Nkf Kabel B.v.

Frans Robbert Bakker

Willem Griffioen

Pieter Lock

Willem Greven

Arie Van Wingerden

Cornelis Van 't Hul

David F Hawkins

Gerard Plumettaz

Cornelis Van &prime;T Hul

A method for installing branches in a protective ducting system in which guide tubes and cables have already been laid, wherein at a desired branch location in the protective duct, a splittable Y-branch connector with an inlet opening, an outlet opening and at least one branch opening is installed by cutting a short section from the duct at the desired branch point and exposing the guide tubes and cables, opening the splittable branch connector and arranging it around the exposed guide tubes and cables, and closing and securing the Y-branch connector with splittable coupling collars in such a manner that the inlet opening and the outlet opening engage in sealing manner over the respective cut ends of the existing duct, and the branch opening of the connector is secured by engagement of a branch stub around a branch duct through which a branch guide tube is laid.

Method of installing Y-branch splittable connector

A filling body is inserted together with a loose bundle of guide tubes during installation into the passage space of a protective duct, thus enlarging the bundle diameter (which reduces the buckling risk) and making crossing of the guide tubes impossible. The guide tubes are positioned along the outside of the filling body, providing access to the guide tubes during post-installation branching. The filling body may include radially projecting spacer ribs that separate the guide tubes, thereby preventing crossing movement and helical stranding. The guide tubes are thus constrained and carried along with the filling body in alignment with the spacer ribs, so that buckling, helical stranding and three-dimensional restrictions or tangles cannot occur.

Installation bundle with spacer

A filling body is inserted together with a loose bundle of guide tubes during installation in an existing protective duct, thus enlarging the bundle diameter (which reduces the buckling risk) and making crossing of the guide tubes impossible. The guide tubes are positioned along the outside of the filling body, providing access to the guide tubes during post-installation branching. The filling body may include radially projecting spacer ribs that separate the guide tubes, thereby preventing crossing movement and helical stranding. The guide tubes are thus constrained and carried along with the filling body in alignment with the spacer ribs, so that buckling, helical stranding and three-dimensional restrictions or tangles cannot occur. The filling body may include a thin tubular sidewall enclosing a longitudinal airflow passage that may be pressurized during installation, and deformable when unpressurized, thus providing mechanical protection against damage of the protective duct after installation.

A cable straightener removes mini-bends from cable as it is unwound from a reel for installation in an underground duct, providing improved blowing performance for any cable with non-negligible stiffness and that exhibits reel-set or shape memory recovery, for example cables enclosed within small diameter tubular steel jackets, cables enclosed within aluminum laminated polymer sheets, and cables enclosed within hard polymer tubing. Residual stresses induced in such cables are reduced by first and second sets of straightener rollers prior to pushing/blowing installation.

Optical cable installation with mini-bend reduction

An existing protective duct contains a bundle of guide tubes through which fiber optic cables are run to customers at existing service locations. In order to run a cable to a new customer at a different service location, the duct is cut at a branch point and a short section of the duct is removed to expose the guide tubes. An unused guide tube is cut and serially connected to a branch guide tube leading to the new service location. The protective duct sidewall is restored at the branch point by a splittable Y-branch connector that includes complementary housing sections, an inlet opening, an outlet opening and at least one branch opening. Splittable coupling collars seal the branch connector housing sections around the respective cut end portions of the existing duct. The Y-branch connector also includes a branch stub that is sealed around the branch guide tube.

Y-branch splittable connector

Guide tubes are arranged in a loose bundle and are fed into an existing tubular conduit or protective duct by a powered tractor and are pulled through the duct by the volumetric flow of compressed air which is introduced into the inlet end of the duct. The guide tubes are pressurized and closed at their leading end and trailing end. The existing duct is open at both ends. When the filling degree of the guide tube bundle (sum of guide tube cross-sectional areas compared to that of channelization duct) is provided in the range of from about 30% to about 60%, blowing/pushing installation of the guide tube bundle is substantially trouble free, and the bundle of guide tubes can be installed in a flexible and efficient manner over relatively greater distances.

Growing community of inventors

Wagenborgen, Netherlands

Frans Robbert Bakker