SO4 Audit and Calibration
Purpose: The SO4 audit and calibration assures that
the SO4 analyzer has the correct gas response.
This can be accomplished by introducing a known quantity of gas to the
inlet and auditing the response on the instrument. The terminology for this type of audit is GRC
(Gas Replacement Calibration). Each GRC
has a RF (Response Factor). This RF
value should be 1.000 +/- 2%.
Required Equipment: Precision flat head
screwdriver
SO4 Analyzer Zero Audit and Calibration
1. Open
the Gas Calibration worksheet.
2.
In Site Manger go to the
Tools tab and select Trigger Cals.
3.
In the Trigger Cals Menu
select SO4 GRC Zero and press Start Calibration.
4.
Under the Tools tab
select Query 1-Minute Data. In the Query
Data Tool Menu select SO4.
5.
Enter the Background
(BKG) number onto the Gas Calibration worksheet in the Zero Audit section. The number should be entered in the As Found
column.
a.
To find the BKG number
on a 43CTL analyzer scroll down to Calibration Factors and press enter. Then scroll to SO2 BKG PPB and press
enter. The top number is the PPB (Parts Per Billion) number for the analyzer and the bottom number
is the BKG number.
6.
Wait 15 minutes until
the SO4 number is stable. Contact
7.
Enter the SO4 data in
the As Found Zero Audit section of the Gas Calibration worksheet. The PPB number should be approximately
1.00. If it isn’t, adjust the BKG or
Zero Pot.
a.
If you have a 43CTL
analyzer it should already be in the adjustment screen (follow step 6). Use the up and down arrows to adjust the
Background number so that the SO2 PPB number is ~1.00. When this is complete press enter on the
analyzer.
8.
Record the final BKG
and/or Zero Pot number in the As Left cell of the Gas Calibration worksheet.
9.
On the Query Data Tool
press Get Data and enter the SO4 number in the As Left cell of the Gas Calibration
worksheet.
10.
Press Run or Auto on the
analyzer and close the Trigger Cals Menu.
SO4 Analyzer Span Audit
11.
This procedure will
obtain the current RF value for the SO4 analyzer.
12.
Open the Gas Calibration
Worksheet and Enter the correct SO2 concentration (found
on the gas cylinder) in the blank provided.
13.
Enter the final SO4 PPB
number from the Zero Audit into the As Found zero of the SO4 Analyzer Response.
14.
On Site Manager go to
the Tools tab and select Trigger Cals.
15.
In the Trigger Cals
menu, select SO4 GRC Point 1 and press Start Calibration.
16.
Under the Tools tab
select Query 1-Minute Data. In the Query
Data Tool menu select Air MFC, Gas MFC and SO4.
17.
Wait 15 minutes until
the data for the SO4 isn’t changing by more than 0.05 PPB per minute. This is so that the instruments can equalize
before going on to the next step.
18.
Press Get Data on the
Query Data Tool. If the query data
numbers are approximately equal to the number on Site Manager then the data is
stable and an average can be taken.
19.
Enter the Air MFC, Gas
MFC and SO4 data in the As Found section of the Gas Calibration worksheet. Also enter the COEF.
a.
To find the COEF
(Coefficient) number on a 43CTL analyzer scroll down to Calibration Factors and
press enter. Then scroll to SO2 COEF and
press enter. The top number is the PPB
(Parts Per Billion) number for the analyzer and the
bottom number is the COEF number.
20.
Go to Trigger Cals and
press Stop Calibration then select SO4 GRC Zero and press Start Calibration.
21.
Wait 13 minutes until
the data for SO4 is stable. Contact
22.
Enter the Air MFC and
SO4 data in the As Found section of the Gas Calibration worksheet.
23.
The Actual Expected
value is calculated by adding the final Zero Value and Calculated Expected
Value.
24.
The RF is now displayed
in the worksheet. If the RF is between
0.98 and 1.02, the calibration audit is complete.
25.
Close the Trigger Cals
window and Query Data window.
26.
Save the Gas calibration
worksheet.
27.
If the RF is not within
the specified range continue with the Analyzer Span Calibration.
SO4 Analyzer Span Calibration
1. This procedure will be used to calibrate the
analyzer and obtain a corrected RF value for the SO4 analyzer.
2.
Using the As Found data
for the SO4 Zero, enter the Air MFC and SO4 values in the As Left section.
3.
On Site Manager go to
the Tools tab and select Trigger Cals.
4.
In the Trigger Cals
menu, select SO4 GRC Point 1 and press Start Calibration.
5.
Under the Tools tab
select Query 1-Minute Data. In the Query
Data Tool menu select Air MFC, Gas MFC and SO4.
6.
Wait 10 minutes for the
data for SO4 is stable.
7.
Adjust the instrument.
a.
On 43CTL analyzers press
menu. Scroll down to CAL FACTORS and
press ENTER. Go to the SO2 COEF and
press enter – Set the SO2 COEF to 1.0.
The PMT can be adjusted by taking the top off of the analyzer. With the top of the analyzer off, look on
the left side of the bulkhead at the front.
There is a blue box with an orange grommet on the top. Inside the grommet is the PMT adjustment screw. Slowly adjust the analyzer until the SO2 ppb
on the analyzer, or SO4 on Site Manager, is approximately equal to the Actual
Expected value from the As Found section.
The PMT adjustment screw on the inside of the analyzer is a coarse
adjustment and the SO2 COEF is a fine adjustment. The SO2 COEF should always be close to a
standard of 1.00 but it can be used to adjust the instrument to a tighter
tolerance. The SO2 COEF will adjust the
instrument in smaller increments than the PMT adjustment. Replace the top of the analyzer.
8.
When the analyzer
adjustments are complete, let the analyzer stabilize for 5 minutes. Press Get Data on the Query Data Tool.
9.
Enter the Air MFC, Gas
MFC and SO4 data in the As Found section of the Gas Calibration worksheet. Also enter the COEF.
10.
The RF is now displayed
in the worksheet. The RF should now be
between 0.98 and 1.02, the calibration is complete. If the RF is not within specification, repeat
the calibration part of the procedure again.
11.
Go to Trigger Cals and
press Stop Calibration then select SO4 GRC Zero and press Start Calibration.
12.
Wait 5 minutes for the
data for SO4 to be stable. Press Get
Data on the query data tool.
13.
Enter the Air MFC and
SO4 data in the As Left section of the Gas Calibration worksheet.
14.
The RF is now displayed
in the worksheet. If the RF is between
0.98 and 1.02, the calibration is complete.
If the RF is not within specification, repeat the calibration part of
the procedure again.
15.
Close the Trigger Cals
window and Query Data window.
Save the Gas calibration worksheet.