API MODEL 200A NO/NO2/NOX – NITROGEN OXIDES ANALYZER
MULTI-POINT CALIBRATION
The method of performing the Multi-point Calibration of the Model 200A NOX Analyzer is using the Dasibi Model 5008 Multi-Gas Calibrator at selected ten concentration points. A super blend gas cylinder diluted to an NIST-traceable NO concentration is manufactured by Scott-Marrin. The recorder data is either ESC 8816 or ESC 8800 Data Logger. The calibration spreadsheet for data record is provided in the network drives P:\airmon\forms\airmon.for\mc-noxca.
The Multi-point Calibration is regularly schedule every three months or after instrument repairs and any conditions that would affect the calibration and the performance of operation.
Prior to calibration of API NOX analyzer, review the status of all TEST values from front panel display that should be within the nominal operation ranges. If any of these values are not within ranges or any fault conditions has to be corrected before proceeding the calibration.
The instruction refers to a designated section on particular performance problems through the course of the procedure.
Not to be confused between the term PPB and PPM concentration units of this procedure. The API analyzers are setup to gas range units in PPB. The Multi-Gas Calibrators and 8800/8816 Data Loggers are configured to gas level units in PPM. The difference value between concentration units is place 3 decimals to the left for PPB to change the concentration units as PPM as it displayed on data logger. Practically this may all be setup in PPM.
1. Disable channel 5,6 and 7 (NO-NO2-NOX) in the data logger if this is at field site.
2. The analyzer should be operating several hours (preferably overnight) before calibration so it is fully warmed up and operation has stabilized.
3. Unplug the sample pump temporarily to replace the in-line filter with a new filter. If the unit has a flow valve on exhaust port, close the valve to replace the filter.
Perform Analog Output test
4. Verify the analyzer NO/NO2/NOX display output voltage matches the voltage input of the data logger (DAS) NO/NO2/NOX readings.
a) The Analog Output test outputs a step voltage pattern and verifies the values of ADC/DAC calibration reflects the measured test channel output voltage.(Data Logger or DVM)
b) DVM (Digital Volt Multimeter) should be use for the test confirming correct voltage output against DAS measurements, preferably 8800 data logger. Make all measurements from analyzer output terminal on back panel.
c) From ESC 8816 logger Home Menu select and enter Real-Time Display Menu/Display Raw Readings. For ESC 8800 press F3 and key in 00 for Repeat Raw 00.
d) Display the Analog Output test on analyzer by pressing button in sequence SETUP-MORE-DIAG-ENTR-NEXT-ENTR.
e) Observe the instrument display 0% and scrolls to 20%, 40%, 60%, 80% and 100%.
f) Observe the ESC 8816 logger channel display NO (A05)= x.xxxx v, NO2 (A06)= x.xxxx, NOX (A07)= x.xxxx. For 8800 logger find SO2 channel, 05 .xxxxD display, 06 .xxxxD, and 07 .xxxxD display. (x as numeric value)
g) Confirm the correct % values on analyzer to logger voltage readings as 0%= 0.000v, 20%= 0.200v, 40%= 0.400v, etc. for 8816 logger and 0%=.0000D, 20%=.2000D, 40%=.4000D etc. for 8800 logger.
h) The analyzer displayed scrolling can be stopped by pressing button below percent display to observe the comparison closely, press percent button again to continue.
i) If the voltages do not match, D/A Calibration has to be performed. Refer to Section 2 I 1-9.
j) Exit back to sample menu on instrument and set the logger back to display Display Readings w/flags for 8816. Press F4 then key in 00 to Repeat Read 00 for 8800 data logger.
Perform Leak Check
4. Disconnect the sample line from sample port if this is at field site.
5. Turn off instrument power switch and disconnect pump power.
6. Remove the top cover of the analyzer.
7. Cap the sample inlet port, remove the DFU filter from ozone generator air inlet at ¼ inch fitting and cap the air inlet.
8. Turn on the instrument, apply pump power and set the TEST function of analyzer to display RCEL.
9. Close the shut-off valve between the pump and the exhaust port.
10. Monitor the RCEL pressure from the point the valve was close to measure reaction cell pressure for 5 minutes. If the pressure changes more than 1 in Hg in 5 minutes, there is a leak. Turn off the instrument power switch, disconnect pump power and tighten all fitting flow lines and seals to prevent the leak. Redo steps 8 to 10 for leak check pressure change in 5 minutes. If the instrument still has a leak, refer to Section A II for Pressure Method Leak Check.
11. If the leak check passed and completed, remove the cap from sample inlet port, from ozone generator air inlet and re-install the DFU filter.
Perform Pressure Check - RCEL Pressure Check and Adjustments
12. Set the TEST function of the analyzer to display SAMP for sample pressure.
13. Obtain an ambient pressure either from monitoring site (channel 10) or call the local weather station for current uncorrected barometric pressure (602) 379-4630. If you call National Weather, please identify yourself your with Air Quality. For shop bench, use either the bench digital Temperature/Pressure gauge or Laboratory Barometer instrument. The laboratory barometer should be converted to uncorrected pressure by subtracting 1.18 of the current measurement during the summer season and subtract 1.175 from correct pressure during the winter season.
14. Disconnect the power from the pump or close the shut-off valve.
15. Allow the pressure reading to stabilize and verify the SAMP display match the obtained ambient pressure. If not, adjust R1 trimpot on Flow/Pressure Sensor board to the obtained ambient pressure.
16. Prior to performing these adjustments check and make necessary corrective action on the performance of pressure and flow systems like: clean inlet filter, orifices and orifice screen filters not plugged up, tighten the flow fittings, and pump is producing enough vacuum.
17. The RCEL reaction cell pressure can be checked or adjusted at this moment. Set the TEST function of the analyzer to display RCEL.
18. Verify the RCEL display match the obtained ambient pressure. If not, adjust R2 trimpot on Flow/Pressure Sensor board to the obtained ambient pressure.
19. Apply power back to the pump or open the shut-off valve.
20. The RCEL nominal operating ranges are 4 to 10 in Hg.
Perform Ozone Flow Check and Adjustment
21. Set the TEST function of the analyzer to display OZONE FL. The OZONE FL nominal operating ranges are 65 to 95 cc/m.
22. If the flow are out of acceptable range, it should be adjusted. Enter the selected function by pressing button in sequence on analyzer SETUP-MORE-DIAG-ENTR-find SIGNAL I/O and ENTR-JUMP-key in 32 then ENTR.
23. The display features “32) OZONE FLOW=xxxx.x MV.
24. Make adjustments on R3 trimpot of Pressure/Sensor board on analyzer to read 2000.0 MV. The reading sets to approximate flow value.
25. EXIT back to sample menu and display the OZONE FL. The flow reading should be between 65 to 95 cc/m.
Perform Sample Flow Check and Adjustment
26. Set the TEST function of the analyzer to display SAMP FLW. The nominal operating flow ranges are 420 to 580 cc/m.
27. If the sample flows are not within the acceptable range, perform sample flow check and adjustment using a mass flowmeter.
28. Connect the Flowmeter (BIOS) to the analyzer sample inlet. The flow correction for standard temperature and pressure is not required. Obtain the Vavg average reading if using BIOS DC-2 flowmeter.
29. Observe the BIOS flow measurement then obtain the 20th average reading and record the flow reading from analyzer. Subtract the analyzer SAMP FLW reading from the BIOS flow value. This result value will be edited in sample flow setting.
30. Display the sample flow adjustment by pressing button in sequence SETUP-MORE-VARS-ENTR-JUMP-key in 4-then ENTR.
31. The display features “4) SFLOW_SET=xxxx CCM”.
32. Press EDIT, then add or subtract the result value from step 29 to the reading shown and key in the new value and press ENTR. The analyzer sample flow updates to the new value.
33. Press ENTR twice for low flow and high flow settings to check the new value does not exceed the warning limits.
34. Press EXIT returns to sample menu and display SAMP FLW to verify flows now match the BIOS average reading.
Calibration
Before starting the Multi-point calibration carefully check the analyzer’s condition such as slope and offset values to ensure if Factory Calibration is recommended if they are not in acceptable range are during the course of the calibration unable to zero or span the instrument. Refer to Section A III Factory Calibration (PMT Calibration).
Verify the instruments NO OFFS and NOX OFFS are within –10 to 150 nominal range, and NO SLOPE and NOX SLOPE are within .700 to 1.300 nominal range. If the slope and offset values are outside of the acceptable range, instrument Factory Calibration has to be performed.
35. Connect a calibration gas line to sample inlet. Note that the line should have a T-connection with at least three feet vent line.
36. For shop bench calibration, connect the calibration line from the 5008 to a T-connection and to sample inlet. Other end of T-connection should be approximate three feet vent line to avoid pressurize the unit.
37. From the Main Menu of 5008 Multi-Gas Calibrator, begin zero air flow by entering CONTROL/SELECT LEVEL (2,1).
38. Enter the level assigned to zero air (00), then ENT.
39. The display will ask, “Are You Sure?” Press up arrow to enter “y”, then ENT.
40. Observe the 5008 display for flow. Usually zero air flow of 10.0 LPM.
41. Press CAL button on the analyzer front panel. Cal LED should be blinking and the display menu changes to <TST TST>, ZERO, CONC and EXIT.
42. If the ZERO is not displayed, the reading is too far out of adjustment to do a reliable calibration. This result should be corrected before continuing the calibration.
43. While the instrument is stabilizing to a designate setting zero, record the appropriate information about the calibration on NO/NO2/NOX Calibration spreadsheet date, location, serial no., etc.
44. Allow the analyzer to sample zero air until it stabilizes when NOX STB reaches 0.2 PPM to initiate for zero calibration.
45. After stable reading has been obtained press ZERO and ENTR. The analyzer is now zeroed the NO and NOX values.
46. Check the analyzer NO OFFS and NOX OFFS to ensure they are still in acceptable range after zero adjustment.
47. If the DAS zero values is acceptable, record the analyzer NO/NO2/NOX display values and DAS NO/NO2/NOX values to NO/NO2/NOX Calibration spreadsheet.
48. The obtainable DAS value is +/- 0.5 ppm.
49. Press EXIT button on analyzer to complete zero adjustment and returns to instrument sample mode.
50. Enter SELECT LEVEL (1) on 5008. Press (21, ENT) to select .400-ppm NO concentration.
51. Press (Up Arrow, ENT) to change “n” to “y” to initialize .400 ppm NO gas flow.
52. Be certain and verify the actual gas concentration being produced from 5008 Multi-Gas Calibrator. This concentration value will be entered in the analyzer at step 54b-c) and step 57 of calibration spreadsheet under INPUT (PPM). Important factors because expected .400 ppm gas selected may not producing exact concentration. Use the produced gas value generated from 5008 menu.
53. Press CAL button on the analyzer front panel. Cal LED should be blinking and the display menu changes to <TST TST>, SPAN, CONC and EXIT.
54. Enter the span gas value of 400-ppb gas in the analyzer to set and store NO/NOX values. Span calibration at 80% full scale.
a) Press CONC button on front panel changes to CONCENTRATION MENU of NOX, NO, CONV, EXIT.
b) Press NO button and enter the value 00399.0, then press ENTR.
c) On Concentration Menu, press NOX button and enter the value 00400.0, then press ENTR
d) Press EXIT button routes back to first calibration menu.
56. Allow the analyzer 400-ppb to stabilize 15 to 25 minutes or using the analyzer <TST> button (stability) NOX STB reading reaches 0.4 PPB and than initiate for calibration.
57. If the span button is not displayed, the span is too far out of adjustment to do a reliable calibration. This result should be corrected before continuing the calibration.
55. After the stable reading has been obtained press SPAN and ENTR. The analyzer is now calibrated the NO and NOX at 400 ppm.
56. Check the analyzer NO SLOPE and NOX SLOPE to ensure they are still in acceptable range after span adjustment.
57. If the DAS span value 400 ppm is acceptable, record the analyzer NO/NO2/NOX display values and DAS NO/NO2/NOX values to NO/NO2/NOX Calibration spreadsheet.
58. The obtainable DAS value is +/- 0.5 ppm.
59. Press EXIT button on analyzer to complete span adjustment and returns to instrument sample mode.
60. Enter SELECT LEVEL (1) on 5008. Enter the level assigned for NO concentration of .450 ppm (10), then ENT.
61. Observe for actual NO concentration being produced to record at step 63-calibration spreadsheet under INPUT (ppm) NOX.