The Model AFC mass flow controllers are designed to indicate flow rates and control set flow rates of gases. Each of these units incorporates an advanced straight tube sensor in conjunction with flow passage elements constructed of stainless steel. LED readouts of command modules are supplied with 0 to 100 percent calibrations. Zero and span adjustments are conviently accessible from outside of the transmitters. The controllers include an electromagnetic control valve that allows the flow to be set to any desired flow rate within the range of the particular model. The valve is normally closed as a safety feature to ensure that gas flow is shut off in case of a power outage.