amplitude and frequency of the vibrations at the respective measurement position furthermore the measuring equipment comprises a current generator 211 for feeding current to the accelerometers 207 208 209 and 210 filtering means 212 for filtering the signals received from the accelerometers 207 208 209 and 210 and sampling means 213 for sampling the filtered signals the device comprises a control device 214 which is connected to the current generator 211 the filter means 212 and the sampling means 213 from which the control device 214 receives the sampled signals furthermore the control device 214 is connected to three adjusting means 215 216 and 218 for advantageously adjusting the refining surface 204 of the stator 206 the adjusting means 215 216 and 218 being evenly distributed around the circumference the control device 214 comprises comparison means 217 for comparing the measurement results of the accelerometers 207 208 209 and 210 with each other and correct alignment is established if these measurement results are substantially equal the control device 214 is arranged to control the adjusting means 215 216 and 218 for adjusting the refining surface 204 of the stator 206 based on the comparison by the comparison means 217 until substantially equal measurement results are obtained from the four vibration sensors 207 208 209 and 210 whereby correct alignment between the refining surfaces 203 and 204 is attained the measuring equipment 207 208 209 210 211 212 and 213 the comparison means 217 and the adjusting means 215 216 and 218 are arranged to perform this measurement comparison and adjustment during operation fig3 shows a front.