NL2016679B1 - Cable protection duct. - Google Patents
Cable protection duct. Download PDFInfo
- Publication number
- NL2016679B1 NL2016679B1 NL2016679A NL2016679A NL2016679B1 NL 2016679 B1 NL2016679 B1 NL 2016679B1 NL 2016679 A NL2016679 A NL 2016679A NL 2016679 A NL2016679 A NL 2016679A NL 2016679 B1 NL2016679 B1 NL 2016679B1
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- layer
- tube
- duct
- cable protection
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Abstract
The invention relates to a cable protection duct having a substantially circular duct wall extending along a longitudinal axis of the cable protection duct, characterized in that the duct wall, when seen in radial direction, has an inner polyethylene (PE) layer, an outer PE layer and a middle PE layer arranged in-between the inner PE layer and the outer PE layer, wherein the middle PE layer is made of recycled PE material. The invention also relates to a method for producing such a cable protection duct.
Description
Title: Cable protection duct FIELD OF THE INVENTION
The present invention relates to a cable protection duct having a substantially circular duct wall extending along a longitudinal axis of the cable protection duct. The present invention also relates to a method for producing such a cable protection duct.
BACKGROUND OF THE INVENTION
Cable protection ducts are known in a multitude of shapes, colours, lengths, et cetera. Such cable protection ducts are normally used to protect data communication cables, such as fibre-optic cables, from environmental hazards, such as mechanical damage due to forces being exerted on the cable, or from weather influences, such as rain or snow, or from groundwater corroding the cable. The same holds for extrusion processes typically employed to produce such cable protection ducts. Many types of processes are available to the skilled person to product such a cable protection duct. A problem with known cable protection ducts is that the C02-footprint resulting from the production of such ducts is relatively large. It takes a lot of resources -especially oil - to produce, for instance, a kilogram of PE. In the case of PE about 1.5 kg of oil is needed to produce a single kilogram of PE. Particularly for the production of cable protection ducts, which are typically relatively long, such as more than 10 m, more than 100 m, or even longer, large amounts of PE are needed. Furthermore, the extrusion process itself requires a lot of energy to produce a cable protection duct having the right properties, e.g. thickness, tensile strength, hardness, et cetera, further adding to the C02-footprint of the final product.
An object of the invention is thus to provide a cable protection duct that reduces the C02-footprint resulting from its production. A further object of the invention is to provide a cable protection duct that can be produced in such a way as to reduce the C02-footprint, wherein at the same time quality standards with respect to final product quality can be maintained.
SUMMARY OF THE INVENTION
Hereto, the cable protection duct according to the invention is characterized in that the duct wall, when seen in radial direction, has an inner polyethylene (PE) layer, an outer PE layer and a middle PE layer arranged in-between the inner PE layer and the outer PE layer, wherein the middle PE layer is made of recycled PE material.
The inventor has found that by having a middle PE layer of recycled PE material, the C02-footprint can be substantially reduced, whereas at the same time quality standards can be maintained. The three-layer cable protection duct as described above can be advantageously produced by employing a single three-layer extrusion process, saving substantially on the use of energy and allowing for reduced production times.
The inner and outer PE layers can be advantageously used to provide the cable protection duct with the desired “non-strength” related properties, such as smoothness, resistance to damage caused by UV irradiance, resistance to corrosion, oxidation, et cetera.
The middle PE layer is then primarily used to give the cable protection the required mechanical properties. Due to the middle PE layer advantageously not being visible because of the middle PE layer being covered “visually” by the inner and outer PE layers, it no longer matters that the middle PE layer is made of recycled PE material - which is usually less appealing aesthetically. Thus, it is no longer necessary to provide the PE material of the middle PE layer with a pigment. Furthermore, due to the inner and outer PE layers “shielding” the middle PE layer from the environment, it is no longer necessary to mix the respective additives with the PE material of the middle PE layer, further saving on production costs and further decreasing C02-footprint. Preferably, the PE concerns high-density polyethylene (HDPE).
An embodiment relates to an aforementioned duct, wherein the middle PE layer is free from pigment or wherein the middle PE layer is black. Thus, it is easier and cheaper to produce the aforementioned duct. It is thus conceivable that the middle PE layer retains the colours of the recycled PE pellets from which the middle PE layer is produced.
An embodiment relates to an aforementioned duct, wherein the thickness of the duct wall is approximately 3-10 mm, preferably 3-6 mm, such as 3.6 - 4.0 mm. With such duct wall thicknesses, the cable protection duct can be used in many different circumstances and at the same time a sufficiently thick middle PE layer can be employed to provide a substantially reduced C02-footprint.
An embodiment relates to an aforementioned duct, wherein the thickness of the middle PE layer is approximately 60 - 90 %, preferably 70 - 80 % of the (total) duct wall thickness. The inventor has found that for these thickness percentages, the gains to be made in terms of CC>2-footprint are most pronounced. Higher percentages would detract from the desired properties of the inner and outer PE layers, whereas lower percentages would only give marginal C02-footprint benefits and at the same time may lead to problems during extrusion of the middle PE layer.
An embodiment relates to an aforementioned duct, wherein the inner circumference of the inner PE layer is provided with grooves extending along the longitudinal axis of the cable protection duct. The grooves make it easier for a fibre-optic cable to be guided in particular through very long ducts.
An embodiment relates to an aforementioned duct, wherein the outer circumference of the outer PE layer has a smooth surface to further facilitate arrangement of the cable protection duct at its final operational location.
An embodiment relates to an aforementioned duct, wherein the inner and outer PE layers have the same colour to improve recognisability and visual attractiveness.
An embodiment relates to an aforementioned duct, wherein the inner, outer and middle PE layers have been formed by means of co-extrusion. Such a coextrusion process allows for fast production of the cable protection duct and at the same less energy is required for such a co-extrusion process, further reducing C02-footprint.
An embodiment relates to an aforementioned duct, wherein the outer diameter of the duct, i.e. measured at the outer circumference of the outer PE layer, is approximately 10-70 mm, preferably 16-63 mm, such as 40.1 - 40.4 mm. In practice the aforementioned outer duct diameter ranges provide for sufficient mechanical strength and at the same time allow a plurality of fibre-optic cables (having possibly varying outer diameters) to be arranged inside the cable protection duct.
An embodiment relates to an aforementioned duct, wherein the density of the PE material is approximately at least 900 kg/m3, preferably at least 940 kg/m3, to be able to produce a cable protection duct that allows for a wide range of recycled PE base materials to be used, whereas at the same time a cable protection duct having certain (minimum) mechanical properties can be realized. It should be noted that the recycled PE could be of lesser (or less consistent) quality than newly produced PE, but the inventor has found that by adopting the above values for the physical/mechanical properties of the duct (and the values mentioned hereafter) a cable protection duct of sufficiently consistent quality can be produced.
An embodiment relates to an aforementioned duct, wherein the melt index of the duct (2.16 kg - 190 °C) is approximately 0.4 - 0.8 g/10min, preferably 0.6 g/10min. This ensures that in case of severe heat exposure the cable protection duct protects the fibre-optic cable arranged inside the duct for a sufficiently long time before the duct melts away and/or its mechanical properties deteriorate to such levels that the fibre-optic cable can no longer be adequately protected.
An embodiment relates to an aforementioned duct, wherein the yield stress of the duct is approximately at least 10 N/mm2, preferably at least 15 N/mm2 to give the duct sufficient mechanical strength and margin for error in case the recycled material is of lesser quality.
An embodiment relates to an aforementioned duct, wherein the ultimate tensile strain of the duct is at least approximately 300%, preferably at least 350%, to allow the cable protection duct to lengthen considerably without damaging the fibre-optic cable arranged inside the duct.
An embodiment relates to an aforementioned duct, wherein the shore hardness of the duct is approximately at least 50 Shore D, preferably at least 60 Shore D, to give the duct sufficient resistance against mechanical deformation.
An embodiment relates to an aforementioned duct, wherein the melting point of the duct lies approximately at 120 - 140 °C, preferably at 126 - 132 °C. The inventor has found that in most cases these melting point ranges are sufficient to withstand any high temperatures to be encountered in practical situations.
An embodiment relates to an aforementioned duct, wherein the ductile-to-brittle transition temperature of the duct is lower than approximately -100 °C to allow the duct to retain sufficient ductility in a wide range of practical circumstances.
Another aspect of the invention relates to a method for producing an aforementioned cable protection duct, wherein the duct is formed by co-extruding the inner PE layer, the outer PE layer and the middle PE layer, wherein at least the middle layer is made of recycled PE material. Such a three-layer co-extrusion process saves a lot of energy and production time. The three layers are immediately and properly bonded together, providing very good adhesion thereof during the lifetime of the cable protection duct.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be explained hereafter with reference to an exemplary embodiment of a cable protection duct according to the invention and with reference to the drawing. Therein:
Figure 1 shows a schematic cross-sectional view of an embodiment of a cable protection duct according to the invention.
DETAILED DESCRIPTION
Figure 1 shows a cable protection duct 1 having a substantially circular duct wall 2 extending along a longitudinal axis X of the cable protection duct 1. The cable protection duct 1 is designed for the protection of cables used for telecommunication and preferably complies with the ‘direct buried’ requirements known in the respective industry. The duct wall 2, when seen in radial direction R, has an inner polyethylene (PE) layer 3, an outer PE layer 5 and a middle PE layer 4 arranged in-between the inner PE layer 3 and the outer PE layer 5, wherein the middle PE layer 4 is made of recycled PE material, such as HDPE. The middle PE layer 4 is preferably free from pigment or the middle PE layer 4 could be black. The thickness t of the duct wall 2 is approximately 3-10 mm, preferably 3-6 mm, such as 3.6 - 4.0 mm, as shown in figure 1. The thickness t4 of the middle PE layer 4 is approximately 60 - 90 %, preferably 70 - 80 % of the duct wall thickness t. The inner circumference 6 of the inner PE layer 3 is provided with several grooves 7 extending along the longitudinal axis X. The outer circumference 8 of the outer PE layer 5 has a smooth surface/finish, and is to be free from scratches, bubbles, et cetera. The inner 3 and outer 5 PE layers preferably have the same colour, such as blue or red, depending on client specifications. The inner 3, outer 4 and middle 5 PE layers have preferably been formed by means of co-extrusion. The outer diameter of the duct D0, i.e. measured at the outer circumference 8 of the outer PE layer 5, is approximately 10-70 mm, preferably 16-63 mm, such as 40.1 - 40.4 mm, as shown in figure 1. The cable protection duct 1 can be stored outside without further protection, if desired, provided the cable protection duct 1 will be arranged in its operational position within 6 months from its production date. Otherwise, the cable protection duct 1 is to be protected against direct sunlight (UV irradiation). The cable protection duct 1 can be stored on a reel and is to be provided with a sticker or label comprising descriptions of duct material, duct dimensions and duct length. The cable protection duct 1 according to the invention has an operational lifetime of at least 50 years under normal operational conditions. Thereto, it requires a minimum radius of curvature of 80.5 cm. Furthermore, the duct 1 should be arranged at a maximum depth of 1 meter above ground water level and should not be subjected to a tensile force of more than 3000 N. Maximum pressure is 16 bars, wherein during a period of 4 hours an internal water pressure of 20 bars can be withstood. Environmental temperature should lie between -10 °C and + 50 °C during installation and between -50 °C and +40 °C during storage. Moreover, external air pressure of 5 bars can be withstood for 1 hour. The above is in line with the NEN-EN 921 and ISO 1167 standards. To guarantee the protective properties of the duct 1, the duct 1 complies with the NEN-EN 744 standards.
It should be clear that the description above is intended to illustrate the operation of preferred embodiments of the invention, and not to reduce the scope of protection of the invention. Starting from the above description, many embodiments will be conceivable to the skilled person within the inventive concept and scope of protection of the present invention.
LIST OF REFERENCE NUMERALS 1. Cable protection duct 2. Duct wall 3. Inner PE layer 4. Middle PE layer 5. Outer PE layer 6. Inner circumference of inner PE layer 7. Groove 8. Outer circumference of the outer PE layer X. Longitudinal axis R. Radial direction t. Duct wall thickness t4. Thickness of the middle layer
Do. Duct outer diameter
Claims (17)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL2016679A NL2016679B1 (en) | 2016-04-26 | 2016-04-26 | Cable protection duct. |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL2016679A NL2016679B1 (en) | 2016-04-26 | 2016-04-26 | Cable protection duct. |
Publications (1)
Publication Number | Publication Date |
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NL2016679B1 true NL2016679B1 (en) | 2017-11-07 |
Family
ID=61022938
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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NL2016679A NL2016679B1 (en) | 2016-04-26 | 2016-04-26 | Cable protection duct. |
Country Status (1)
Country | Link |
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NL (1) | NL2016679B1 (en) |
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2016
- 2016-04-26 NL NL2016679A patent/NL2016679B1/en active
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