Electronic Flow Sensing
Electronic flow sensor (EFS) calibration
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Electronic flow sensor (EFS) calibration
Electronic flow sensor (EFS) calibration may be performed any time to
ensure displayed flow rate accurately represents real gas flow rate
through the sensor. The EFS is factory•calibratedfor four standard
gases, H
, He, N , and Ar/CH , within the flow rate range of 0 to 100
ml/min. This covers the majority of chromatographic applications.
Two situations where it would be appropriate to perform recalibration
would be where a nonstandard gas is to be used (e.g., something other
than H
, He, N , or Ar/CH ), or if flow rates in excess of 100 ml/min are
to be used.
EFS calibration requires setting two values for a given flow
channel•first, the zero value (defined with no flow through the given
flow channel) and then the gain value (calculated, based upon a
measured flow rate value).
If calibration is being performed for H
2
, observe proper safety
precautions to prevent fire or explosion hazard.
WARNING
Prior to performing the calibration procedure, the following must be done:
The instrument must be on for at least one hour for thermal
equilibration of the EFS.
Since gas flow through the channel to be calibrated will be
interrupted, detectors should be turned off (particularly an NPD or
TCD! ), and the oven cooled to ambient temperature (to protect
columns).
A flow•measuringdevice is required, accurate to better than 1 ml/min.
The EFS is calibrated to measure volumetric flow at standard
temperature and pressure. Flows measured at ambient temperature
with a bubble flow meter will have to be converted from ambient
temperature and pressure to standard temperature and pressure.
