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Title:
DEVICE TO GENERATE PRESSURE FOR DUCT SEALING
Document Type and Number:
WIPO Patent Application WO/2005/078883
Kind Code:
A3
Abstract:
The subject of the present invention is a multi-layer bag (1) composed by thermoplastic layers joined with suitable adhesives and metallic layers with a barrier function, in which the total contact between reagents parts, which provoke the inflating action of the bag, it is obtained applying vacuum inside the multilayer bag (1), forcing the reagent system in a stable and fixed position, providing the inner bag (5) which forms the reacting system, with a partial longitudinal or transversal welding (6) which circumscribes the area of the bag where reaction must take place, realizing a preferential breakage side, ulteriorly inner to the reagent system, containing the reaction liquid element.

Inventors:
GUARDASOLE MAURO (IT)
BIAN XINSHENG (IT)
Application Number:
PCT/IT2005/000063
Publication Date:
March 15, 2007
Filing Date:
February 10, 2005
Export Citation:
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Assignee:
ELCON MEGARAD S P A (IT)
GUARDASOLE MAURO (IT)
BIAN XINSHENG (IT)
International Classes:
H02G9/06; F16L55/134; H02G3/08; H02G3/22
Foreign References:
EP1217288A12002-06-26
US4846278A1989-07-11
US4621483A1986-11-11
Attorney, Agent or Firm:
SNEIDER, Massimo (Via Lucania 13, Roma, IT)
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Claims:

Claims 1) Device for ducts sealing composed by a mono or multilayer bag (1) in which it is contained an inner bag (5) inside which it is contained a collapsible bag (4) ; In the bag (5) the solid part is contained, and the liquid one in the bag (4), of a reacting system apt to release the gases able to inflate the bag (1), characterized by the fact that the reacting system made by the elements as bag (5) and bag (4) in its contained, and maintained in the desired position made by the void realized inside the bag (1), and that the bag (4) presents a side (3) with one side weaker then the other three, said mentioned low seal side being the breaking side of the bag (4) when submitted to pressure.
2) Device for duct sealing according to claim 1 characterized by the fact that the bag (5) presents a partial welding (6) in the transversal direction 3) Device for duct sealing according to claim 1 characterized by the fact that the bag (5) presents a partial soldering in the longitudinal (6) direction 4) Device for duct sealing according claims 1,2 and 3 characterized by the fact that bag (5) presents microholes (8) apt to consent the leakage of the gas generated by the reaction

between the solid part (8) contained in the bag (5) and the liquid one contained in the bag (4) 5) Device for duct sealing according to claims 1, 2 and 3 characterized by the fact that the bag (5) is provided with microporosis material apt to consent the leakage of the gas generated by the reaction between the solid part (8) contained in the bag (5) and the liquid one contained by the bag (4) 6) Device for duct sealing according to claims 1,2 and 3 characterized by the fact that the bag (1) shows, before the reaction, a swell (2) showing the point on which it is necessary to generate the pressure in order to start the reaction.

Description:

Device to generate pressure for duct sealing Technical field This invention concerns a device to generate pressure for duct sealing made by a bag, placed between the cable and the duct, once inflated, seal by means of pressure the free spaces in the ducts Description of related art It is known that cables networks, either in the electrical distribution or telecommunication, are equipped with cabinets in which connections between cables or between cables and various equipments, are realized.

These cabinets can be normally placed under ground, and the access of. the cables thorough their walls is exposed to water/moisture penetration if not properly sealed.

Generally plastic ducts are installed in the cabinets to allow the cables to pass through their walls and come inside the cabinets for the needed connections..

These plastic ducts, beyond humidity and water, can be as well entrance for gases coming from possible leakages or failures into the

gas distribution pipes, these gases saturating the cabinets can generate serious hazard.

Therefore the problem of sealing the cable ducts is very important.

Different systems have been used in the past, mainly based upon the application of sealants, without reaching satisfying solutions. Main problems are generated by the environmental stresses, like thermal variations and mechanical stresses, together with the actions of pulling and torsion which cables and relevant walls are subject to during their working life.

Similar considerations can be extended to pipelines ducts and other generic installations. Recently a system, so called active, has become popular.

It is made by a bag, inflatable at convenient pressure levels. This bag, placed between the cable and the duct, once inflated, seals by means of pressure, the free spaces in the duct, keeping a constant mechanical action against the different surfaces and absorbing all the stresses already mentioned.

The bag, made by a suitable multi-layer, is sealed at the edges and it is equipped by a valve for the inflation. The layers composing the bag have different characteristics, due to the different functions, like pressure withstanding or waterproofing.

The valve of such a bag is equipped by a"cannula"which allows the inflation from the outside, once properly installed in the duct.

in order to reach the necessary pressure for the duct sealing, different systems are used, among them for instance, a compressors or pressurized gas tanks.

Furthermore, it is necessary to use a manometer to measure the necessary sealing pressure; in fact, a lower pressure would not allow the correct functioning of the sealing system, while a higher pressure could damage the inner cables (i. e. optic fiber cables), or the welding parts of the sealing bag itself Moreover, as the inner duct surfaces may present some irregularities, like for example in case they are digged directly in the wall, without any plastic duct installation, it is convenient to apply all along the bag a piece of sealant mastic tape.

An efficient sealing is granted by the above mentioned mastic tape when compressed by the bag, against cable and the duct walls.

Anyhow, the active system above described presents some weak points: - the need of a compressor in loco for air inflation, or a pressurised tank in case of gases different from air, and a manometer - inflation should be made after placing the bag in the duct, often in an uncomfortable position which could affect the correct positioning of the bag inside the duct.

Other solutions have been recently proposed, for instance in patents FR-A 2-277006, EP-A 0-296-388, EP1-217-288A1 in which it is described, in general terms, a multi layers bag able to inflate when a

contact is provoked between two initially separated chemical components, which can develop gas by chemical reaction.

For what concern patent FR-A 2-277006, contact between the reagent elements is casual and partial, as it is linked to the positioning of liquid and solid parts after the setting, as well as per the Italian patent n° 081030763.7 and EP1-217288A1 where reagents are kept in separate chambers.

System described in EP 0296388 A1 is made by multiple chambers whose reaction is caused by the pressure generated by the the first reaction in the first reagent chamber; in this system it is essential the sequence intervention of the single components chambers, starting from the first and the reagent system is activated in the factory and sealed inside a spray cylinder.

Main inconvenient of the above mentioned solutions is the impossibility to obtain a programmable and certain inflating pressure in the bag, able to apply the sealing function required; the other inconveniences are as follows : - overall obstruction of the bag which seldom allows an easy application in the right places - difficulty to identify the exact point on the bag where it is necessary to apply the pressure in order to provoke the inflating chemical reaction.

Disclosure of the invention The subject of the present invention is a multi-layer bag composed by thermoplastic layers joined with suitable adhesives and metallic layers with a barrier function, able to eliminate the inconveniences previously described in which the total contact between reagents parts, which provoke the inflating action of the bag, it is obtained applying vacuum inside the multilayer bag, forcing the reagent system in a stable and fixed position, providing the inner bag which forms the reacting system, with a partial longitudinal or transversal welding which circumscribes the area of the bag where reaction must take place, realizing a preferential breakage side, ulteriorly inner to the reagent system, containing the reaction liquid element.

Brief description of the drawings The above and other characteristics of the invention in its main but not restricting production form will be herein after described, referring to the enclosed drawings in which: - Figure 1 shows a schematic view of cables and ducts configuration - Figure 2 shows a complete view of the device in which inner reaction system is displayed kept in the desired position by the soldering under vacuum

Figure 3 shows a schematic view of the bag containing the liquid part of the reagent system Figure 4 shows the bag containing the entire reaction system provided with a transversal septum Figure 4A shows the bag containing the entire reagent system provided with a longitudinal separator Figure 5 shows the bag containing the entire reaction system provided with a transversal septum and with holes to allow gas leaking, said reaction system fixed positioned, by vacuum, in the outer welded multilayer bag.

Description of a preferred embodiment of the invention The device is, in a preferred form, made by: - a first bag (4), approximately cylinder shaped, soldered by a heavy seal, on three sides one transversal and two longitudinal, where the necessary strength to break said solderings should be not less them 25 N/c. Fourth welding (3) is the one that is to be broken by pressure applied by operator fingers. Strength to be applied to break this soldering is preferably between values of 5 and 10 N/cm; this welding (3) is weaker than the other three previously described, so that the bag (4) containing liquid reagent is obliged to break exactly nearby.

- a second bag (5) constituting the reagent system in which the bag is contained (4); the bag (5) is provided with a partial welding (6), longitudinal or transversal, which contains in its inferior side the solid reagent (7) positioned nearby the weak welding (3) of the bag (4) - a third multilayer bag (1) which contains the reagent system, it means the bag (5) which itself contains the bag (4) with the collapsible side.

The bag (4) is positioned, as mentioned, inside the bag (5) so that the liquid which comes out after that the operator has provoked the breaking on the side (3) by finger pressure, is by all means totally in touch with solid part (7); reaction is provoked by the operator after that the self inflating multilayer bag (1) has been correctly positioned.

In order to allow the operating of the reagent device and the inflating of the multilayer bag (1) the bag (5) containing the reagent system is provided with little holes or with microporosis materials, apt to consent fast leakage of gas but not of the liquid before it has reacted with the solid part (7).

As already mentioned, in the device object of the present invention, it is compulsory that reaction develops after the installation, and that the bag (1) is, before the reaction, as totally empty for a correct application, a part from a slight swelling (2) which shows the point where the operator has to press and provoke the breaking of the weak

side (3) of the bag (4) containing the liquid part and consequently the reaction which allows its inflating.

I some cases, in order to control as much as possible the dimensions of the self inflating bags (1) suitable for many different ducts and cables configurations, the reaching of operating pressure inside the bag may be obtained starting from a standard volume v1 engaged by the bag in connection with a certain pressure p1, chosen for a particular cables/duct configuration and changing the volume available in the bag by one or more solid cylinders, to be introduced beside the cables, in order to reduce the mentioned volume and therefore increasing the operating pressure according to the mentioned reaction Pv=k In this way, a single bag (1), with the intervention of the indicated cylinders, may be suitable for many different cables/ducts configurations.

As a not limiting example, we indicate that, in case the substances in the system were citric acid and sodium bicarbonate, the pressure to obtain in case of fig. 1 configuration, where duct diameter was 90mm and duct diameter 35mm, it would be 2.35 atm.

This result can be reached by using 4.4 gr of sodium bicarbonate and 18.0 mi of a solution made at 40% weight of citric acid in water.

In case of fig. 1 configuration with duct diameter 75mm and cables diameter 22mm each, pressure to be obtained would be 3 atm,

attainable with 3.1 gr of sodium bicarbonate and 13mut of a solution made at a 40% of citric acid in water.

As the application of the self inflating bag (1) will be handled by many operators, and as it is necessary to install the bag correctly around cables and ducts, it is obvious that it will be submitted to a remarkable handling. The void obtained will reduce the multilayer bag to a thin foil, providing an easier installation, as well as maintaining the reagent system, in a safe and irremovable way, in the required position, so that it is possible to provoke its rupture by fingers pressure. Furthermore, the stable position could be obtained also using adhesives or soldering inside the external bag.