GX-6000 Operator’s Manual
Chapter 2: Description • 17
adjustment options.
Vibrator
A vibrating motor inside the GX-6000 case vibrates for gas alarms, unit malfunctions, and
as an indicator during normal use of the various modes of the GX-6000.
Printed Circuit Boards (PCBs)
The GX-6000 printed circuit boards analyze, record, control, store, and display the
information collected. The circuit boards are located inside the case. They are not user
serviceable.
Pump
A diaphragm pump inside the GX-6000 draws the sample to the sensors. It can draw
sample from as far as 50 feet from the GX-6000. The pump is not user serviceable.
CAUTION:
Sample hose lengths of more than 50 feet are not recommended for the
GX-6000 because of flow rate reduction.
Flow Chamber
The flow chamber is on the back of the GX-6000 and is held in place by four Phillips
screws. The flow chamber seals to the rubber sensor gasket which seals to the sensor faces
inside the GX-6000 and routes flow from the pump to the sensors and to the exhaust port
(on the top of the GX-6000 case).
Sensors
The GX-6000 uses five sensors to monitor combustible gas, oxygen (O
2
), carbon
monoxide (CO), hydrogen sulfide (H
2
S), and isobutylene (IBL) simultaneously. The
sensors are located inside the GX-6000 and are held in their sockets by the flow chamber.
The sensors use different detection principles, as described below.
Combustible Gas Sensor
The % LEL sensor detects combustible gas in the % LEL range. It uses a catalytic element
for detection. 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 GX-6000’s circuitry, converted to a measurement of combustible gas
concentration, and displayed on the LCD.
The standard calibration for the combustible gas sensor is to methane but the sensor will
still detect and respond to a variety of combustible gases.
Oxygen Sensor
The O
2
sensor is a galvanic type of 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-6000’s circuitry, converted to a measurement of gas
concentration, and displayed on the LCD.
