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Teledyne API Model 201A NH
3
Analyzer Instruction Manual, 04689, Rev. B1
2.1.3 NH3 Calibration
Since the system efficiency is less than 100%, it is necessary to determine a conversion
efficiency factor for ammonia and enter it into the system.
1. Set the converter efficiency to 1.0000 by:
Press CAL-CONC-CONV-SET on the keyboard
Press the keys under the numbers until 1.0000 appears.
Press EXIT to return to the sample mode.
2. Introduce ammonia span gas of known concentration into the instrument. Allow time for
instrument stabilization. The final readings will be less than the concentration calculated
from flows. For example with 400 ppb NH3 span gas:
TN = 40 ppb
TNx = 380 ppb
The 40 ppb TN reading is due to the fact that the moly converts a small amount of the
NH3 gas to NO. The 380 ppb TNx reading is due to ammonia conversion plus some
conversion of nitrogen and oxygen in the dilution air.
3. Continuing with the example above, the instrument will report a NH3 concentration value of
340 ppb. Divide the reported NH3 concentration by the concentration computed from flow
data.
NH3 converter eff. = [NH3
M201A
] / [NH3
FLOWS
]
From the above example :
M201A NH3 reading = 340 ppb
NH3 conc from flows = 400 ppb
340 / 400 = 0.85 NH3 converter system efficiency
4. This value now is entered into the instrument.
Press CAL-CONC-CONV-SET
Press the buttons under the numbers until the desired value is entered, in this case
0.8500, then press ENTR.
Press EXIT to return to SAMPLE mode.
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