RKI Instruments GX-2009 Manual - Manual (Page 13)

GX-2009 Operator’s Manual Description • 8
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