These digital flowmeters represent a new generation in mass flow technology. Meters incorporate a precision microcontroller and nonvolatile memory that stores all hardware specific variables, up to 10 different calibration tables, conversion factors for up to 32 gases, and supports up to 23 volumetric flow or mass flow engineering units, including user defined units. This feature allows the same meter to be calibrated for multiple gases while maintaining the rated accuracy on each. In addition, provision is made for a user-defined conversion factor. Conversion factors may be applied to any of the ten gas calibrations via digital interface commands. Program flowmeters remotely via RS-485 or RS-232. Each unit comes with a 15-pin D-connector with a stripped 6-ft, 3-wire computer communications cable and a 3-ft, 2-wire cable for connection to a power supply. Additional cables as well as power supplies for the flowmeters are available below.
Flowmeters support various functions including programmable flow totalizer, high and low flow alarm, automatic zero adjustment, two relay outputs, jumper selectable 0 to 5 VDC or 4 to 20 mA analog outputs, status LED diagnostic, and internal or user-specific K-factors. LCD display with adjustable back light provides flow, total, and diagnostic reading simultaneously. The digital RS485 and RS232 interfaces provides access to applicable internal data including flow, CPU temperature, auto zero, totalizer and alarms settings, gas table, conversion factors and engineering units selection, dynamic response compensation and linearization table adjustment. The analog interface provides 0 to 5 VDC or 4 to 20 mA outputs for flow reading. The auto zero feature necessitates a condition of absolutely no flow through the meter during the adjustment process. Provisions are made to either start, read, or save the current auto zero value via digital commands.
The total volume of the gas is calculated by integrating the actual gas flow rate as a function of time. Program high and low gas flow alarm limits via digital interface. Alarm action can be assigned with preset delay interval (0 to 3600 seconds) to activate the contact closure (separate for high and low alarm). Latch mode control feature allows each relay to be latched on or follow the corresponding alarm status.
Lower-cost units are also available without LCD for OEM applications in cooling systems, semiconductor manufacturing, or gas chromatography applications. Meters with Profibus industrial communication capabilities are also available. Contact an Applications Specialist for additional information regarding these options.
Please note that these mass flowmeters are designed to work only with clean gases. Never try to measure flow rates of liquids with these meters.