Calibration and Maintenance
25
The calibration procedure can be aborted at any time by pressing the
CO
,
CO
2
,
TEMP,
or
HUMIDITY
key.
If an error occurs during the
CO
calibration procedure, the Q-T
RAK
will
display the message
“ERR.”
Press the
CO
,
CO
2
,
TEMP,
or
HUMIDITY
key
to abort the calibration. Switching the zero gas with the span gas is an
example of a condition that will cause the
“ERR”
message to come on.
Figure 4–2: CO Calibration
1. Locate the calibration adapter and slide it over the sensing probe. Make
sure that the adapter completely covers the CO diffusion holes at the tip
of the probe.
2. Install the regulator onto the zero calibration gas (must contain 0
2
, e.g.,
zero air) cylinder and connect tubing from the cylinder to the inlet of the
calibration adapter and turn the gas on (0.3 L/min). Make sure the
cylinder is not empty.
3. To put the Q-T
RAK
into CO calibration mode, first put the instrument
into Survey mode, and then press and hold the
CO
key. The display
begins to count down from five to zero. When the count reaches zero,
release the
CO
key immediately. The words
“CALIBRATE ZERO”
should appear on the display. If not, try again.
Note
: DIP switch 7 must be set to the “User Calibration” (ON) position or
the Q-T
RAK
will not go into CO calibration mode. Please refer to
Appendix B: “Internal DIP Switch Settings.”
4. Press
the
SAMPLE
key to take a zero measurement. The Q-T
RAK
will
display a 90-second count-down. When the count-down is completed,
the display shows the word
“CALIBRATE 1”
and the arrow symbols
(
!"
) will be blinking. Turn off the regulator and disconnect the zero
calibration gas.
