The Series GFM2, GFM3 and GFM4 Gas Mass Flowmeters from Dwyer Instruments, Inc. are ideal for measuring the flow rates of a wide variety of gases. Each series provides a high ±1% FS accuracy and ±0.25% FS repeatability and can store calibration information for up to 10 different flow gases. Digital RS-232 or RS-485 interfaces allow for easy communication and for multi-drop capability of up to 256 units (RS-485 only). This user-friendly interface allows the user to set alarms remotely to alert when high or low flow thresholds being exceeded. Self-diagnostics run at start up and a pressure limit of up to 500 psi (34.5 bar).