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201/203 Series 
Page 4 of 20 
1. General 
Information 
The Hastings HFM-201/HFC-203 series  Mass flow meter (HFM-201) and controller (HFC-203) 
are designed to accurately measure and control mass flow over the range of 30 slm to 500 slm, 
without corrections or compensations for gas pressure and temperature with an accuracy of better 
than ±1% from the mean (±2% FS for 500 slm).  Hastings 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/3.45MPa) or overflows. Instruments are normally 
calibrated with the appropriate standard calibration gas (nitrogen) then a correction factor 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.  
1.1. Features 
•  LINEAR BY DESIGN.  The HFM-201/HFC-203 series is 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.  There will be no appreciable linearity change of the 
instrument when the flowing gas is changed. 
•  MODULAR SENSOR.  The HFM-201/HFC-203 series incorporates a removable/replaceable sensor 
module.  Field repairs to units can be achieved with a minimum of production line downtime.  
•  METER SETTLING TIME.  Changes in flow rate for the HFM-201 are detected in less than 2 seconds 
when using the speed up circuitry. 
•  LOW TEMPERATURE DRIFT.  The temperature coefficient of span for the HFM-201/HFC-203 series 
is typically less than 0.05% of full scale/°C from 15-45°C.  The temperature coefficient of zero is typically 
less than 0.1 % of reading/°C from 0-50°C. 
•  FIELD RANGEABLE.  The HFM-201/HFC-203 series is available in ranges from 30 slm to 500 slm.  For 
HFC-203 controller’s, an orifice change is required as well. Calibration is required after all changes. 
•  CURRENT LOOP.  The 4-20 mA option gives the user the advantages of a current loop  
output to 
minimize environmental noise pickup.