| 摘要 |
When a tube is laid in a duct by a blowing process, the extremity of the tube first introduced in the duct is fitted with an end cap fastened in an airtight fashion on said extremity and fitted with a valve suitable to control the pressure Pint inside the tube, so that is always greater than the pressure Pext in the duct. In this matter, deformations or implosions of the tube are avoided.
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