Tube for the circulation of a flammable fluid, and conduit made

Details Tube for the circulation of a flammable fluid, and conduit made Tube for the circulation of a flammable fluid, and conduit made

1989-02-07

1991-01-15

Pellinen, A. D.

Electricity: electrical systems and devices

Discharging or preventing accumulation of electric charge

Of storage or hazardous area or fluid handling

174 70R, 174 78, H05F 300

Patent

active

049858017

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a tube for the circulation of a flammable fluid, as well as to a conduit made from such tubes.
2. Background Art
The invention is particularly, but not exclusively, applicable to the tubes for the circulation of fuel in aircraft of which numerous structures, such as the tanks, are made at least partially of insulating composite material.
When a metallic fuel circuit is installed in a totally or partially insulating structure, such as a fuel tank made of composite material, and when said structure is struck by lightning, a considerable current of lightning risks circulating in the conduit which is a better conductor of electricity than the surrounding structure. This phenomenon presents considerable risks due to overheating or to sparks which may be produced at the different joints between conduit elements, during passage of the current.
Furthermore, the conduit of the fuel circuit must satisfy two requirements. The first is that of withstanding the mechanical efforts produced by the fuel or the deformations of the structure in which it is mounted. The second is that of evacuating the static electricity created by the circulation of the fuel - electrically insulating - at high speed in the conduit. These two functions are generally ensured when the tube is made of metal, which, on the other hand, presents, as has been seen hereinabove, risks in the event of the aircraft being struck by lightning.


BROAD DESCRIPTION OF THE INVENTION

It is an object of the invention to avoid these drawbacks, and it relates to a tube for the circulation of a flammable fluid, such as fuel, of which the design makes it possible to prevent the currents of lightning from circulating in the conduits made from said tubes, while making it possible to bleed off the static electricity, generated by the circulation of the fuel, towards the conductive zones of the tank, and respecting the mechanical stresses connected with the circulation of the fuel or with the deformations of the structure in which said tubes are mounted.
To that end, the tube for the circulation of a flammable fluid, adapted to be mounted in a structure, made at least partially of electrically insulating material, capable of being subjected to electrical disturbances of atmospheric origin, said tube comprising two endpieces for joining of electrically conductive material and a body, is noteworthy, according to the invention, in that the tube body, of which at least the inner face is electrically conductive over the major part of its length, presents at least one electrically insulating section.
In this way, the invention creates, in the tube, at least one local non-conductive zone, which avoids the conduit for circulation of the flammable fluid, particularly fuel, constituting a continuous conductor for the currents of lightning. Furthermore, the major part of the tube is conductive and may be connected to the conductive zones of the structure, or of an adjacent structure, to bleed off the static electricity.
According to a first embodiment of the invention, the tube body is made of an electrically insulating material, and the inner face of said body comprises two electrically conductive elements, separate from and connected to said endpieces, respectively.
In particular, said conductive elements are disposed symmetrically with respect to an electrically insulating, central section of the body of the tube.
According to a second embodiment of the invention, the tube body is constituted by two end sections made of electrically conductive material and connected to an electrically insulating, intermediate section.
In particular, said intermediate section is constituted by two insulating sleeves, of which one is disposed inside said end sections, and the other, outside.
According to other features of the invention, said electrically insulating material is a composite material, and the parts of said tube made of electrically conductive material are grounded.


BRIEF DESCRIPTION OF THE

REFERENCES:
patent: 1516422 (1924-11-01), Dallenbach
patent: 3828112 (1974-08-01), Johansen et al.
patent: 3943273 (1976-03-01), de Putter
patent: 4108701 (1978-08-01), Stanley
patent: 4215384 (1980-07-01), Elson
patent: 4654747 (1987-03-01), Covey
patent: 4697300 (1987-10-01), Warloq

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