As a result of the twist, the sine waves generated by the pickoffs are now out of phase with each other because the inlet side is lagging behind the outlet side. The amount of time difference between the sine waves is measured in microseconds and is called Delta-T. Delta-T is directly proportional to the mass flow rate so that the greater the mass flow rate results in greater Delta-T.

With Micro Motion MVD™ digital signal processing, time delay is measured 2400 times faster enabling Delta T to be measured with faster response, less noise, and additional diagnostics.

Delta-T is a function of both the phase difference and the frequency of the sine wave signals.

Micro Motion straight tube flowmeters measure density in the same way as curved tube flowmeters (see section on Density operating principle). It is, therefore, possible to measure volume flow in the same way by dividing the measured mass flow rate by the simultaneous density measurement.