Hach 3654 Portable H2/N2 Analyzer TV Converter Box User Manual


 
40 of 66 Calibrations - 3654 Portable H2/N2 Analyzer
Operator Manual
ORBISPHERE
4.2.4 Calibrating In a Liquid H
2
or N
2
Solution
The sensor can be calibrated in a standard liquid solution that has a known concentration
of H
2
or N
2
. You can create a solution with a known concentration by dissolving H
2
or N
2
in water at a measured temperature and pressure. Alternatively, analyze a carbonated
beverage independently by some acceptable means.
Note:
A flow rate lower that 150 ml/min can be used for the calibration, but you must ensure
that all measurements made after the calibration are made at exactly the same flow rate
as is used for the calibration. To ensure accurate results it is recommended to use a
model 32311 Flow Meter as described in “Model 32311 Flow Meter” on page 41.
If the instrument makes two consecutive measurements with less than 1% difference, it
calibrates against this stabilized value. The LCD then displays the message [CAL] to
indicate calibration has been successfully completed
If the calibration does not complete, the LCD displays the message [Err]. The reason
for this calibration error is either that the measured gas partial pressure is under 5 mbar,
or that a wrong instrument key was pressed during the calibration steps.
1) Set the gas measurement phase to
Dissolved and set the calibration
medium to In a liquid or a gaseous
sample at known concentration (as
detailed in “Calibration Medium” on
page 32).
2) Press the CAL button. Remember, this
button may have been locked out to
prevent an accidental reset (see “Locking
Out the Instrument’s CAL Button” on
page 32 for details).
3) A brief clearing [---] message
appears.
4) Press CAL again within a 3 second
period. The instrument then displays the
concentration of H
2
or N
2
, based on the
last value of the calibration coefficient.
5) Modify this reading using the Up/Down
Arrow keys until the displayed
concentration agrees with that of the
calibration solution.
6) Press CAL again.
7) Start the flow of the standard (calibration)
solution through the flow chamber. Adjust
the flow until the liquid is foam-free. The
flow rate should be a minimum of 150 ml/
min and be stable.