With this measuring principle, a small part of the flow is passed through a bypass. This small flow quantity ends up in the measuring cell via this by-pass. In the measuring cell, the medium flows through a chamber with two channels. The flow causes an under and over pressure in the measuring cell, causing the medium flow to flow alternately to the left and right of the sensor. This causes an oscillation. The frequency is directly related to the flow rate. The electronics in the measuring cell converts this frequency into an electronic output signal.

This very low pre-pressure requirement makes the DOG very suitable for use in biogas systems. This measuring principle is very cost-effective compared to other measuring principles. The DOG is insensitive to pollution thanks to the large channels. There are no moving parts in the medium so that wear is kept to a minimum.