Telephone duct

Telephone duct. [Data from Rapacki,S.R.,J. Vinyl Additive TechnoL, A, 1, 12-21, 1998. 

In very built up areas, telephone cables are laid in ducts that mostly consist of shaped duct blocks. This means that cables running parallel to tramway tracks cannot be avoided. Metal-sheathed cables with poor coating, or with none at all, are then heavily exposed to stray currents from the tramway [5,6]. 

Tape plastic over any windows in the room. Use duct tape around the windows and doors and make an unbroken seal. Use the tape over any vents into the room and seal any electrical outlets or other openings. Sink and toilet drain traps should have water in them (you can use the sink and toilet as you normally would). Push a wet towel up against the crack between the door and the floor to seal it. If it is necessary to drink water, drink the stored water, not water from the tap. Turn on the radio. Keep a telephone close at hand, but don t use it unless there is a serious emergency. 

In extrusion, the preheated material is forced out of the extruder with a screw (Figure 12-2) or double screw and allowed to cool in a bath or in the air. Thermoplasts, elastomers, and thermosets are extruded. As a rule, thermosets are processed in torpedo-containing extruders. With thermosets, most of the curing reaction must occur in a heated pressure chamber. Pressures can approach several hundred bars. The rate of extrusion is lowest with thick-walled bodies. Tubes are extruded at rates of up to 10 m/min, films up to 150 m/min, and telephone-cable insulating material or fibers at up to 1000 m/min. In extrusion, the Barus effect (Section 11.3.1) and melt fracture (Section 7.6.1) may be observed. Tubes, films, ducts, cable insulation, and knot-free nets are produced by extrusion. 

Fig. 13-4 Potential variation of telephone cables in a damp cable duct constructed of cable channel-shaped stone (without stray currents).

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