Instruction manual

Instruction Manual
760006-A
September 2001
3-8 Operation Rosemount Analytical Inc. A Division of Emerson Process Management
Model NGA 2000 Platform
3-5 ROUTINE OPERATION
Once an NGA 2000 system has been properly
installed, it will need little attention. The Ana-
lyzer modules will need to be calibrated at in-
tervals, and the sample system will have to be
maintained. Calibration gas information will
have to be entered into the Calibration gas
menus for each Analyzer module whenever
gas bottles are changed.
Calibration information is given both in the
Analyzer modules manuals and in the NGA
2000 Reference manual.
Certain Analyzer modules require periodic
maintenance: CLD Analyzer modules need
new converter material and occasional ozo-
nator replacement; FIDs need their flame
towers cleaned; NDIR Analyzer modules re-
quire periodic sample cell cleaning. See their
appropriate manuals for details.
It is possible to use several means of making
digital communication between the NGA 2000
system and a PC. This communication can be
via AK or Modbus over RS 232 or RS 485, or
directly over the LON. Using any of these the
PC may be setup to control the operation of
the system, and to download calibration in-
formation as desired.
If an NGA 2000 component is changed out,
the Platform and also the PC interface must
be told about it. The simplest way to tell the
Platform is to power it down and back up
again. It will re-interrogate the network and
load the new component into its database. If it
runs out of memory during this operation, it
will hang, and you will have to reset it, and
then rebind everything. See the NGA 2000
Reference manual for details.
A PC LON interface will also have to be reset;
AK and Modbus will have to be re-addressed
also due to the change in the database.
a. Correct Operation
The following is a summary of what you
should expect from an NGA 2000 system.
The response of the screen to user inputs
- such as changing menus or editing vari-
ables –should be immediate, with new
menus appearing well within one second.
The main reading should show stable
numbers on zero or span gas, except at
its lowest range where the 1% of range
noise level may be noticeable. Analyzers
should hold their calibration to at least 1%
of range per day (see their specifications
for details on this).
There may be a perceptible delay in indi-
cation of secondary values, such as flow
and pressure. Some of these may take as
much as five seconds to be reported.
Analyzer flow rates should be stable and
should be controlled similarly on zero,
span and sample. The Analyzer module
should respond to its span gases at its
specification (depending on its filter set-
tings), but bear in mind the exponential
time response and allow ten time con-
stants for real stability.
The main screen will wash out in direct
sunlight, but it should be bright enough to
read in complete darkness or ordinary
room light.
Analyzers should warm up within about
an hour, and should show stability within
one day, other than Trace O
2
s or FIDs
which have special considerations.
Analyzers should show no sign of wet-
ness in their sample tubing. FIDs will
show water condensate in their exhaust.
Analyzers should not be too hot to touch,
except possibly for heated FIDs.
There should be no perceptible stepping
on the trace of a chart recorder from an
I/O module (as normally configured).
The system should remember how it is
configured no matter how it is powered up
or down, and it should always be possible
to enter any module’s menus.