Emerson NGA2000 TO2 instruction manual Pressure, Calibration Gases, Connections

Instruction Manual

748374-F March 2003

Model NGA2000 TO2

with a clean, metallic diaphragm, two-stage	Pressure
regulator. A shutoff valve is recommended.	Constant between 13.8 and 69 hPa - gauge
Calibration Gases	(0.2 and 1.0 psig) sample inlet pressure is
	recommended. If a needle valve is used
The TO2 module does not require routine	upstream of the Analyzer Module to control
zero calibration. The zero is factory set and	flow, the inlet pressure to the needle valve
does not experience routine drift. Over long	should not exceed 345 hPa (5 psig). A
periods of time, the zero may experience	constant sample flow rate between 1.0 to
minor drift. For low ppm range analyzers,	3.0 SCFH (0.5 to 1.5 l/min) is recommended
you may wish to check the zero at one year	for best results. The Analyzer Module must
intervals. Oxygen-free nitrogen is recom-	vent to atmosphere to avoid back pressure
mended for use as zero gas. This gas is	influences on the oxygen reading.
certified to <0.5 ppm oxygen and can be
improved by passing the zero gas through	b. Connections
an oxygen scrubber such as Millipore™
Waferpure or Semigas Nanochem® resin	(See Figure 2-3 on page 2-4 ) Connect inlet
purifiers. A mixture of trace oxygen in a	and outlet lines for sample to appropriately
background of nitrogen is recommended as	labeled fittings on the rear panel. SAMPLE
span gas. For maximum accuracy, the con-	IN and SAMPLE OUT are 1/4-inch ferrule-
centration of trace oxygen in the span gas	type compression fittings. Zero and span
should be as high as possible for the range	gases should be introduced at the SAMPLE
of measurement.	IN fitting at normal sample inlet flow rate.
Sample	Metallic tubing is recommended for the
The sample must be clean and dry before	sample line. The use of plastic, Teflon, or
	other non-metallic tubing can result in am-
entering the Analyzer Module. Sample
	bient oxygen permeation through the tubing
should be filtered for particulates down to
	causing higher than expected reading. Ex-
two microns, and should have a dewpoint at
	haust tubing should be 1/4 inch (6.3 mm) or
least 5 °C (13 °F) below the coldest ex-
	larger, and can be metallic or non-metallic.
pected ambient temperature.

ANALYZER MODULE	BACKPLANE
CONNECTIONS	CONNECTIONS
Network 1	Backplane
Network 2
Power	Controller Board
	Connector
Fuse	Network
Power Indicator Light
	Power

Figure 2-1. Analyzer Module Interconnection with Instrument Platform

2-2 Installation Rosemount Analytical Inc. A Division of Emerson Process Management