44 Getting Started 083730300A DCN8101
2.3.2.4 PNEUMATIC CONNECTIONS: AMBIENT ZERO/PRESSURIZED SPAN OPTION
This option requires that both zero air and span gas be supplied from external sources.
• Span gas will be supplied from a pressurized bottle of calibrated CO gas.
• A critical flow control orifice, internal to the instrument ensures that the proper
flow rate is maintained.
• An internal vent line ensures that the gas pressure of the span gas is reduced to
ambient atmospheric pressure.
• A SHUTOFF valve preserves the span gas source when it is not in use.
• Zero gas is supplied by either an external scrubber or a zero air generator such as the
Teledyne API’s T701.
Source of
SAMPLE GAS
Removed during
calibration
VENT
MODEL 701
Zero Gas
Generator
Calibrated
CO Gas
at span gas
concentration
(Adjust to 30
psig)
VENT here if input
is pressurized
PRESSURE/SPAN
AIR/IZS
SAMPLE
EXHAUST
VENT/SPAN
VENT
Instrument
Chassi s
Exhaust must be
vented outside of
shelter or immediate
area surrounding the
instrument.
Figure 2-18. T300/T300M Pneumatic Connections – Option 50B: Ambient Zero/Pressurized Span
SAMPLE GAS SOURCE
Attach a sample inlet line to the SAMPLE inlet port. The sample input line should not
be more than 2 meters long.
• Maximum pressure of any gas at the sample inlet should not exceed 1.5 in-hg above
ambient pressure and ideally should equal ambient atmospheric pressure.
• In applications where the sample gas is received from a pressurized manifold, a vent must
be placed on the sample gas before it enters the analyzer.
CALIBRATION GAS SOURCES
SPAN GAS
• Attach a gas line from the pressurized source of calibration gas (e.g. a bottle of NIST-SRM
gas) to the SPAN inlet at 30 psig.
ZERO AIR
• Zero air is supplied via a zero air generator such as a Teledyne API’s T701.
• An adjustable valve is installed in the zero air supply line to regulate the gas flow.
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