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results in long-term monitoring, allow the unit to settle for a period of one (1) hour in the gas
composition being monitored prior to use.
6
OPTIMUM UNIT PERFORMANCE
For maximizing the performance of the sensor, the following steps are recommended.
Verify that all electrical connections and made as recommended. Switching the polarity can cause damage
to the unit. Ensure that the DC power supply utilized is appropriate and does not have large peak-to-peak
noise.
Perform a Field calibration after the installation and conditioning steps described in the Start-up section are
completed. DO NOT use 0% H2 as the lower calibration gas. Instead use hydrogen concentration that is
slightly lower than the expected lowest hydrogen concentration (for e.g. if 1% is the expected lowest H2
concentration, then use 0.5% H2 as the lower calibration gas.
For the second calibration gas use a concentration that is slightly higher than the expected maximum H2
concentration.
If the analyzer gets exposed to extended periods of H2, condition the sensor as described in the Start-up
section and follow-up with a Field calibration, if needed.
6.1
PRESSURE EFFECTS
The analyzer is hydrogen specific and sensitive to only the hydrogen partial pressure in the air.
Since changes in total gas pressure will affect the hydrogen partial pressure, they will also affect the
sensor readings. For instance, at one atmosphere pressure, a 2% H2 concentration will be reported
as 2% from the unit. At .9 atm, the reading will decrease to 1.8%.
Normal atmospheric pressure fluctuations may also manifest as small hydrogen changes.
At the factory, the units are typically calibrated at one atmosphere pressure.
Performing the field calibration will compensate for altitude induced inaccuracy.
7
OPERATION
7.1
ANALOG OUTPUT
The following parameters are set at the factory per customer specification at time of order, however
they are user configurable via the serial port.
The user can request for a specific output current or there are analog output ranges the user can
select from, which are listed below. The analog output the user selects is scaled to the user's
hydrogen range of interest. All of this is initially set at the factory per customer specification at the
time of order. Below is the table for standard analog output current ranges:
Current Range
Selection
Standard
Optional
The selected Analog Output Range is scalable from the low to high levels of the hydrogen sensitivity
range. The user can change to another current range of the analog output in the field. Please refer
to the "I" command.
7.2
DISPLAY
The upper row of the LCD indicates a numerical value for the percent hydrogen concentration or
peak hydrogen value. The lower row of the LCD is used to display the hydrogen meter, a
logarithmic bar graph ranging from 0.001% (10 ppm) to 100% hydrogen by volume. An open box on
90000012 R8
HY-ALERTA™ 1600, Intrinsically Safe Area Hydrogen Monitor
Analog Output
Power-On Self
Range
Diagnostic Output
4 mA to 20 mA
0 mA to 20 mA
Error Output
22 mA
0 mA
20 mA
Page 10 of 31
OPERATING MANUAL
3 mA
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