Routine Operation - Emerson ROSEMOUNT NGA2000 HFID Instruction Manual

Model NGA2000 HFID
If the user is unable to calibrate the Analyzer
Module (i.e., when ZERO or SPAN is initiated,
nothing happens), several possible solutions
present themselves. One solution relates to
the use of an incorrect gas for zeroing or
spanning (e.g., using a high concentration gas
to zero or a zero gas to span the Analyzer
Module). Simply recalibrating with the appro-
priate gas(es) will not correct the problem be-
cause the ZERO OFFSET or SPAN FACTOR
has been set to an extreme value in the proc-
ess.
To remedy the problem, do the following:
1. Verify that correct zero and span cali-
bration gases are being used properly. If
so, attempt to recalibrate according to
instructions at the beginning of Section
3-4 on page 3-4, ensuring that the oven,
sample and case temperatures and dis-
played measurement reading are stable
before initiating the calibration routine. If
incorrect gases were used in the initial,
failed calibration, skip to Step 2.
2. Make the following selections from the
Main Menu: Expert Controls and Setup,
Analyzer Module Setup, then Calibration
Parameters. Disable Calibration Ad-
justment Limits.
3. Recalibrate the analyzer module accord-
ing to instructions at the beginning of
section 3-4 on page 3-4, ensuring that
oven, sample, and case temperatures
and displayed measurement reading are
stable before initiating the calibration
routine.
4. Enable Calibration Adjustment Limits in
the Calibration Parameters menu.
If the range selections straddle 725 ppm,
CH , the zero and span calibration for each
4
range must be done separately.
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ROUTINE OPERATION

After case, oven, and sample temperature
stabilization, calibration, and binding, proceed
as follows:
Rosemount Analytical Inc. A Division of Emerson Process Management
Note
Instruction Manual
Supply heated sample gas to SAMPLE
INLET. Adjust external flow controller or throt-
tle valve so that the sample inlet pressure is
between 5 and 9 psig, 7 psig nominal. The
reading on the SAMPLE pressure gauge and
sample and oven temperatures should be the
same as that used during adjustment of the
zero and span calibration gas control.
Adjust the Range Number setting. The Ana-
lyzer Module will now automatically and con-
tinuously output the measured hydrocarbon
content of the sample. Output is in terms of
the particular hydrocarbon present in the span
gas. Note that readings obtained during op-
eration depend on the concentration of total
hydrocarbons in the sample.
If maximum sensitivity is required from the
HFID Analyzer Module, use an optimum com-
bination of settings on the FUEL, and AIR
pressure regulators. Settings must be deter-
mined experimentally, but the curves in Figure
3-1 on page 3-7 and Figure 3-2 on page 3-7
may be used as guides.
The Analyzer Module will not allow the user to
increase the upper limit of a range beyond the
"maximum range" software setting. To change
the "maximum range" value, select the follow-
ing from the Main Menu: Technical Configura-
tion Menu, Service Menus, Manufacturing
Data, and Analyzer Module Data. Select
Maximum Range, and use the arrow keys to
scroll the indicated value. The same applies
for Minimum Range settings.
During shutdown, always turn off fuel gas first,
then the air and sample gases. The flame can
also be turned off by setting Ignition System
Enable to "Off" in the Light Flame menu (un-
der Basic Controls). Subsequently, remember
to set Ignition System Enable to "On" before
attempting to ignite the flame.
After initial startup, or startup following a pro-
longed shutdown, the Analyzer Module re-
quires about one day's continuous operation
to stabilize. For several days afterwards, cali-
brate daily. The frequency of subsequent cali-
brations can be reduced as experience
dictates, consistent with the accuracy re-
quirements of the particular application.
Startup and Operation
748297-E
June 2003
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