| 摘要 |
The device according to the invention is characterised essentially in that it comprises a spacing piece 6 inserted between two flanges 4 and 5 connected to the pipe 1, a channel 7 passing right through the said spacing piece and emerging on one side in the said pipe, on the other side outside of the said pipe, a hole 19 made in the said spacing piece and emerging on one side in the said channel, on the other side outside of the said channel, and a plug 23 capable of moving in the said hole between two positions, one for blocking the said channel, the other for opening it. <IMAGE>
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