| 摘要 |
<PICT:0760758/III/1> <PICT:0760758/III/2> A method of impregnating and lining a conduit having porous walls comprises clamping the conduit firmly in a sectional mould of resilient material, filling the conduit with a sluggishly flowable compound, sealing one end of the conduit and injectadditional compound into the conduit through a connection at the other end of the conduit, under pressure sufficient to force the compound through the porous walls and between engaged surfaces of the mould sections. A conduit comprises a series of braided wire tubes, the ends of which are soldered together and into metal ferrules 18 which are in turn soldered in end members 11, 12 so as to abut flanges 20, 21. The inner surface of the conduit is treated with a suitable primer, such as "Unochrome 219 PX" (registered Trade Mark) for a nickel tube. The conduit is dried and cooled and clamped in a close fitting resilient sectional mold 30 which may comprise a neoprene compound such as Scinflex. The mold and conduit are then clamped between a fixed side wall 31 and a movable side wall 32 to which air, fluid or mechanical pressure is applied. A compound such a plastisol is introduced into the conduit by a fitting 33 having a gasket 34 pressed against the flange 20 to provide a seal. A suitable compound comprises - ten parts by weight of polyvinylchloride such as "Geon 121" (Registered Trade Mark) four parts by weight of "Rohm and Hass Paraplex G-50" (Registered Trade Mark) two parts by weight of Paraplex G-60 and two parts by weight of a heat stabilizer consisting of a mixture of Paraplex G-50 and dibasic lead phthalate in equal parts, all components being mixed thoroughly preferably under vacuum. When plastisol emerges from the end of the conduit it is sealed by a plug 35 and the plastisol is continued to be introduced until it emerges from between the mold sections 30. The conduit is removed from the mold, and drained in a vertical position until the central aperture is large enough to receive an insulated conductor of the desired size. The conduit is then baked in an oven at a temperature of 350 DEG to 400 DEG F. for a short time until the plastisol is set to a weak gel. The conduit is cooled and excess plastisol removed. The conduit is baked again at about the same temperature until the plastisol is thoroughly cured and set. The conduit may be used as a flexible, non-porous conduit for radio shielding an electrical conductor.
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