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Instrument Maintenance Model T101 Instruction Manual
206
8.3.5. MAINTAINING THE H
2
S SO
2
CONVERTER
The catalyst contained in the H
2
S SO
2
converter of your T101 must be replaced
periodically in order for the analyzer to continue measuring H2S accurately and
reliability.
This material is capable of efficiently converting H
2
S into SO
2
for up to 6000
ppm/hours. This means that if the H
2
S content of the sample gas is typically around 600
ppb, the scrubber will function for approximately 10 000 hours, a little over 13 months.
If, however, the typical ambient H
2
S level of the sample gas is 1000 ppb, the scrubber
would only last for approximately 6000 hours or about 8 months.
8.3.5.1. Predicting When the Converter Catalyst Should Be Replaced.
To determine how long the H
2
S SO
2
converter will operate efficiently:
1. Measure the amount of H
2
S in the sample gas.
2. Divide 6000 by the H
2
S concentration.
EXAMPLE: If the H
2
S concentration is 750 ppb:
Operational hours= 6000 ppm/hr ÷ 0.75 ppm
Operational hours= 6,00,000 ppb/hr ÷ 750 ppb
Operational hours= 8000 hrs
8.3.5.2. Checking the Efficiency of the H
2
S SO
2
Converter
To check to see if your H
2
S SO
2
converter is operating properly:
1. Set the analyzer to SO
2
measurement mode (see Section 4.5.1).
2. Supply a gas with a known concentration of SO
2
to the sample gas inlet
of the analyzer.
3. Wait until the analyzer’s SO
2
concentration measurement stabilizes. This
can be determined by setting the analyzer’s display to show the SO2
STB test function (see Section 4.2.1) SO2
S
TB should be 0.5 ppb or
less before proceeding.
4. Record the stable SO
2
concentration
5. Set the analyzer to H
2
S measurement mode (see Section 4.5.1).
6. Supply a gas with a known concentration of H
2
S, equal to that of the SO
2
gas used in steps 2-4 above, to the sample gas inlet of the analyzer.
7. Wait until the analyzer’s SO
2
concentration measurement stabilizes. This
can be determined by setting the analyzer’s display to show the H2S
STB test function (see Section 4.2.1) H
2S STB should be
0.5 ppb or
less before proceeding.
8. Record the stable H
2
S concentration
9. Divide the H
2
S concentration by the SO
2
concentration
EXAMPLE: If the SO
2
and H
2
S concentration of the two test gases used is
500 ppb:
Measured SO
2
concentration = 499.1 ppb
Measured H
2
S concentration = 490.3 ppb
07266B DCN6485