| 摘要 |
The rod incorporates a sealing device enabling a part of the inside surface of the tube, extending along its length, to be isolated from adjacent zones. The sealing device comprises two assemblies (5, 6) spaced along the length of the rod and each consisting of an annular piston (26, 36) slidably mounted on the body (2) of the rod, and at least one annular seal (32, 42) interposed between the piston and a radial support flange (33, 43). Compressed air supplied to the piston (26, 36) enables the seal (32, 42) to be compressed and to undergo radial expansion.
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