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Instruction Manual
760007-A
July 2003
Rosemount Analytical Inc. A Division of Emerson Process Management Installation 2-3
Model NGA2000 PMD
Range = 0% to 5% oxygen
Barometric pressure change after
calibration = 1%
Analyzer Module measurement = 5%
oxygen
Measurement error = 0.01 x 5% oxy-
gen
Fullscale span = 5% oxygen
0.05% oxygen error = 1% of fullscale
The error is more significant for sup-
pressed range 99% to 100%.
An optional barometric pressure
compensation board is available to
automatically perform this correction.
A general rule regarding calibration gas
pressure is that it should be the same as
the expected sample gas pressure during
routine operation.
The above requirement increases the dif-
ficulty of operation at negative gauge
pressure. A suction pump can be con-
nected to the outlet port for drawing sam-
ple through the Analyzer Module. Such
operation necessitates special precau-
tions to ensure accurate readout, includ-
ing the following:
The need for equilibrium between sample
and gas calibration pressures.
Any leakage in the sample handling sys-
tem will decrease readout accuracy.
Flow Rate
Recommended sample flow rate is 800 to
1400 ml/min., ±40 ml/min. Optimum flow
rate is 1100 ml/min.
If flow is held to within tolerance and op-
erating pressure remains constant, zero
and span drift will meet specified limits.
b. Connections
(See Figure 2-3 on page 2-4) Connect
inlet and outlet lines for sample gas to
appropriately labeled fittings on the rear
panel. Both connections are 1/4 inch fer-
rule-type compression fittings.
Zero and span gases use the same inlet
and outlet as the sample. Figure 2-4 on
page 2-5 shows a typical external sample
handling manifold for gas selection. Par-
ticulates must be filtered down to two mi-
crons, gases generally require
pressurization, and flow measurement
metering MUST be present.
c. Leak Test
The Analyzer Module is thoroughly tested
at the factory for gas leakage. The user is
responsible for testing for leakage only at
the inlet and outlet fittings on the rear
panel. The user is also responsible for in-
ternal leak testing periodically and if any
internal pneumatic components are ad-
justed or replaced (with a test procedure
selected by the user).