioned between the first gas outlet and the valve. This may allow monitoring of the gas without permitting ejection of gas into the atmosphere from the gas outlet. The testing point may comprise a valve for permitting or preventing/restricting gas flow.

Preferably, the vent is manufactured from a metal such as steel, preferably mild steel or galvanised steel.

The invention may provide a kit comprising a gas vent as described in any form above. The kit may further comprise a hose, having one end for connecting (or specifically adapted to connect) to the gas inlet of the vent, and which may also have a second end for connecting to, or specifically adapted to connect to, a purge point or terminal. The kit may also comprise a device for monitoring gas output from the vent, which may be connectable to the testing point.

The invention may provide a kit comprising a conduit having a gas inlet and a gas outlet. The conduit may comprise one or more engagement means for engaging a stand, or at least part of a stand. For example, the conduit may comprise a housing. The housing may be for receiving an end of a leg or strut.

The end of the leg or strut may be releasably engageable with the engagement means. The kit may also comprise a stand for engaging the engagement means of the conduit. The stand may comprise a leg or legs.

The invention may provide a method for purging or venting gas from a gas pipe, such as a gas main or gas service pipe. The method may comprise obtaining a vent, as defined in any form above; configuring the venting configuration of the vent; attaching the vent to a gas pipe terminal (or purge point); and permitting gas flow from the gas pipe terminal to the vent.

Attaching the vent to the gas terminal may comprise attaching a first end of a pipe, such as a flexible hose to the gas inlet of the vent and attaching a second end of the pipe to the gas pipe terminal. Attachment may occur before or after the configuration of the venting configuration.

Alternatively, the invention may provide a method for purging gas from a pipe (such as a gas a gas main or service pipe), comprising: positioning a gas vent away from a gas pipe terminal, the vent comprising a conduit having a gas inlet for receiving gas from a gas pipe and a gas outlet for venting gas from the gas pipe into the atmosphere; configuring a venting configuration, in which the gas outlet is at a pre-determined height; and connecting a first end of a hose to the gas pipe terminal and connecting a second end of the hose to the gas inlet of the vent.

The method may further comprise configuring a stand such that the stand supports the conduit in the venting configuration.

Description of specific embodiments

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 shows a three-dimensional view of a gas-purging vent according to an embodiment of the invention, the vent being in a venting configuration.

Figure 2 shows a three-dimensional view of a part of the vent of Figure 1.

Figure 3 is a schematic diagram showing a gas-purging vent according to an embodiment of the invention and its connection to a gas-mains terminal.

A vent stack or purge vent 1 as shown in Figures 1 and 2 is manufactured from galvanised steel and has a conduit in the form of a cylinder or tube 3. The tube has a gas inlet 7 at a first, lower end, a gas outlet 9 at a second, upper end and a valve 13 positioned between the gas inlet and the gas outlet, but closer to the lower end of the tube. The tube also has a testing point or outlet 11 in the form of a pressure/GIA sampling point positioned between the gas inlet and the valve. The testing point has a testing valve 15.

The gas inlet 7 has a threaded external surface. In figures 1 and 2, the inlet is engaged with a correspondingly-threaded internal surface of a cap 23.

The gas outlet 9 defines three notches or gaps 31, evenly spaced around its circumference.

Three legs 5 are attached to the outer surface of the tube 3 and are evenly spaced around the outside of the tube. A first end 25 of each leg is hingedly attached to the tube by a bolt 17 and also fits inside a corresponding housing 19. Each bolt is positioned through the housing and engages with a slot (not shown) in the first end of each leg. Each leg has a second end 27, at the opposite end of the leg from the first end. One of the legs has a tie 21 attached to it; made of a hook-and-loop fastening material e.g. Velcro® (although any suitable fastening means could be used). Each leg has a small protrusion or hook 29 on its outside surface, a short distance from its second end.

Figure 1 shows the vent stack 1 in a venting configuration. The tube 3 is upright and the gas inlet? is at a lower position than the gas outlet 9. The gas outlet is at a height of about 2.5 metres from the floor or surface on which the vent is standing. The legs 5 radiate outwardly and downwardly from the conduit such that the second end 27 of each leg rests on the ground, thus providing a stable support or base to maintain the tube in the upright configuration and prevent any excessive movement, such as wobbling. Each housing 19 secures the first end 25 of each leg to maintain their radiated orientation with respect to the tube.

In use, the vent stack 1 is placed in the vicinity of a gas main terminal or service point (not shown) and is set-up in the venting configuration as shown in Figure 1, and as described above. The cap 23 is unscrewed from the gas inlet 7 and a first end of a flexible gas hose (not shown) is connected to the gas inlet. A second end of the hose is connected to the gas main terminal. The tube valve 13 is in a closed configuration, such that if gas is permitted to flow from the terminal to the vent (by, for example, opening a valve at the gas terminal), the gas will not automatically vent from the gas outlet 9.

A device such as a pressure gauge/gas sensor can be connected to the testing point 11, to sample and monitor the properties of the gas. Opening the testing point valve 15 permits gas flow into the connected device. The testing point valve can permit gas flow into the device without requiring opening of the tube valve 13. It may be advantageous to monitor properties of the gas before venting it into the atmosphere.

Opening the tube valve 13 permits venting gas from the gas outlet 9 of the tube 3. Once the tube valve is open, gas will flow from the terminal, through the hose, into the gas inlet 7, up the tube and out of the gas outlet. Gas is emitted into the atmosphere at a safe height.

During purging, the user may wish to continually monitor the properties of the gas and so may open and close the testing point valve 15, as desired.

Once purging is completed, the tube valve 13 is closed (in addition to the valve at the gas mains terminal) and the hose is disconnected from the gas inlet 7.

The vent stack 1 can then be configured to a folded state, for transportation.

To configure the folded state, the first end 25 of each leg 5 is pulled away from or slid out of its respective housing 19, such that each leg can rotate about its respective bolt 17. Each leg is rotated upwardly (such that the second end 27 of each leg rotates towards the gas outlet 9) until each leg reaches a position in which it is substantially parallel to the tube 3. The projections 29 on the legs engage the notches 31 defined at the gas outlet 9 by hooking over the notches.

This prevents rotation of the legs away from the tube. Unhooking the projections permits rotation of the legs away from the tube and configuration of the venting configuration.

When in the folded configuration, wrapping the tie 21 around the three legs and fastening the tie helps to maintain the legs in the folded configuration. In the folded configuration, the vent stack is more compact and so it can be transported more easily.

A vent stack 1 according to another embodiment of the invention is shown schematically in Figure 3. Similar features have been given like reference numerals. Figure 3 shows the arrangement of the vent in relation to a gas main terminal, purge point, or meter box adaptor 33 and the connection of the vent to the gas main terminal by a flexible hose 35. The gas main terminal forms part of a test point 39, which branches from an underground gas main 37, the gas main terminal being accessible at ground level.

A first end 36a of the hose 35 is attached to the gas inlet 7 of the vent by screwing the first end of the hose to the gas inlet. A second end 36b of the hose is attached to the gas main 37, by attaching to the gas main terminal 33.

The hose has a valve 41 situated at its second end.

The vent 1 is positioned in a venting configuration on top of the ground 43 and is spaced from the gas main terminal 33. Flow of gas from the gas main, through the hose 35 is permitted by configuring the hose valve 41 into an open configuration. Venting of gas from the vent may occur as described above in relation to the embodiment shown in figures 1 and 2.

Claims

Claims 1. A gas main and service vent for venting gas from a gas main or service pipe, comprising: a conduit having a gas inlet for receiving gas from the gas main or service pipe and a gas outlet for venting gas from the gas main or service pipe into the atmosphere, the conduit being positionable in a venting configuration in which the gas outlet is at a pre-determined height; and an integral stand for supporting the conduit in the venting configuration, or in which the conduit is specifically adapted to engage or attach to a stand for supporting the conduit in the venting configuration.
2. A vent according to claim 1 in which the stand is collapsible.
3. A vent according to claim 1 or claim 2, in which the stand comprises a plurality of legs, preferably three legs.
4. A vent according to claim 2 or claim 3, in which the legs are hingedly attached to the conduit.
5. A vent according to claims 3 or claim 4, in which the legs are configurable between a first state and a second state, the first state characterised by the legs being substantially parallel to a longitudinal axis of the conduit, and the second state being characterised by the legs radiating from the conduit.
6. A vent according to claim 5, in which the legs are lockable or retainable in the second state.
7. A vent according to claim 5 or 6, in which the conduit comprises a plurality of housings into which an end of each leg can be secured.
8. A vent according to any of claims 3 to 7, in which each leg has a length of at least 1 metre, preferably at least 1.5 metres.
9. A vent according to any preceding claim, in which in the venting configuration, the gas outlet is positioned at least 2 metres, preferably at least 2.5 metres from the base of the vent, or from a surface on which the vent is standing.
10. A vent according to any preceding claim, comprising a valve for permitting or preventing flow of a gas through the conduit.
11. A vent according to any preceding claim in which the gas inlet and gas outlet are at opposing ends of the conduit, the gas inlet being at a first end of the conduit and the gas outlet being at a second end of the conduit.
12. A vent according to any preceding claim, in which the gas outlet is adapted for engaging with a gas hose.
13. A vent according to claim 12, in which the gas inlet comprises a threaded external surface for engaging with a correspondingly threaded internal surface of the gas pipe or gas hose.
14. A vent according to any preceding claim in which the conduit comprises a gas testing point positioned between the gas inlet and the gas outlet, the gas testing point for permitting expulsion of gas from the conduit.
15. A vent according to any preceding claim in combination with a hose, the hose having one end that is attached, preferably releasably attached to the gas inlet.
16. A kit, comprising: a vent as defined in any of claims ito 15; and a gas hose attachable to the inlet of the conduit.
17. A gas main or service vent for venting gas from a gas main or service pipe, comprising: a conduit having a gas inlet for receiving gas from the gas main or service pipe and a gas outlet for venting gas from the gas main or service pipe into the atmosphere, the conduit being positionable in a venting configuration in which the gas outlet is at a pre-determined height, in which the vent is in combination with a hose, the hose comprising a first end that is attached, preferably releasably attached, to the gas inlet and a second end that is adapted for attaching to a gas main terminal.
18. A vent according to claim 17, comprising an integral stand for supporting the vent in the venting configuration, or in which the conduit is specifically adapted to engage or attach to a stand for supporting the conduit in the venting configuration.
19. A method for venting gas from a gas main or service pipe, comprising: positioning a gas main vent away from a gas main or service pipe terminal, the vent comprising a conduit having a gas inlet for receiving gas from the gas main or service pipe and a gas outlet for venting gas from the gas main or service pipe into the atmosphere; configuring a venting configuration, in which the gas outlet is at a pre-determined height; and connecting a first end of a hose to the terminal and connecting a second end of the hose to the gas inlet of the vent.
20. A method according to claim 19, comprising configuring or attaching a stand such that the stand supports the conduit in the venting configuration.
21. A vent substantially as hereinbefore described with reference to the accompanying drawings.
22. A kit substantially as hereinbefore described with reference to the accompanying drawings.
23. A method substantially as hereinbefore described with reference to the accompanying drawings.Amendments to the claims have been filed as follows Claims 1. A portable gas main and service vent for venting gas from a gas main or service pipe, comprising: a conduit having a gas inlet for receiving gas from the gas main or service pipe and a gas outlet for venting gas from the gas main or service pipe into the atmosphere, the conduit being positionable in a venting configuration in which the gas outlet is at a pre-determined height; and a stand for supporting the conduit in the venting configuration, in which the stand is integral or is releasably attachable to the conduit.2. A vent according to claim 1 in which the stand is collapsible.3. A vent according to claim 1 or claim 2, in which the stand comprises a plurality of legs, preferably three legs.4. A vent according to claim 3, in which the legs are hingedly attached to cf the conduit.tiC) 20 5. A vent according to claims 3 or claim 4, in which the legs are configurable between a first state and a second state, the first state characterised by the legs being substantially parallel to a longitudinal axis of the conduit, and the second state being characterised by the legs radiating from the conduit.6. A vent according to claim 5, in which the legs are lockable or retainable in the second state.7. A vent according to claim 5 or 6, in which the conduit comprises a plurality of housings into which an end of each leg can be secured.8. A vent according to any of claims 3 to 7, in which each leg has a length of at least 1 metre, preferably at least 1.5 metres.9. A vent according to any preceding claim, in which in the venting configuration, the gas outlet is positioned at least 2 metres, preferably at least 2.5 metres from the base of the vent, or from a surface on which the vent is standing.10. A vent according to any preceding claim, comprising a valve for permitting or preventing flow of a gas through the conduit.ii. A vent according to any preceding claim in which the gas inlet and gas outlet are at opposing ends of the conduit, the gas inlet being at a first end of the conduit and the gas outlet being at a second end of the conduit.12. A vent according to any preceding claim, in which the gas inlet is adapted for engaging with a gas hose.13. A vent according to claim 12, in which the gas inlet comprises a threaded external surface for engaging with a correspondingly threaded cf internal surface of the gas hose.tX') 20 14. A vent according to any preceding claim in which the conduit comprises a further gas outlet positioned between the gas inlet and the gas outlet.15. A vent according to any preceding claim in combination with a hose, the hose having one end that is attached, preferably releasably attached to the gas inlet.16. A kit, comprising: a vent as defined in any of claims ito 14; and a gas hose attachable to the inlet of the conduit.17. A method of purging or venting gas from a gas main or service pipe, comprising: obtaining a vent, as defined in any of claims ito 15; configuring the venting configuration of the vent; attaching the vent to a gas pipe terminal; and permitting gas flow from the gas pipe terminal to the vent.18. A method according to claim 17, comprising attaching a first end of a hose to the gas inlet of the vent and attaching a second end of the hose to the gas pipe terminal.19. A vent substantially as hereinbefore described with reference to the accompanying drawings.20. A kit substantially as hereinbefore described with reference to the accompanying drawings.21. A method substantially as hereinbefore described with reference to the accompanying drawings.LO r