IES86125B2 - Improved overblow cable installation method and apparatus for installing cables in a conduit - Google Patents

Abstract

An adapter chamber configured to be connected to a blowing machine for introducing a second cable and optionally, a third cable, into a conduit in which a first cable is already provided, the adapter chamber comprising first slot means for receiving the first cable and second slot means for receiving the second cable; and optionally a third slot for receiving the third cable. A method of installing a second, third or subsequent cable in a conduit in which a first cable was already provided, the method comprising the following steps: (a) cutting the sub duct at the start point of the proposed new ducting route for the additional cable so as to allow the insertion of the second cable and optionally, third cable, through the sub duct;(b) positioning an adapter chamber at or on the blowing machine; and (c) introducing air under pressure directly into the sub duct using an adapter chamber configured to deliver the air under pressure thereby resulting in an air pressure effective for delivery of the additional cable(s) into the sub duct. <Figure 1>

Description

IMPROVED OVERBLOW CABLE INSTALLATION METHOD AND APPARATUS FOR INSTALLING CABLES IN A CONDUIT The present invention concerns improvements in and relating to a method and an apparatus 5 for installing at least one cable in a conduit; more particularly, the present invention concerns an improved method and apparatus for installing a second or third or subsequent cable(s) in a conduit which is already carrying a first cable therein.

Throughout this specification, it is to be understood that reference to installing a second cable io is to be construed as meaning a second, third, fourth or fifth or higher number of cables in a conduit which is already carrying a first cable.

It is also to be understood that the term cable includes fibre cable as well as tubes, tubing, pipes and piping.

Where there is a duct blockage or congestion in a duct route carrying cables, the current solution is to either locate, excavate and clear the blockage, de-silt, etc. or provide a duct overlay, the latter requiring the laying of new ducts and sub ducts. All currently known solutions are costly and time consuming, and there can be delays in resolving the problem because of these factors. The known solutions generally require opening notices and traffic management. The resulting disruption to traffic flow, pedestrian safety issues and the general public can cause significant economic impact.

While blowing methods are known for introducing a first cable into a conduit using air under pressure so as to carry the first cable into the conduit, no method is known for introducing an additional cable i.e. a second, third or further cable into the conduit using an overblowing methodology.

The present invention seeks to alleviate the disadvantages associated with the prior art.

In a first aspect, the present invention provides an adapter chamber configured to be connected to a blowing machine for introducing a second cable into a conduit in which a first cable is already provided, the adapter chamber comprising first slot means for receiving the first cable and second slot means for receiving the second cable.

Preferably, the adapter chamber also comprises third slot means for receiving a third cable.

Preferably, the adapter chamber is generally in the form of an elongate cylinder when assembled from its component parts. The adapter chamber comprises a front collet unit, a main body and a rear collet unit.

Advantageously, each of the front collet unit, a main body and the rear collet unit are formed from two separable members which are engageable together. Thus, ideally, the front collet unit comprises an upper front collet unit member and a lower front collet unit member; the main body comprises an upper main body member and a lower main body member; and the rear collet unit comprises an upper rear collet unit and a lower rear collet unit.

Advantageously, the adapter chamber of the present invention includes an air entry port for introduction of air under pressure into the adapter chamber and preferably, the air entry port is provided on the main body of the adapter chamber.

The air entry port is preferably set at an angle so that the airflow is directed on a natural path towards the existing duct and, ideally the air is introduced into the adapter chamber at an optimum air pressure of 12 bar for delivery of the pressurised air at the optimum pressure of 12 bar into the duct. The adapter chamber is configured to be connected on or to a cable blowing apparatus such that the adapter chamber is positioned, for installing cable(s), at or on the blowing machine which is known in the art.

In a second aspect, the present invention also provides a method of installing a second, third or subsequent cable in a conduit in which was already provided a first cable, the method comprising the following steps: (a) cutting the sub duct at the start point of the proposed new ducting route for the additional cable so as to allow the insertion of the second cable and optionally, third cable, through the sub duct: (b) positioning an adapter chamber at or on the blowing machine; and (c) introducing air under pressure directly into the sub duct using an adapter chamber configured to deliver the air under pressure thereby resulting in an air pressure effective for delivery of the additional cable(s) into the sub duct.

Preferably, before step (a) is carried out, a testing procedure is carried out to check that any existing couplers provided along the sub duct are intact and are not leaking; advantageously, the testing procedure comprises introducing pressurized air at a pressure of 1 to 2 bar of pressure to confirm that the section of sub duct in question is intact. Any existing sub duct couplers that fail this testing procedure by showing leaks are replaced at this stage of the process.

The method preferably comprises the following steps: • The existing sub duct is cut to allow the insertion of the new fibre cable (i.e. the second cable) through the adapter chamber of the present invention at the start of the proposed new route.

• The fibre cable is then blown in alongside the existing fibre cable.

• The sub duct is then closed, leaving the new fibre ready for connection to the required service. Advantageously, the sub duct(s) and cables are then sealed by use of a duct seal such as grommet, connector, shrink or foam methods.

Accordingly, the applicant has developed a unique method of installing additional cable(s) into a sub duct that has an existing cable already within said sub duct. In accordance with the original product design, one cable was installed per sub duct; now the present invention has the significant advantage that it enables the same original sub duct to be used to carry a second and optionally, a third cable without having to replace the original sub duct and without having to insert additional sub ducts which would involve huge expense and disruption.

Whereas traditional methods of blowing fibre cable/tubes into a duct or sub duct involve the introduction of the compressed air at the blowing machine, the applicant has developed a method of introducing the compressed air directly to the sub duct using the specifically designed adapter chamber of the present invention, thereby achieving substantially no loss of pressure between the point of introduction of the pressurized air and the sub duct further downstream from the introduction point and thereby achieving increased the air pressure in the sub duct than previously obtained by the prior art methods which were concerned with introduction of only a first cable. Therefore, in accordance with the method of the present invention, there is sufficient air pressure available for installing the additional cable(s) (i.e. the second, third or subsequent cables) into the sub duct.

The success of the instaliation operation is dependent on certain criteria being met with regards to the internal diameter of the sub duct versus the external diameter of the existing and new cable(s).

Method of installing additional cables: Sub duct testing and purging.

In order to carry out a successful installation, the sub duct must first be tested for continuity 20 and to check the condition of any existing couplers to ensure that any existing couplers provided along the sub duct, are intact. This testing for continuity is achieved by introducing pressurized air at a pressure of 1 to 2 bar of pressure to confirm that the section of sub duct in question is intact. Any existing sub duct couplers that fail this testing procedure by showing leaks are replaced at this stage of the process.

The air pressure is gradually increased to between 3 and 4 bar to purge the sub duct of any materials, water or lubricant which may be present.

The sub duct test is now successfully completed.

The installation of the new fibre optic cable utilizes blown fibre methodology. The blown fibre system operates on the viscous drag principle employing cooled and dried air only, to install the cable, controlled and assisted by a hydraulically powered belt drive.

Sequence of steps: The cable is propelled by air and fed into the sub duct in which an existing cable is already provided, said cable having been inserted in the sub duct some time previously. The cable is propelled by air and fed in to the previously cabled sub duct via the Overblow unit having a belt drive system for controlling the fibre optic cable. The applicant utilises this Overblow unit as a means of inserting the cable into the sub duct. Due to the cable being floated by air introduced into the sub duct and propelled by the blowing machine belts only, the newly introduced second cable poses no risk to the existing cable. This method of installation in accordance with the present invention has the advantage that it eliminates the possibility of friction, wrap or burn damage to the existing cable associated with traditional cabling methods.

During the installation process, radio communication will be carried on constantly between site operators who are positioned at the locations of each of the adapter chambers of the present invention provided at the entry and exit points along the sub duct. In the unlikely event of movement on the existing cable, as detected visually by the operator in attendance at the cable exit point and the use of reference markers on the cables, the installation process of the second cable will be stopped immediately. The blowing machine is equipped with an emergency stop button which can be manually operated and, as an additional security precaution, the blowing machine will also automatically stop if pressure is detected on the cable being installed. The second cable (and the third cable, if a third cable is being installed) passes through the drive belts (cable pusher) on the blowing machine, the drive belt mechanism is rated to stop if the rate of speed of the second cable (and the third cable, if applicable) being installed begins to slow or decrease. This function acts as a fail safe to protect the second cable and the third cable when being installed. The third cable is installed subsequent to the second cable being installed and being in position in the sub duct.

Installation of the second and third cables in tandem would cause these cables to wrap or intertwine within the existing duct and the operation to fail. The installation of the third cable is carried out in the same way as the second cable with the same due care and attention taken as to not cause damage to the existing cable(s).

All plant and equipment is fit for purpose, and is within calibration and is checked prior to commencing the installation process.

The cable blowing equipment includes an air compressor, a cable blowing machine, a cable drum trailer and a cable fleeting device.

Only clean, dry, oil-free and cool compressed air may be used for installing cable in the sub duct(s).

The air compressor is fitted with air coolers, condensation separators and air filters.

The cable blowing machine comprises a cable pusher, mounted on an anti-corrosion treated, sturdy, height adjustable, wheeled, tubular steel trolley. The cabling blowing machine has a separate power pack which is preferably a petrol powered hydraulic power pack.

Previously, when installing a single cable in a sub duct, an air box was also required to be used in conjunction with the cable blowing machine. An air box is an adapter to allow air to be introduced into an empty sub duct to aid cable installation, the new and empty duct is damped at one side and the new cable enters through the other side and into the new duct, air is introduced through the top of the unit. Using the overblow method of the present invention, air is not introduced into an airbox on the blowing machine. Instead, completely different from the commonly held approach in the art,in accordance with the method of the present invention, air under pressure is introduced directly into the adapter chamber of the present invention by introducing air into an air entry port in the adapter chamber. This has the advantage that the compressed air (i.e. the air under pressure) is introduced directly to the sub duct which is held in the adapter chamber.

The cable blower/pusher has the following control means operable to control the cable blower/cable pusher: • Power On/Off Switch; • Emergency Stop Button; • Length Counter in Metres; • Cable Speed readout in Metres / m/h; • Hydraulic Pressure Readout; • Air Pressure Read out; · Hydraulic on/off control valve; • Adjustable speed control for drive belts; • Emergency Stop connection to the Hydraulic Power Pack which powers the blowing machine; and • Pre-set pressure relief valve and preset pressure sensor.

For operation of the cable installation process, the air compressor is positioned, where possible, to ensure the least impact on other road users. At the receiving end chamber, the contractor shall place a transparent cover, preferably made of Perspex, over the chamber area to eliminate the possibility of the newly introduced cable making contact with any persons when the cable is exiting the sub duct or the escape of debris from the chamber. In addition, the meter count on the cable blowing machine will be monitored and the cable speed will be decreased as the cable reaches the end chamber. Site operators who are working at different locations at places along the length of the sub duct will be in radio contact at all times.

The cable blowing machine will be positioned in a suitable location in line with the proposed sub duct into which the second, third or subsequent cable is to be installed. The height and angle of the cable blowing machine are adjusted to suit site conditions.

At exit chamber for cable, specified activities 1 to 10 are performed as required in accordance with Best Practice and Health and Safety regulations. The Health and Safety steps to be adhered to include, for instance, obtaining a permit to work from the client, PPE etc. The appropriate sized transparent cover is inserted on the exit chamber to restrict escape of dust and/or debris from the sub duct.

' The cable is inserted into the cable blowing machine in accordance with the cable blowing machine manufacturer's operating instructions.

The cable drum is positioned 6 - 8m directly behind the cable blowing machine. The cable drum trailer is suitably leveled and restrained. Where possible, the cable drum trailer is positioned to ensure the minimum impact on other road users and in accordance with the traffic management plan.

The air compressor and the cable blowing machine are now activated. Gradually, the air pressure is deployed into the sub duct until the air is free flowing at the open end of the sub duct.

The cable blowing machine is then set to the on position and so that the cable is begun to be fed through the existing duct and such that the cable drum is rotated, the motion speed of the cable drum will be gradually increased.

The blowing machine metre counter will be monitored closely and the speed of cable insertion will be decreased as the cable nears the exit of the sub duct. The cable exit from the sub duct will be controlled by reducing the speed of the cable blower until cable presents itself at minimum speed in the exit chamber.

The newly inserted cable will be coiled and stored correctly in the end chamber.

If the cable is a through cable onto another section, protective yellow spiral wrap will be used to protect cable in the event that a new coupler and heat shrink is not fitted or required.

The overblow unit is then removed from the adapter chamber which is located at the start point of additional cable(s) and all existing sub ducts are re-coupled. If not coupled, yellow spiral protective wrap will be used on cables.

The present invention will now be more particularly described with reference to the accompanying drawings in which are shown, one embodiment of an apparatus for installing a second cable and a third cable in a sub duct in which a first cable is already located. The embodiment shown in the drawings can accommodate and be used to install a second cable and a third cable in addition to the existing cable already in place in the sub duct. However, it is, of course, to be understood that it is not essential that a third cable be installed as in some instances, only a second cable might be required to be installed; the apparatus shown in the drawings can be used to install a third cable, if this is required, in the conduit carrying the first cable.

Figure 1 is a perspective view of the adapter chamber when fully assembled; Figure 2 is a perspective view of the unassembled components of the apparatus showing the two members of each of the components, namely of the front collet unit, main body and the rear collet unit; Figure 3(a) is a perspective view of the front collet unit; Figure 3(b) is a plan view from above of the front collet unit of Figure 3(a); Figure 3(c) is a front view of a major face of the front collet unit of Figure 3(a); Figure 3(d) is a side view of the front collet unit of Figure 3(a); Figure 3(e) is a sectional view along the line A-A of Figure 3(a); Figure 4(a) is a perspective view of a rear collet unit; Figure 4(a) is a perspective view of the main body of the adapter chamber; Figure 4(b) is a plan view in partial section of the main body; Figure 4(c) is a sectional view of the main body; Figure 4(d) is a sectional view of the main body; Figure 4(e) is a sectional view of the main body; Figure 5(a) is a perspective view of the rear collet unit; Figure 5(b) is a plan view from above of the rear collet unit of Figure 5(a); Figure 5(c) is a front view of a major face of the rear collet unit of Figure 5(a); Figure 5(d) is a side view of the rear collet unit of Figure 5(a); Figure 5(e) is a sectional view along the line B-B of Figure 5(a); Figures 6 to 8 inclusive show the stages of the method of installing in a conduit, using the adapter chamber and method of the present invention; Figure 6 is a perspective view showing stage 1 of the process; Figure 7 is a perspective view showing stage 2 of the process; Figure 8 is a perspective view showing the final stage (stage 3) of the process; Figure 9 is a perspective view which is the same as in Figure 7 (stage 2 of the process) except that Figure 9 shows the adapter seals which are used to accommodate varying sizes of cables in the channels of the adapter chamber; and Figure 10 is a perspective view which is the same as in Figure 8 (stage 3 of the process) except that Figure 10 shows the adapter seals which are used to accommodate varying sizes of cables in the channels of the adapter chamber.

Referring to the drawings, the assembled adapter chamber for installing cables in a conduit in accordance with the present invention is indicated generally by the reference numeral 100.

The adapter chamber 100 is generally in the form of an elongate cylinder when assembled from its component parts. The adapter chamber comprises a front collet unit 10, a main body 20 and a rear collet unit 30.

Each of the front collet unit 10, the main body 20 and the rear collet unit 30 are formed from two separable members which are engageable together. Thus, the front collet unit 10 comprises an upper front collet unit member 11 and a lower front collet unit member 12; the main body 20 comprises an upper main body member 21 and a lower main body member 22; and the rear collet unit 30 comprises an upper rear collet unit member 31 and a lower rear collet unit member 32.

The main body 20 includes an air entry port 23 to enable air under pressure to be introduced into the adapter chamber. The air entry port 23 is set at an angle of 45’ to the vertical axis.

The front collect unit 10 also comprises apertures 14 for securing fixing means e.g. bolts therein so as to secure the front collect unit 10 together to the main body 20. Further fixing means 141 are provided at the upper front collect unit member 11, Further fixing means 141 are provided at the upper front collet unit member 11.

Further fixing means e.g. bolts or screws 24 are provided in the upper member of the main body 20; and further fixing means 34 are provided in the rear collet 30.

Channels 15, 16 and 17 are provided in the front collet unit 10. The channel 15 is adapted for receiving the first cable FC and the existing sub duct ED (i.e. the existing cable previously inserted in the sub duct); the channel 16 is adapted to receive the third cable TC therein. The channels 15, 16 and 17 are formed when the upper member 11 and the lower member 12 of the front collet unit are abutted together and engaged with each other. Each channel 15, 16 and 17 is formed when the respective channel slots 15a, 15b; 16a, 16b; and 17a, 17b are aligned to form the corresponding respective channel 15, 16 and 17.

Corresponding channels 25, 26, 27 are provided in the main body 20. Each channel 25, 26 and 27 is formed when the respective channel slots 25a, 25b; 26a, 26b; and 27a, 27b are aligned to form the corresponding respective channel 25, 26 and 27.

One relatively longer channel 3, provided in the rear collet unit with the relatively larger channel 35 for receiving the existing sub duct, being provided by a protruding collar 39 on the rear collet unit 30. The channel 35 is formed when the respective channel slots 35a, 35b; are aligned to form the corresponding respective channel 35.

Referring now to Figures 9 and 10, an adapter seal is indicated by reference numeral 90. 5 The adapter seal is used to accommodate varying sizes of cables within the channels of the adapter chamber. The adapter seal is generally in the form of an O-ring.

Referring now to Figures 6 to 10, the method of installing a second cable SC and a third cable TC in a conduit in which was already provided a first cable, FC will be desired. The method comprises the fol I owi ng steps: (a) cutting the existing sub duct ED at the start point of the proposed new ducting route for the additional cable so as to allow the insertion of the second cable SC and the third cable TC, through the sub duct ED; (fa) positioning the adapter chamber 100 at or on the blowing machine (not shown in the drawings); and (c) introducing air under pressure directly into the sub duct using the adapter chamber 100 configured to deliver the air under pressure thereby resulting in an air pressure at an optimum of 12 bar of pressure effective for delivery of the additional cable(s) into the sub duct. The pressurised air is introduced into the adapter chamber 100 by connecting the pressurised air source to the air entry port 23 on the main body 20 of the adapter chamber 100. In Figure 4, the pressurised air PA source is shown connected up to the air entry port 23.

Before step (a) is carried out, a testing procedure is carried out to check that any existing couplers provided along the sub duct are intact and are not leaking; advantageously, the testing procedure comprises introducing pressurized air at a pressure of 1 to 2 bar of pressure to confirm that the section of sub duct in question is intact. Any existing sub duct couplers that fail this testing procedure by showing leaks are replaced at this stage of the process.

The method preferably comprises the following steps: • The existing sub duct ED is cut to allow the insertion of the new fibre cable (i.e. the second cable FC) through the adapter chamber 100 at the start of the proposed new route; · The second fibre cable SC is then blown in alongside the existing fibre cable; (shown as first cable FC and existing sub duct ED in Figures 6 to 10) • The sub duct is then closed, leaving the newly installed second and third cables ready for connection to the required service. Advantageously, the sub duct(s) and cables w are then sealed by use of a duct seal such as grommet, connector, shrink or foam methods.

Once the second cable FC is installed and in position in the adapter chamber and in the sub duct, then the procedure is repeated so as to install the third cable TC using the same steps as above.

It will of course be understood that the invention is not limited to the specific details described herein which are given, by way of example only, and that various modifications and alterations are possible without departing from the scope of the invention as defined in the appended claims.

Claims (6)

CLAIMS:

1. An adapter chamber configured to be connected to a blowing machine for introducing a second cable into a conduit in which a first cable is already provided, the adapter chamber 5 comprising a first slot means for receiving the first cable and a second slot means for receiving the second cable; optionally wherein the adapter chamber also comprises a third slot means for receiving a third cable. 10

2. An adapter chamber as claimed in Claim 1 wherein the adapter chamber is generally in the form of an elongate cylinder when assembled from its component parts; optionally wherein the adapter chamber comprises a front collet unit, a main body and a rear collet unit; optionally wherein each of the front collet unit, a main body and the rear collet unit are formed from two separable members which are engageable together; 15 optionally wherein the front collet unit comprises an upper front collet unit member and a lower front collet unit member; the main body comprises an upper main body member and a lower main body member; and the rear collet unit comprises an upper rear collet unit member and a lower rear collet unit member. 20

3. An adapter chamber as claimed in Claim 1 or Claim 2 further including an air entry port for introducing air under pressure into the adapter chamber; optionally wherein the air entry port is provided on the main body of the adapter chamber; and optionally wherein the air entry port is preferably set at an angle, preferably an angle 25 of about 45 degrees.

4. A method of installing a second, third or subsequent cable in a conduit in which a first cable was already provided, the method comprising the following steps: (a) cutting the sub duct at the start point of the proposed new ducting route for the 30 additional cable so as to allow the insertion of the second cable and optionally, third cable, through the sub duct; (b) positioning an adapter chamber at or on the blowing machine; and (c) introducing air under pressure directly into the sub duct using an adapter chamber configured to deliver the air under pressure thereby resulting in an air pressure effective for delivery of the additional cabie(s) into the sub duct; optionally wherein before step (a) is carried out, a testing procedure is carried

5. Out to check that any existing couplers provided along the sub duct are intact and are not leaking; advantageously, the testing procedure comprises introducing pressurized air at a pressure of 1 to 2 bar of pressure to confirm that the section of sub duct in question is intact.

6. 10 5. An adapter chamber substantially as herein described with reference to and as shown in the accompanying drawings; and a method of installing a second, third or subsequent cable in a conduit in which a first cable was already provided, substantially as herein described with reference to the accompanying drawings.