JPH01114813A - Fire resistant optical fiber cable - Google Patents

Abstract

PURPOSE:To prevent the breaking of an optical fiber and the increase in transmission loss at the time of a fire by holding non-combustile heat resistant fibers and optical fibers by retaining winding tapes in grooves provided longitudinally on the outside peripheral face of a wire-shaped body and by covering the entire part with a fire-retardant sheath. CONSTITUTION:The spiral grooves 2 are provided to the outside circumference of the wire-shaped body 1 consisting of aluminum and the optical fibers 3 and buffer layer 4 consisting of carbon fibers are packed therein. The assembly is held by the retaining windings 5 of glass mica tapes. The entire part thereof is then covered by the fire-retardant polyethylene sheath 6. The optical fibers 3 consisting of the two layers formed with denatured silicone rubber plus silicone rubber on glass fibers or the fiber type coated with a UV resin are used. The optical fibers 3 are protected at the time of the fire by this structures and since no side pressures are exerted to the optical fibers 3, the breakage thereof is prevented and the increase in the transmission loss is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical fiber cable with a fireproof structure used in a disaster prevention management system for a building, etc.

(Conventional technology) Metal cables using copper conductors are used in disaster prevention management systems such as building alarm systems, but in recent years, as management systems have become more sophisticated, there has been an increasing demand for the use of optical fiber cables. . Regarding electric wires related to disaster prevention, standards for fireproof electric wires have been published by the Fire and Disaster Management Agency, and optical fiber cables are required to pass the above standards in the same way as conventional metal cables. However, to date, no optical fiber cable that meets this requirement is known.

(Problems to be Solved by the Invention) As an optical fiber cable with a fireproof structure, a conventional metal cable in which the copper conductor is replaced with an optical fiber can be considered. However, in this case, it was found that there was a new problem that did not need to be considered with metal cables. That is, when a prescribed fire resistance test was conducted, the cable components expanded during heating and lateral pressure was applied to the optical fiber, and this lateral pressure increased the transmission loss of the optical fiber.
It has also been found that the optical fiber breaks when the constituent materials burn.

(Means for Solving the Problems) Based on the above, the present inventor has developed a heat-resistant mia, such as glass fiber, that does not burn or decompose at high temperatures around the optical fiber.
proposed covering it with a buffer layer made of ceramic fiber, carbon fiber, and metal fiber (Utility Application No. 106280/1983).
This invention belongs to another proposal of the above-mentioned application, and its features include a linear body in which a spiral groove is carved in the length direction of the outer peripheral surface, and an optical fiber inserted into the groove. , a fire-resistant optical cable consisting of a buffer layer made of non-flammable heat-resistant fibers that covers the optical fibers inserted into the grooves, a presser tape that covers the optical fibers and the buffer layer, and a flame-retardant sheath that covers the entirety. In this way, it is nonflammable and heat resistant even in the event of a fire.
aIIi does not cause foaming due to melting or decomposition, and acts as a cushion and does not apply lateral pressure to the optical fiber.The above-mentioned pressure-wrapping tape may include glass mica tape, aluminum, in addition to the same nonflammable heat-resistant fiber as the buffer layer. Examples of the flame retardant sheath include a tape or a paper tape mixed with aluminum hydroxide, and flame retardant sheaths include flame retardant resins such as flame retardant polyethylene and vinyl, and aluminum laminate sheaths thereof.

(Example) The drawing shows an example of the fireproof optical fiber cable of the present invention, in which 1 is a linear body made of aluminum, 2 is a linear body made of aluminum;
3 is an optical fiber inserted into the groove 2, and 4 is carbon ta and Ii filled vertically into the groove 2 so as to cover the optical fiber 3. Buffer layer, 5 is optical fiber 3 and carbon #! a glass mica tape presser for holding the buffer layer 4 made of fiber;
6 is a flame retardant polyethylene sheath that covers the whole. The structure of the optical fiber 3 includes two layers of modified silicone rubber + silicone rubber or UvMI4 on top of the glass fiber.
Element wire type coated with oil, core wire type where these wires are coated with nylon etc., or wires made by twisting multiple of these wires or core wires, or multiple wires or core wires arranged in parallel. Examples include tape core wires that are entirely sheathed together, and even those in which multiple tape core wires are stacked.

Furthermore, if necessary, a tension member made of steel wire, FRP, or the like can be embedded, for example, in the center of the aluminum linear body or in the sheath.

(Experiment example) The above cable structure was made using a GI type optical fiber with epoxy acrylate UV resin coated on a silica fiber with Δ=1%, and a fire resistance test was conducted in accordance with JIS1304. The optical fiber was extremely excellent, with no increase in transmission loss or breakage, not only during heating but also during cooling.

(Effects of the Invention) As described above, in this invention, the optical fiber is covered with a non-flammable heat-resistant fiber, which not only protects the optical fiber in the event of a fire, but also acts as a cushion to put lateral pressure on the optical fiber. Therefore, the optical fiber can be prevented from breaking and an increase in transmission loss can be suppressed.

[Brief explanation of the drawing]

The drawing is a sectional view of a fireproof optical cable showing an embodiment of the present invention. In the figure, 1: linear body, 3: optical fiber, 4: nonflammable heat-resistant m#l buffer layer.

Claims (1)

[Claims] A linear body with a spiral groove carved in the length direction of its outer circumferential surface, an optical fiber inserted into the groove of this linear body, and a nonflammable heat-resistant material filled in the groove to cover the optical fiber. A fire-resistant optical fiber cable comprising a buffer layer made of fibers, a presser tape for holding the optical fibers and the buffer layer in a groove, and a flame-retardant sheath covering the entire cable.