SSi Manual 4559
Page 20 of 26
3-Gas Analyzer PGA3500
Revision Level - D
Zero Calibration – Menu Page 18
This page is used to zero the IR cells. It is
very important to be sure that the sample
gas is a good zero especially for CO2.
Ambient air has nominal percentage of
CO2, which should not be present when
performing a zero calibration. It is
recommended that 99.9% pure nitrogen
be used for zeroing the PGA3500. If there
is no nitrogen present, the CO2 Scrubber
(P/N 13112) can be used to remove the
CO2 from ambient air. The sample gas flow rate should be between 1 and 1.5 SCFH.
When viewing this screen, the current measured values are shown at the left under the
heading
Actual
, while the desired values will be in the center column,
Zero Gas
. The final
column is
Status
, and this shows the percentage difference between the actual and desired
values, followed by a comment. This comment can either be OK, ?OK, or BAD, depending
on how far apart the values are. If the difference is between 0 and 10% of the span value,
then it will be OK and the calibration will proceed without interruption. If the difference is
between 10% and 20%, it will be ?OK, and a warning message will be displayed. Pressing
Enter will allow the calibration to continue. If the value is more than 20% out, it will be
BAD and the calibration will not be allowed to proceed. If this occurs, check to make sure
that you are using the correct gas and that there is adequate flow. If it is still not operating
properly contact SSi for additional support.
It is possible to calibrate one, two, or all three sensors. The default setting is to calibrate all
three, however if you do not want to calibrate one of the sensors you can use the up and
down arrows to access the sensor that you do not want to calibrate, and press Enter over
the existing Yes. This will change it to No, and that sensor will not be calibrated.
To proceed with the calibration of one or more sensors, use the arrow key to move to the
Start button and press Enter. Timers will count down approximately two minutes and at the
conclusion the sensors will be calibrated.
WARNING: Do not pressurize PGA3500 w ith compressed gas. Alw ays start the
flow of Nitrogen and regulate prior to connecting to PGA3500 inlet.
O2 Cell Calibration – Menu Page 19
O2 Cell Calibration is used to calibrate
the oxygen sensor. The oxygen sensor is
calibrated using air (20.9% O
2
) as the
reference. If the oxygen cell output is
outside of a 30% band then the message
REPLACE O
2
CELL! will appear near the
bottom of the screen. When calibrating
the O
2
sensor, no special gas is required,
only fresh ambient air. It is better to
perform this calibration in an office or