Mass Flow - Analog

HFM-301 Mass Flow Meter

HFM-301 Mass Flow Meter

Model HFM-301 can measure flow ranges from 0-25 up to 0-1000 slm (Air Equivalent); uses elastomer seals, provide analog outputs, and are constructed of stainless steel. The controller (HFC-303) has a normally closed valve. Corrosive gases, with the exception of the halogens, pressures up to 1000 psig (optional) are easily measured.

The THI Mass Flow 300 Series meters and controllers are designed to accurately measure mass flow without corrections or compensations for gas pressure and temperature. They are accurate to better than ±1.0% of full-scale. THI mass flow instruments do not require any periodic maintenance under normal operating conditions with clean gases. No damage will occur from the use of moderate overpressures (~500 psi) or overflows. Instruments are normally calibrated with the appropriate standard calibration gas (nitrogen), then a gas conversion factor (GCF) is used to adjust the output for the intended gas. Special calibrations for other gases, such as oxygen, helium and argon, are available upon special order.

These products contain a number of features that set them apart from other available instruments: (1) They are inherently linear; no linearization circuitry is employed. Should recalibration in the field be desired (a calibration standard is required), the customer needs to simply set the zero and span points. (2) The output signal is linear for very large overflows and will not come back on scale when a flow an order of magnitude over the full scale flow rate is measured. (3) The instrument incorporates a removable/replaceable sensor module. (4) ) The unit has very fast settling times.


  • Accuracy ±1.0% of Full Scale
  • Settling Times:
    • HFM-301 ≤ 0.4 sec
    • HFC-303 ≤ 2.0 sec
  • Available Flow Ranges:
    • 0-25 up to 0-1000 slm (Air Equivalent)
  • Operating Pressures to 500 psi or higher
  • NIST Traceable Calibration


• Leak Testing
• Research
• Vapor Deposition
• R&D and Process Flows
• Semiconductor Processes
• Pollution Monitoring
• Gas Blending
• Chromatography