The majority of all gas measurement used in the
world today is performed by two basic types of
meters, positive displacement and inferential.
Positive displacement meters, consisting mainly of
diaphragm and rotary style devices, generally
account for lower volume measurement. Orifice,
ultrasonic and turbine meters are the three main
inferential class meters used for large volume
measurement today. Turbines are typically
considered to be a repeatable device used for
accurate measurement over large and varying
pressures and flow rates. They are found in a wide
array of elevated pressure applications ranging
from atmospheric conditions to 1440 psig.
Turbine meters have also become established as
master or reference meters used in secondary
calibration systems such as transfer provers. A
significant number of both mechanical and
electrical outputs and configurations have become
available over the past 60 years of production.