Teledyne 3350 - Microprocessor based control room monitor for personnel safety - Manual (Page 31)

Alarm Oxygen Monitor Operation 4
4-3 Teledyne Analytical Instruments
that concentration. To eliminate any error caused by the calibration gas,
always use a certified composition with an oxygen concentration between
80% and 90% of the full scale meter reading of the analyzer.
CAUTION: Calibration in the same atmosphere that is being monitored can
result in serious error. The analysis performed and the alarms, if
any, generated by this instrument when calibrated using the
monitored atmosphere or a span gas of unknown composition,
will be meaningless.
Preliminary—If not already done: Power up the Analyzer and
allow the LED reading to stabilize.
Procedure:
1. Expose the sensor to ambient air or instrument grade air (20.9%
oxygen). Allow time for the analyzer to achieve equilibrium.
Note: If the analyzer goes overrange, the display will go blank and the front
panel ALARM Indicator, beneath the SET Function buttons, will blink.
Hold down the SPAN button until the ALARM Indicator stops blinking.
2. Press the SPAN button once.
3. Immediately (within 5 seconds) press either the
Δ or ∇ button
until the display is stable and reads 20.9%.
Note: When an arrow button is first pressed, the LED begins flashing
slightly more rapidly and no longer tracks the span gas. Instead, it
responds to the UP/DOWN keystrokes.
Note: While the LED is flashing slightly more rapidly, the SPAN routine will
time-out in five seconds (instead of five minutes), if no further key-
strokes are entered.
4. When the span value is set to 20.9% Oxygen, stop pressing the
keys and wait for five seconds.
The unit is now calibrated. (also see section 4 operation)
Note: The alarms will be disabled for about 25 seconds after the SPAN
button is released. Disabling the alarms allows air to be cleared from
the sensor without tripping any alarm set below span (20.9%).
Supplementary Information
If, during the Span Procedure, you pressed the SPAN button by mis-
take, you must wait five minutes for the analyzer to resume analisis or you
can press the UP button and then the DOWN button. (Pressing the UP and
DOWN buttons causes the analyzer to time-out in five seconds instead of
five minutes).