Span Calibration – Menu Page 24

 

This page is used to span calibrate the IR cells. It is very important to be sure that a Certified Primary Standard sample gas within the noted specifications is used. The nominal composition of this gas should be:

 

20% CO (Carbon Monoxide)

0.5% CO2 (Carbon Dioxide)

5% CH4 (Methane or Natural Gas)

40% H2 (Hydrogen)

Balance N2 (Nitrogen)

 

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, Span 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.

 

To proceed with the calibration of one or more sensors, use the up and down arrows and the numeric keypad to enter the specific values of each gas. These will be listed on the calibration cylinder. 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.

 

When this data has been entered, 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 with compressed gas.  Always start the flow of Nitrogen and regulate prior to connecting to PGA3500 inlet.