Crowcon Tetra MO7237, User Manual, Page: 12 / 36

Operation Tetra
II. Operation
2.1 Switch-on sequence
1. Ensure the unit is in clean air.
2.
Switch on
Press and hold the operator button until the red LED flashes.
The instrument begins with testing all the LCD segments on the
operator display screen, the red and blue alarm LEDs, sounder and
internal vibrator alert for about 5 seconds. The sounder may be
silenced by pressing the button. The unit enters a warm up mode and
displays a sequence of screens, see page 3 for more details. At the end
of warm up, the auto zero menu will be displayed.
3. Auto zero menu
Press the operator button with a single click to confirm auto zero.
If the operator button is not pressed within 10 seconds, Tetra will
proceed directly to Run mode without performing a zero. Flammable
and toxic sensors will be set to read zero and the oxygen sensor to
read 20.9%.
NB. If auto zero fails, a warning message will be displayed
and an ‘X’ will appear against the sensor that has failed.
Switch off
To switch off the unit, press and hold the operator button for 5
seconds. A shut-down message ‘OFF IN’ will appear, continue to hold
button until the unit counts down to shut off.
Battery check
Use this time to
check there is sufficient
charge in the battery pack
!
The auto zero function can be disabled or set
to run automatically, without user confirmation:
autozero menu will not appear. See section VIII
PC Interface and software.
NB. During the warm up sequence, the date for next calibration will be
displayed. If the date has expired or has passed, the Tetra unit will display a
warning message that calibration is due. The instrument can still function, but
it is strongly recommended the unit is sent for calibration as soon as possible.
Tetra can be set, using the Portables PC software, for the instrument to
shut down automatically, if the calibration date is passed, to prevent further
operation of the instrument.