RKI Instruments GX-2001 Canadian Version - Manual (Page 9)

Model GX-2001 Operator’s Manual Description • 9
Beneath the control buttons is the buzzer/vibrator, which is located inside
the unit.
On the right side of the Model GX-2001 are the diffusion ports for the gas
sensors located inside the case. These sensors are, from top to bottom
(and are marked on the case), O
2
, HC (combustible gases), CO, and H
2
S.
On the left side of the case are two brass recharging contacts, which are
used when the unit is placed in the battery charger, and on top of the case
are two alarm lights. There is also an IR (infrared) communications port on
the left side which is used when downloading data to a computer using the
datalogging station. On the back of the unit is a rugged metal belt clip
enabling hands-free gas monitoring.The belt clip may be oriented as shown
in Figure 1 or rotated 180° depending on how the instrument is used.
Sensor Retainer/Sensor Cover Retainer
The sensor retainer holds the gas sensors in place and snaps onto the
right side of the case. It has 4 diffusion ports, one for each sensor, and has
recessed areas in it for the charcoal filter, the H
2
S removal filters, and the
sensor cover. The sensor cover retainer snaps onto the sensor retainer.
Two screws secure the sensor retainer and the sensor cover retainer to the
case.
Sensors
The Model GX-2001 uses four sensors to monitor HC (combustible gases),
O
2
, CO, and H
2
S simultaneously. The sensors are protected by filters that
allow atmosphere to diffuse inward. The sensors use different detection
principles, as described below.
Combustible Gas Sensor
The LEL sensor detects combustible gas and vapors in the atmosphere
with a catalytic element. The reaction of gas with oxygen on the catalyst
causes a change in the resistance of the element which affects the current
flowing through it. The current is amplified by the Model GX-2001’s
circuitry, converted to a measurement of combustible gas concentration,
and displayed on the LCD.
CAUTION: Do not expose the combustible sensor to high concentrations
of combustible gas such as that from a butane lighter.
Exposure to high concentrations of combustible gas may
adversely affect the performance of the sensor.