GX-2009 Operator’s Manual
Description • 13
Oxygen (O
2
) Sensor
The O
2
sensor is a galvanic type sensor. A membrane covers the cell and allows gas to diffuse
into the cell at a rate proportional to the partial pressure of oxygen. The oxygen reacts in the
cell and produces a voltage proportional to the concentration of oxygen. The voltage is
measured by the GX-2009’s circuitry, converted to a measurement of gas concentration, and
displayed on the LCD.
CO and H
2
S Sensors
The CO and H
2
S sensors are electrochemical sensors that consist of two precious metal
electrodes in an acid electrolyte. A gas permeable membrane covers the sensor face and
allows gas to diffuse into the electrolyte. The gas reacts in the sensor and produces a current
proportional to the concentration of the target gas. The current is amplified by the GX-2009’s
circuitry, converted to a measurement of gas concentration, and displayed on the LCD.
LCD
The LCD (liquid crystal display) is visible through the GX-2009’s front window. Target gas
concentrations, the time, battery condition, and alarm indications are displayed on the LCD.
When either of the control buttons are pressed, the LCD backlight comes on for 30 seconds.
Control Buttons
Two control buttons are located below the display on either side of the front buzzer opening.
The AIR button is on the left and the POWER MODE button is on the right. The functions
performed by the control buttons are summarized in the following table:
Table 2: GX-2009 Control Buttons
Button
Function
POWER MODE
• Turns the unit on and off
• Turns the LCD back light on
• Scrolls through Display Mode
• Resets the alarm circuit (gas alarms)
• Enters Calibration Mode with the AIR button
• Enters User Setup Mode with the AIR button
• Selects a displayed item
• Saves adjusted parameters
• Selects displayed parameters
AIR
• Turns the LCD back light on.
• Performs a fresh air adjustment
• Enters Calibration Mode with the MODE POWER button.
• Enters User Setup Mode with the MODE POWER button.
• Adjusts or changes displayed parameters
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