Following is a definition of terms frequently used in the instrumentation, industrial automation and test & measurement communities.
Vacuum: Any pressure less than atmospheric pressure.
Velocity: The time rate of change of displacement; dx/dt.
Vibration Error Band: The error recorded in output of a transducer when subjected to a given set of amplitudes and frequencies.
Vibration Error: The maximum change in output of a transducer when a specific amplitude and range of frequencies are applied to a specific axis at room temperature.
Viscosity: The inherent resistance of a substance to flow.
Volt: The (electrical) potential difference between two points in a circuit. The fundamental unit is derived as work per unit charge-(V = W/Q). One volt is the potential difference required to move one coulomb of charge between two points in a circuit while using one joule of energy.
Voltage: An electrical potential which can be measured in volts.
Voltmeter: An instrument used to measure voltage.
Volume Flow Rate: Calculated using the area of the full closed conduit and the average fluid velocity in the form, Q = V x A, to arrive at the total volume quantity of flow. Q = volumetric flowrate, V = average fluid velocity, and A = cross sectional area of the pipe.