Gas Analysis with the Mass Flowmeter

The FMA-4100/4300 series mass flow totalizers and meters can be programmed remotely using the RS232 or RS485, functioning to measure the rate of gas flow and record it in 23 selectable units. These devices have a multitude of applications due to an extensive list of functions, including high and low gas flow alarms, gas flow totalizers, automatic zero adjustments, 2s relay outputs, jumper selectable 0 to 5 Vdc or 4 to 20 mA analogous outputs, status LED diagnostics, storable calibrations and internal or user-specific K-factors. The local LCD display has 2 lines, each of 16 characters and modifiable back lighting, which enables concurrent readings. Use of RS232 or RS485 enables access of further data, such as the temperature of CPU, auto zero, flow, linearization table adjustment, settings for both totalizer and alarms, gas table, conversion factors, selection of units and dynamic response compensation.

Both the local and remote activation of the FMA-4100 or 4300 enables automatic offset zero adjustment. This is particularly useful in situations where there is minimal flow through the meter when it is being modified. Digital commands enable the current automatic zero value to be read, saved or started. Totalizer settings can be altered in order to enable various functions: assigning action to a pre-set value, setting to zero, starting at a pre-set flow, starting/stopping totalizing and reading. Alarms can also be set up prior to use which can indicate both high and low flow, and can be appointed pre-set delay intervals of 0 to 3600 seconds, which activate the contact closer. An additional feature, called the latch mode control, functions to permits each relay to be latched on or ensure the interrelated alarm status. However, these transducers cannot be used to measure oxygen.


  • Calibrations: Performed at standard conditions [101.4 kPa (14.7 psia) and 21.1 °C (70 °F)] unless otherwise requested or stated
  • Environmental (PER IEC 664): Installation Level II; Pollution Degree II
  • Flow Accuracy (Including Linearity): ±1% of FS at calibration temperature and pressure
  • Repeatability: ±0.15% of full scale
  • Flow Temperature Coefficient: 0.15% of full scale/°C or better
  • Flow Pressure Coefficient: 0.01% of full scale/psi (6.895 kPa) or better
  • Turndown Ratio: 50:1
  • Flow Response Time: 600 ms time constant; approximately 2 seconds to within ±2% of set flow rate for 25 to 100% of full scale flow
  • Max Gas Pressure: 3447 kPa gauge (500 psig)
  • Max Pressure Drop: Max Flow ≤ 10 SLM: 1.28 kPa (0.18 psi)
                                        Max Flow > 10 SLM: 27.58 kPa (4 psi)
  • Gas and Ambient Temperature: 5 to 50 °C (41 to 122 °F)
  • Relative Gas Humidity: Up to 70%
  • Leak Integrity: 1 x 10-9 SCCS He max to the outside environment
  • Attitude Sensitivity: Deviation of up to 1% from stated accuracy, after re-zeroing
  • Output Signals: Linear 0 to 5 Vdc (3000 Ω min load impedance); Linear 4 to 20 mA (500 Ω max loop resistance). Max noise 20 mV peak to peak (for 0 to 5 Vdc output)
  • Relay: SPDT (30 Vdc, 1A)
  • Transducer Input Power: 11 to 26 Vdc, 100 mV max peak to peak output noise
  • Power Consumption: +12 Vdc (200 mA max); +24 Vdc (100 mA max); Circuit board has built-in polarity reversal protection, 300 mA resettable fuse provide power input protection
  • Wetted Materials:
    •     Standard Aluminum Models: Anodized aluminum, brass, 316 stainless steel, FKM O-rings
    •     Optional Stainless Steel Models: 316 stainless steel, FKM O-rings
    •     Optional O-ring Materials: Buna, EPR (Ethylene Propylene), or perfluoroelastomer
  • Inlet and Outlet Connections:
    •     Model FMA-4100/4300: Standard 6.35 mm (1/4") compression fittings for up to 50 SLM.
                                                    Standard 9.53 mm (3/8") for models above 60 SLM
    •     Optional: 3.18 or 9.53 mm (1/8" or 3/8") compression fittings
  • Display (FMA-4300 Models): Local 2 lines x 16 characters LCD with adjustable backlight (2-lines of text)
  • Calibration Options: Standard is one 10-point NIST traceable calibration. Optional, up to 9 additional calibrations may be ordered at additional charge. Contact OMEGA for additional information
  • CE Compliance: EMC compliance with 89/336/EEC as amended
    •     Emission Standard: EN 55011:1991, Group 1
    •     Class A Immunity Standard:
    •     EN 55082-1:1992

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