| 摘要 |
In connection with rock drilling it is necessary to control the airflow through the drill bit in question. The pressure of the flushing air is measured in a reference area in order to mathematically calculate nominal and corrected airflow values through the drill bit with the aid of said pressure. According to the invention, existing nozzles (8) and/or channels (11) in the drill bit are utilised as a reference area for pressure measurement, and the real pressure is measured with the aid of a measurement means (14) which comprises a narrow tube (15) communicating with a manometer, which tube with an orifice is inserted into one nozzle (8) of the drill bit.
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