Trace Oxygen Analyzer Operation 4
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Teledyne Analytical Instruments
nitrogen and helium will not require SPAN adjustment. However, care must
be taken to keep sample flow rates in the desired levels, as the flowmeter is
calibrated for air and nitrogen streams only.
3. The analyzer can withstand repeated switching of streams between
low oxygen levels of less than 1 ppm and high oxygen levels of 5000 to
10,000 ppm. Again, care must be taken to ensure proper and continuous
flows at all times.
4.5.1 Special Notes on Hydrogen Gas Stream
The standard oxygen cell, Model B-2CXL, though tested in nitrogen
gas streams is expected to perform well in hydrogen streams. Hovewer, for
certain applications such as continuous monitoring of very low levels of
oxygen in hydrogen, the user may request cells that have been specifically
tested in hydrogen streams. Consult Teledyne for further details.
4.6 The Alarms Function
The Model 3000TA-XL is equipped with 2 fully adjustable concentra-
tion alarms and a system failure alarm. Each alarm has a relay with a set of
form “C" contacts rated for 3 amperes resistive load at 250 V ac. See Figure
3-5 in Chapter 3, Installation and/or the Interconnection Diagram included at
the back of this manual for relay terminal connections.
The system failure alarm has a fixed configuration as described in
chapter 3 Installation.
The concentration alarms can be configured from the front panel as
either high or low alarms by the operator. The alarm modes can be set as
latching or non-latching, and either failsafe or non-failsafe, or, they can be
defeated altogether. The setpoints for the alarms are also established using
this function.
Decide how your alarms should be configured. The choice will depend
upon your process. Consider the following four points:
1. Which if any of the alarms are to be high alarms and which if any
are to be low alarms?
Setting an alarm as HIGH triggers the alarm when the oxygen
concentration rises above the setpoint. Setting an alarm as LOW
triggers the alarm when the oxygen concentration falls below the
setpoint.
Decide whether you want the alarms to be set as: