Process variable measurement using primary element connection platform

An apparatus for measuring a process variable of a process fluid based upon a process variable sensor measurement, includes an elongate spool that provides a spool conduit therethrough adapted to be coupled in line with process piping to receive a flow of process fluid. A meter body is carried in the elongate spool and receives the spool conduit therethrough. The meter body has a primary element opening which extends from the spool conduit to outside of the meter body. A carrier is configured to removably mount to the meter body and includes a primary element in the spool conduit through the primary element opening. A process variable transmitter is coupled to the primary element and is configured to measure the process variable of process fluid. The meter body is preferably configured to receive different types of primary elements carried on the carrier.