ACD Machine Control offers Vibration Meter/Data Logger. Model D-83 reads displacement of vibration in microns pk-pk. However, to decide severity or acceptance level of vibrations from displacement, one has to know the operating speed. In Model D- 93, apart from displacement also reads velocity of vibration in mm/sec pk. This reading is obtained by differentiating displacement with reference to the frequency, Hence, it directly denotes the severity and one does not need to refer to the operating speed to decide the acceptance level. This instrument is battery operated and very convenient to handle.