| 摘要 |
The present invention relates to a drill tube element (10; 10') for percussive top hammer drilling. The drill tube element (10; 10') according to the invention is provided with a valve means that functions as a non-return valve for the drilling fluid when drilling upwards with the drill tube element (10; 10'). When drilling in a direction in the range from horizontal to downwards the valve means admit drilling fluid to travel in direction towards the bottom of the hole that is being drilled.
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