Teledyne OT-3 - Manual (Page 36)

Operation OT-3
Teledyne Analytical Instruments 28
will cause the display to flash NO PASS and the keys will
have no effect.
4. To unlock the keypad, repeat steps 1 and 2. Enter the number 10
when the word PASS CODE blinks on the display.
4.7 Selecting a Fixed Range or Autoranging
The Model OT-3 can operate in fixed high, fixed low, or
autoranging mode. These modes are user-selectable. To change modes:
1. Press and then release the SET HI RANGE and the SET LO
RANGE buttons simultaneously.
2. Within 5 seconds, press either the ∆ or ∇ button until Auto, Lo,
or Hi displays on the LED, as desired.
After about three seconds, the analyzer resumes monitoring in the
selected range mode.
Note: If the concentration exceeds 9999 ppm oxygen, the
analyzer will automatically switch to the Calibration Range,
EVEN THOUGH INSTRUMENT IS IN THE FIXED RANGE
MODE.
4.8 Calibration
Preliminary—If not already done: Power up the Analyzer and allow
the LED reading to stabilize. Set the Alarm setpoints and the full-scale
ranges to the desired values.
Procedure:
Note: This procedure requires a suitable span gas with pressure
regulation.
The O
2
concentration of the span gas should be 80-90% of the
principle range of use— typically 8-9 ppm or 80-90 ppm.
1. Attach the pressure regulated span gas to the to the span port on
the bottom of the analyzer as described in Section 3.4.
2. Move the gas selector valve to the SPAN position.
3. Adjust the pressure on the span gas to produce a 0.4-0.5 SCFH
flow and allow the analyzer to stabilize before setting the span.
4. The analyzer reading should be stable prior to setting the span.