4
4 OPERATION
To operate the Dioxor II, you simply . . .
• Set its POWER switch to ON,
• Wait for the instrument to warm up (approx. 1 minute),
• Zero the display (if necessary),
• Take a gas sample.
Detailed operating procedures are presented below:
4.1 Power ON/OFF
Turn on the instrument by sliding its POWER
switch to ON. Observe that when power is first
applied, all numerical LCD segments are tested for
5-15 seconds; after which, the LCD shows the detected SO
2
level. (A
minus sign may appear during power up as the sensor stabilizes.) Turn
off the instrument by sliding the POWER switch to OFF.
Important! When storing the instrument for extended periods of time,
remove the batteries and ensure that the POWER switch is OFF. The
OFF position places a short across the SO
2
sensor, thus keeping the
sensor from being destabilized while not in use.
4.2 Zeroing the Instrument
After being turned on and warmed up for at least 1 minute, the
instrument should indicate 000 ±5 ppm in fresh air. If the instrument
needs to be zeroed, proceed as follows:
1. Ensure that the instrument is sampling air that is free of sulfur
dioxide.
NOTE: An indication that the instrument was not zeroed in fresh
air is when a large negative
SO
2
display appears when the
instrument is moved into another area.
2. Using a 1/8" flat-blade screwdriver, turn the
ADJUST potentiometer until the LCD shows 0
ppm. The display shows negative numbers for
zeroing purposes. An instrument can be considered zeroed with a
display bounce of up to ±3 ppm.
