Patent attributes
Fire-resistant coaxial cables are described as well as methods to manufacture them. The dielectric between the coax cable's central conductor and outer coaxial conductor ceramify under high heat, such as those specified by common fire test standards (e.g., 1850° F./1010° C. for two hours). The dielectric can be composed of ceramifiable silicone rubber, such as that having a polysiloxane matrix with inorganic flux and refractory particles. Because thick layers of uncured ceramifiable silicone rubber deform under their own weight when curing, multiple thinner layers are coated and serially cured in order to build up the required thickness. A sacrificial sheath mold is used to hold each layer of uncured ceramifiable silicone rubber in place around the central conductor while curing. The outer conductor can be a metal foil, metal braid, and/or corrugated metal. Another layer of extruded ceramifiable silicone dielectric or an outer wrap of ceramic fiber yarn surrounds the outer conductor and continues to insulate it from the outside if a low smoke zero halogen jacket burns away. Methods of testing and installation are described.
