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Instruction Manual
HAS60E-IM-HW
June 2007
NGA 2000 CLD
3 - 15OperationEmerson Process Management GmbH & Co.OHG
(b-a)
(c-d)
(80-85)
(80-20)
12. Close valve MV1. The NO concentration should
be equal to or greater than the reading in Step 7.
This indicates whether the NO contains any NO
2
.
13. Calculate the efficiency of the NO converter by sub-
stituting the concentrations obtained during the test
in the equation below:
%efficiency = 1 + x 100
Where:
a = recorded concentration in Step 10
b = recorded concentration in Step 11
c = recorded concentration in Step 8
d = recorded concentration in Step 9
In the example in figure 3-23 the following calcula-
tions would apply:
%efficiency = 1 + x 100 = 92%
Efficiency checks should be made on each ana-
lyzer range, using an NO span gas concentration
appropriate to the instrument range.
NOTE
In the initial measurement, after lowering the tem-
perature setpoint in Step 2, the efficiency will nor-
mally be less than 92 %
14. Reset converter temperature setpoint 20 °C higher,
wait 15 minutes for temperature equilibration, and
measure conversion efficiency by repeating Steps
3 through 13.
Conversion efficiency should be improved.
15. Repeat Step 14 until:
a) 95 % to 98 % efficiency is attained or
b) the final 20 °C converter temperature adjust-
ment yields an increase in efficiency of less than
1 %.
16. Reset converter temperature setpoint 5 °C lower.
Converter temperature is now set to the front edge
of the plateau on the efficiency-vs.-temperature
curve (see figure 3-23). This setting should pro-
vide the optimum combination of high conversion
efficiency and low ammonia interference.
17. Wait 15 minutes for temperature equilibration, and
check converter temperature. Compare present
temperature with original value. Normally, converter
temperature should be in the range of 300 °C
to 400 °C (572 °F to 752 °F).
c. Subnormal Conversion Efficiency
If measured conversion efficiency of between 95 % and
98 % is unobtainable within the normal temperature
range, the most probable cause is depletion of the cata-
lytic material within the converter.
However, before concluding that the converter is defec-
tive, ensure that the conversion efficiency measurement
is accurate. Though the measured efficiency is less than
the 95 % to 98 % range, the actual efficiency may be
somewhat higher.
An apparent subnormal efficiency can be due to a prob-
lem external to the Analyzer Module, perhaps located
either within the test setup or between it and the Ana-
lyzer Module. Check the following:
1. Leakage
2. Loss of NO
2
between test setup and Analyzer
Module. Such loss can occur by reaction with a
rubber diaphragm in a pressure reagulator or flow
controller. Stainless steel diaphragms are pre-
ferred. Loss can also occur during passage through
filter media.